TY  - CONF
AU  - Ljubojević, Pavle
AU  - Ćoćić, Aleksandar
AU  - Lazović, Tatjana
PY  - 2023
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/7167
AB  - This paper presents the mathematical model for determining the quantity of lubricant in contact between balls and raceways of a deep groove ball bearing. In the deep groove ball bearing, balls participate in transferring the load from one ring to another, as they pass through the contact zone [1]. In doing so, the balls are in mutual elastohydrodynamic lubrication (EHL) contact with the raceways [2]. In the EHL contact between the balls and the raceway, there is a certain amount of lubricant between contacting surfaces. The volume of lubricant in contact can be determined as the product of the contact zone's area multiplied by the thickness of the lubricant film between them. The relationship between the lubricant volume VLq (q = 1 for ball-outer ring contact, q = 2 for ball-inner ring contact) within the contact zone and the relative radial clearance e/δ0 (e – radial clearance; δ0 – contact deformation between ball and raceway) as well as the relative operational load FR/C (FR – operational load; C – bearing dynamic load rating) of the deep groove ball bearing 6206 is shown in Figure below. Based on the known quantity of lubricant volume VL within both contact zones, it becomes possible to estimate the concentration of contaminating particles that are entrapped in contact between ball raceways. This estimation can be related to the overall known concentration of abrasive particles within the bearing lubricant. Through this approach, it becomes feasible to assess and predict the level of abrasive wear occurring within bearing components during operation.
PB  - Trans Tech Publications Ltd, Switzerland
C3  - Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering
T1  - Impact of Ball Bearing Geometry and Operational Load on the Volume of the Lubricant in the Bearing's Loaded Zone
EP  - 61
SP  - 60
UR  - https://hdl.handle.net/21.15107/rcub_machinery_7167
ER  - 

@conference{
author = "Ljubojević, Pavle and Ćoćić, Aleksandar and Lazović, Tatjana",
year = "2023",
abstract = "This paper presents the mathematical model for determining the quantity of lubricant in contact between balls and raceways of a deep groove ball bearing. In the deep groove ball bearing, balls participate in transferring the load from one ring to another, as they pass through the contact zone [1]. In doing so, the balls are in mutual elastohydrodynamic lubrication (EHL) contact with the raceways [2]. In the EHL contact between the balls and the raceway, there is a certain amount of lubricant between contacting surfaces. The volume of lubricant in contact can be determined as the product of the contact zone's area multiplied by the thickness of the lubricant film between them. The relationship between the lubricant volume VLq (q = 1 for ball-outer ring contact, q = 2 for ball-inner ring contact) within the contact zone and the relative radial clearance e/δ0 (e – radial clearance; δ0 – contact deformation between ball and raceway) as well as the relative operational load FR/C (FR – operational load; C – bearing dynamic load rating) of the deep groove ball bearing 6206 is shown in Figure below. Based on the known quantity of lubricant volume VL within both contact zones, it becomes possible to estimate the concentration of contaminating particles that are entrapped in contact between ball raceways. This estimation can be related to the overall known concentration of abrasive particles within the bearing lubricant. Through this approach, it becomes feasible to assess and predict the level of abrasive wear occurring within bearing components during operation.",
publisher = "Trans Tech Publications Ltd, Switzerland",
journal = "Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering",
title = "Impact of Ball Bearing Geometry and Operational Load on the Volume of the Lubricant in the Bearing's Loaded Zone",
pages = "61-60",
url = "https://hdl.handle.net/21.15107/rcub_machinery_7167"
}

Ljubojević, P., Ćoćić, A.,& Lazović, T.. (2023). Impact of Ball Bearing Geometry and Operational Load on the Volume of the Lubricant in the Bearing's Loaded Zone. in Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering
Trans Tech Publications Ltd, Switzerland., 60-61.
https://hdl.handle.net/21.15107/rcub_machinery_7167

Ljubojević P, Ćoćić A, Lazović T. Impact of Ball Bearing Geometry and Operational Load on the Volume of the Lubricant in the Bearing's Loaded Zone. in Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering. 2023;:60-61.
https://hdl.handle.net/21.15107/rcub_machinery_7167 .

Ljubojević, Pavle, Ćoćić, Aleksandar, Lazović, Tatjana, "Impact of Ball Bearing Geometry and Operational Load on the Volume of the Lubricant in the Bearing's Loaded Zone" in Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering (2023):60-61,
https://hdl.handle.net/21.15107/rcub_machinery_7167 .

TY  - JOUR
AU  - Raković, Milan
AU  - Radenković, Darko
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3693
AB  - In this work, numerical simulations of upward turbulent bubbly flows in vertical pipes are conducted in the Euler-Euler framework with a low-Reynolds-number (LRN) model for liquid. It is found that the existing correlation for the drag coefficient of a single bubble in a shear flow, which has been successfully used along with the high-Reynolds-number (HRN) models, cannot be used with the LRN model. The reason is that drag forces of bubbles calculated using such correlation are enormous in near-wall cells (order of 10(12) N/m(3)), which causes a divergence of numerical simulations with LRN. Therefore, a modified correlation for the drag coefficient of a single bubble in shear flow, that can be used successfully with the LRN model, has been proposed. The results of numerical simulations, performed with a new correlation for the drag coefficient, are analysed and compared to selected experimental measurements for different pipe diameters and different flow conditions of gas and liquid. It is shown that the largest effect of the application of the new correlation for the drag coefficient of a single bubble in shear flow in numerical simulations can be achieved on the reduction of the relative velocity between gas and liquid. The degree of this reduction depends on the pipe diameter and liquid volumetric flux.
PB  - Sage Publications Ltd, London
T2  - Advances in Mechanical Engineering
T1  - Euler-Euler numerical simulations of upward turbulent bubbly flows in vertical pipes with low-Reynolds-number model
IS  - 4
VL  - 14
DO  - 10.1177/16878132221094909
ER  - 

@article{
author = "Raković, Milan and Radenković, Darko and Ćoćić, Aleksandar and Lečić, Milan",
year = "2022",
abstract = "In this work, numerical simulations of upward turbulent bubbly flows in vertical pipes are conducted in the Euler-Euler framework with a low-Reynolds-number (LRN) model for liquid. It is found that the existing correlation for the drag coefficient of a single bubble in a shear flow, which has been successfully used along with the high-Reynolds-number (HRN) models, cannot be used with the LRN model. The reason is that drag forces of bubbles calculated using such correlation are enormous in near-wall cells (order of 10(12) N/m(3)), which causes a divergence of numerical simulations with LRN. Therefore, a modified correlation for the drag coefficient of a single bubble in shear flow, that can be used successfully with the LRN model, has been proposed. The results of numerical simulations, performed with a new correlation for the drag coefficient, are analysed and compared to selected experimental measurements for different pipe diameters and different flow conditions of gas and liquid. It is shown that the largest effect of the application of the new correlation for the drag coefficient of a single bubble in shear flow in numerical simulations can be achieved on the reduction of the relative velocity between gas and liquid. The degree of this reduction depends on the pipe diameter and liquid volumetric flux.",
publisher = "Sage Publications Ltd, London",
journal = "Advances in Mechanical Engineering",
title = "Euler-Euler numerical simulations of upward turbulent bubbly flows in vertical pipes with low-Reynolds-number model",
number = "4",
volume = "14",
doi = "10.1177/16878132221094909"
}

Raković, M., Radenković, D., Ćoćić, A.,& Lečić, M.. (2022). Euler-Euler numerical simulations of upward turbulent bubbly flows in vertical pipes with low-Reynolds-number model. in Advances in Mechanical Engineering
Sage Publications Ltd, London., 14(4).
https://doi.org/10.1177/16878132221094909

Raković M, Radenković D, Ćoćić A, Lečić M. Euler-Euler numerical simulations of upward turbulent bubbly flows in vertical pipes with low-Reynolds-number model. in Advances in Mechanical Engineering. 2022;14(4).
doi:10.1177/16878132221094909 .

Raković, Milan, Radenković, Darko, Ćoćić, Aleksandar, Lečić, Milan, "Euler-Euler numerical simulations of upward turbulent bubbly flows in vertical pipes with low-Reynolds-number model" in Advances in Mechanical Engineering, 14, no. 4 (2022),
https://doi.org/10.1177/16878132221094909 . .

TY  - CONF
AU  - Raković, Milan
AU  - Lečić, Lazar
AU  - Ćoćić, Aleksandar
AU  - Janković, Novica
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6276
C3  - Full Paper Proceedings International Conference IEEP2022
T1  - Experimental Аnd Numerical Investigation of Ball Valve Characteristics
SP  - 252
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6276
ER  - 

@conference{
author = "Raković, Milan and Lečić, Lazar and Ćoćić, Aleksandar and Janković, Novica",
year = "2022",
journal = "Full Paper Proceedings International Conference IEEP2022",
title = "Experimental Аnd Numerical Investigation of Ball Valve Characteristics",
pages = "252",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6276"
}

Raković, M., Lečić, L., Ćoćić, A.,& Janković, N.. (2022). Experimental Аnd Numerical Investigation of Ball Valve Characteristics. in Full Paper Proceedings International Conference IEEP2022, 252.
https://hdl.handle.net/21.15107/rcub_machinery_6276

Raković M, Lečić L, Ćoćić A, Janković N. Experimental Аnd Numerical Investigation of Ball Valve Characteristics. in Full Paper Proceedings International Conference IEEP2022. 2022;:252.
https://hdl.handle.net/21.15107/rcub_machinery_6276 .

Raković, Milan, Lečić, Lazar, Ćoćić, Aleksandar, Janković, Novica, "Experimental Аnd Numerical Investigation of Ball Valve Characteristics" in Full Paper Proceedings International Conference IEEP2022 (2022):252,
https://hdl.handle.net/21.15107/rcub_machinery_6276 .

TY  - CONF
AU  - Raković, Milan
AU  - Radenković, Darko
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6219
AB  - Numerical simulations of upward turbulent bubbly flows in vertical pipes are carried
out in the Euler-Euler framework with a low-Reynolds-number (LRN) model for liquid for
various flow conditions. It is found that the correlation for the drag coefficient of a single
bubble in a shear flow, which has been successfully used in numerical simulations with
the high-Reynolds-number (HRN) models, cannot be used with the LRN model. The
reason is an excessive value of drag coefficient of a single bubble in the near-wall cells.
Therefore, a new correlation for the drag coefficient of a single bubble in shear flow has
been proposed. The results of numerical simulations are analysed and compared to
selected experiment results. It is shown that the largest effect of the application of the
new correlation for the drag coefficient of a single bubble in shear flow can be achieved
on the reduction of the relative velocity between gas and liquid. Overall, the results of
numerical simulations agree well with the experimental results.
C3  - ICAS 2022 Book of abstracts
T1  - Influence of the drag coefficient of a single bubble in vertical upward turbulent bubbly flows
SP  - 85
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6219
ER  - 

@conference{
author = "Raković, Milan and Radenković, Darko and Ćoćić, Aleksandar and Lečić, Milan",
year = "2022",
abstract = "Numerical simulations of upward turbulent bubbly flows in vertical pipes are carried
out in the Euler-Euler framework with a low-Reynolds-number (LRN) model for liquid for
various flow conditions. It is found that the correlation for the drag coefficient of a single
bubble in a shear flow, which has been successfully used in numerical simulations with
the high-Reynolds-number (HRN) models, cannot be used with the LRN model. The
reason is an excessive value of drag coefficient of a single bubble in the near-wall cells.
Therefore, a new correlation for the drag coefficient of a single bubble in shear flow has
been proposed. The results of numerical simulations are analysed and compared to
selected experiment results. It is shown that the largest effect of the application of the
new correlation for the drag coefficient of a single bubble in shear flow can be achieved
on the reduction of the relative velocity between gas and liquid. Overall, the results of
numerical simulations agree well with the experimental results.",
journal = "ICAS 2022 Book of abstracts",
title = "Influence of the drag coefficient of a single bubble in vertical upward turbulent bubbly flows",
pages = "85",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6219"
}

Raković, M., Radenković, D., Ćoćić, A.,& Lečić, M.. (2022). Influence of the drag coefficient of a single bubble in vertical upward turbulent bubbly flows. in ICAS 2022 Book of abstracts, 85.
https://hdl.handle.net/21.15107/rcub_machinery_6219

Raković M, Radenković D, Ćoćić A, Lečić M. Influence of the drag coefficient of a single bubble in vertical upward turbulent bubbly flows. in ICAS 2022 Book of abstracts. 2022;:85.
https://hdl.handle.net/21.15107/rcub_machinery_6219 .

Raković, Milan, Radenković, Darko, Ćoćić, Aleksandar, Lečić, Milan, "Influence of the drag coefficient of a single bubble in vertical upward turbulent bubbly flows" in ICAS 2022 Book of abstracts (2022):85,
https://hdl.handle.net/21.15107/rcub_machinery_6219 .

TY  - CONF
AU  - Ćoćić, Aleksandar
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5527
AB  - Solar energy is renewable, clean and practically non-depletable energy source - it is estimated that we will have steady, unlimited supply of sunlight for another 5 billion years. Efficient utilization of solar energy and development of solar systems in that purpose are the research topics of many scientists  and engineers worldwide. Solar updraft tower (SUT) technology is attracting interest in many regions worldwide, being a compelling prospect for producing  clean and renewable energy.  Very import operational parameters of SUT systems are mass flow rate and pressure difference inside the tower. Based on the  assumption of one-dimensional (1D) flow, a comprehensive mathematical model for buoyancy driven air flow inside the SUT power plant is developed. It consists of system of nonlinear differential equations which describes the flow inside collector and the tower, and algebraic equations which describes the flow in collector to tower transition section and turbines. Validity of the model is confirmed by numerical solution of the equations for the case of Manzaneres SUT, where good agreement is found between obtained solution and available experimental data. Dimensionless form of model equations are further developed which enables the performance analysis of SUT systems. It is found that only large-scale systems are feasible, and that increase in tower height increase the mass flow rate only to some extent. Additionally, CFD computations based on Boussinesq model for
buoyancy-driven flow and  using Reynold-Averaged Navier-Stokes (RANS) equations are performed where good agreement is found with derived 1D model.
C3  - Proceedings International Conference IEEP2022, VIII Regional Conference: INDUSTRIAL ENERGY AND ENVIRONMENTAL PROTECTION IN THE COUNTRIES OF SOUTHEAST EUROPE
T1  - Solar updraft tower technology as clean and renewable energy source
EP  - 438
SP  - 424
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5527
ER  - 

@conference{
author = "Ćoćić, Aleksandar",
year = "2022",
abstract = "Solar energy is renewable, clean and practically non-depletable energy source - it is estimated that we will have steady, unlimited supply of sunlight for another 5 billion years. Efficient utilization of solar energy and development of solar systems in that purpose are the research topics of many scientists  and engineers worldwide. Solar updraft tower (SUT) technology is attracting interest in many regions worldwide, being a compelling prospect for producing  clean and renewable energy.  Very import operational parameters of SUT systems are mass flow rate and pressure difference inside the tower. Based on the  assumption of one-dimensional (1D) flow, a comprehensive mathematical model for buoyancy driven air flow inside the SUT power plant is developed. It consists of system of nonlinear differential equations which describes the flow inside collector and the tower, and algebraic equations which describes the flow in collector to tower transition section and turbines. Validity of the model is confirmed by numerical solution of the equations for the case of Manzaneres SUT, where good agreement is found between obtained solution and available experimental data. Dimensionless form of model equations are further developed which enables the performance analysis of SUT systems. It is found that only large-scale systems are feasible, and that increase in tower height increase the mass flow rate only to some extent. Additionally, CFD computations based on Boussinesq model for
buoyancy-driven flow and  using Reynold-Averaged Navier-Stokes (RANS) equations are performed where good agreement is found with derived 1D model.",
journal = "Proceedings International Conference IEEP2022, VIII Regional Conference: INDUSTRIAL ENERGY AND ENVIRONMENTAL PROTECTION IN THE COUNTRIES OF SOUTHEAST EUROPE",
title = "Solar updraft tower technology as clean and renewable energy source",
pages = "438-424",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5527"
}

Ćoćić, A.. (2022). Solar updraft tower technology as clean and renewable energy source. in Proceedings International Conference IEEP2022, VIII Regional Conference: INDUSTRIAL ENERGY AND ENVIRONMENTAL PROTECTION IN THE COUNTRIES OF SOUTHEAST EUROPE, 424-438.
https://hdl.handle.net/21.15107/rcub_machinery_5527

Ćoćić A. Solar updraft tower technology as clean and renewable energy source. in Proceedings International Conference IEEP2022, VIII Regional Conference: INDUSTRIAL ENERGY AND ENVIRONMENTAL PROTECTION IN THE COUNTRIES OF SOUTHEAST EUROPE. 2022;:424-438.
https://hdl.handle.net/21.15107/rcub_machinery_5527 .

Ćoćić, Aleksandar, "Solar updraft tower technology as clean and renewable energy source" in Proceedings International Conference IEEP2022, VIII Regional Conference: INDUSTRIAL ENERGY AND ENVIRONMENTAL PROTECTION IN THE COUNTRIES OF SOUTHEAST EUROPE (2022):424-438,
https://hdl.handle.net/21.15107/rcub_machinery_5527 .

TY  - CONF
AU  - Milivojević, Marija
AU  - Ćoćić, Aleksandar
AU  - Tomić, Matej
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5526
AB  - Air-to-liquid heat exchangers which are used in the automotive industry are of fin and tube type. In conjunction with the heat exchanger, axial fans are used, for two main reasons: to compensate the pressure drop of air and to enhance the cooling efficiency. In design process of heat exchanger, it is necessary to choose the appropriate axial fan which will meet the demands. One of the main data set in that sense is the relationship between the air volumetric flow rate and pressure drop in the heat exchanger. In this paper, air flow through the fin and tube type heat exchanger is analyzed using steady-state numerical simulations. Since it is practically impossible to generate the numerical grid for  the real, physical fins, they are modeled using the porous media approach, with Darcy-Forchheimer model, applied in defined cell zone which corresponds to fins. By this, additional sink/source term is added in momentum equation. From series of numerical computations, where the inlet flow rate is varied, the relationship between pressure drop in porous zone and flow rate is established. Flow of the air is treated as incompressible and isothermal. OpenFOAM, free and open-source software for computational fluid dynamics (CFD) is used for aforementioned computations. The control volume is modeled to match the experimental airflow test rig set up, while for the boundary conditions velocity inlet and pressure outlet are used. Symmetry boundary condition is applied at the longitudinal plane of the model, in order to reduce the mesh count. Values of coefficients in Darcy-Forchheimer model are estimated from the geometrical characteristics of the heat exchanger and available experimental data. It is concluded that porous media approach implemented in OpenFOAM software can be used as toolkit in prediction of pressure of drop from the air side in automotive heat exchanger.
C3  - First International Conference on Mathematical Modeling in Mechanics and Engineering, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia, 8-10 September 2022
T1  - Analysis of Pressure Drop From The Air Side in Automotive Heat Exchanger Using Porous Media Approach
SP  - 86
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5526
ER  - 

@conference{
author = "Milivojević, Marija and Ćoćić, Aleksandar and Tomić, Matej",
year = "2022",
abstract = "Air-to-liquid heat exchangers which are used in the automotive industry are of fin and tube type. In conjunction with the heat exchanger, axial fans are used, for two main reasons: to compensate the pressure drop of air and to enhance the cooling efficiency. In design process of heat exchanger, it is necessary to choose the appropriate axial fan which will meet the demands. One of the main data set in that sense is the relationship between the air volumetric flow rate and pressure drop in the heat exchanger. In this paper, air flow through the fin and tube type heat exchanger is analyzed using steady-state numerical simulations. Since it is practically impossible to generate the numerical grid for  the real, physical fins, they are modeled using the porous media approach, with Darcy-Forchheimer model, applied in defined cell zone which corresponds to fins. By this, additional sink/source term is added in momentum equation. From series of numerical computations, where the inlet flow rate is varied, the relationship between pressure drop in porous zone and flow rate is established. Flow of the air is treated as incompressible and isothermal. OpenFOAM, free and open-source software for computational fluid dynamics (CFD) is used for aforementioned computations. The control volume is modeled to match the experimental airflow test rig set up, while for the boundary conditions velocity inlet and pressure outlet are used. Symmetry boundary condition is applied at the longitudinal plane of the model, in order to reduce the mesh count. Values of coefficients in Darcy-Forchheimer model are estimated from the geometrical characteristics of the heat exchanger and available experimental data. It is concluded that porous media approach implemented in OpenFOAM software can be used as toolkit in prediction of pressure of drop from the air side in automotive heat exchanger.",
journal = "First International Conference on Mathematical Modeling in Mechanics and Engineering, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia, 8-10 September 2022",
title = "Analysis of Pressure Drop From The Air Side in Automotive Heat Exchanger Using Porous Media Approach",
pages = "86",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5526"
}

Milivojević, M., Ćoćić, A.,& Tomić, M.. (2022). Analysis of Pressure Drop From The Air Side in Automotive Heat Exchanger Using Porous Media Approach. in First International Conference on Mathematical Modeling in Mechanics and Engineering, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia, 8-10 September 2022, 86.
https://hdl.handle.net/21.15107/rcub_machinery_5526

Milivojević M, Ćoćić A, Tomić M. Analysis of Pressure Drop From The Air Side in Automotive Heat Exchanger Using Porous Media Approach. in First International Conference on Mathematical Modeling in Mechanics and Engineering, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia, 8-10 September 2022. 2022;:86.
https://hdl.handle.net/21.15107/rcub_machinery_5526 .

Milivojević, Marija, Ćoćić, Aleksandar, Tomić, Matej, "Analysis of Pressure Drop From The Air Side in Automotive Heat Exchanger Using Porous Media Approach" in First International Conference on Mathematical Modeling in Mechanics and Engineering, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia, 8-10 September 2022 (2022):86,
https://hdl.handle.net/21.15107/rcub_machinery_5526 .

TY  - CONF
AU  - Ćoćić, Aleksandar
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5525
AB  - Finite volume method is predominantly used in computational fluid dynamics (CFD), and it is very rarely used in computational solid mechanics. But essentially, it is just one approach for numerical solution of PDEs (FVM discretises strong conservative form of momentum equation, while FEM uses weak form). OpenFOAM, free and open-source CFD software is used as the tool for implementation of numerical solutions  of equations (a), (b) and (c). General FVM solver, based on the (a) is implemented using OpenFOAM libraries, together with appropriate Neumann BC. The solver is then tested on many examples, starting from the problems with known analytical solution (excellent agreement is found). Additional post-processing is implemented within the solver, where after determination of shear stress (calculated from the gradient of warping function field), Prandtl stress function is calculated as the stream function of stress vector field. It is shown that boundary-fitted grid which is characteristic for FVM is very suited for considered computations.  Finally, analogy between elastic torsion and some classical fluid mechanics problems governed with the same type of the equations is analyzed.
C3  - First International Conference on Mathematical Modeling in Mechanics and Engineering
T1  - Numerical Computations of Elastic Torsion Using the Finite-Volume Method
SP  - 120
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5525
ER  - 

@conference{
author = "Ćoćić, Aleksandar",
year = "2022",
abstract = "Finite volume method is predominantly used in computational fluid dynamics (CFD), and it is very rarely used in computational solid mechanics. But essentially, it is just one approach for numerical solution of PDEs (FVM discretises strong conservative form of momentum equation, while FEM uses weak form). OpenFOAM, free and open-source CFD software is used as the tool for implementation of numerical solutions  of equations (a), (b) and (c). General FVM solver, based on the (a) is implemented using OpenFOAM libraries, together with appropriate Neumann BC. The solver is then tested on many examples, starting from the problems with known analytical solution (excellent agreement is found). Additional post-processing is implemented within the solver, where after determination of shear stress (calculated from the gradient of warping function field), Prandtl stress function is calculated as the stream function of stress vector field. It is shown that boundary-fitted grid which is characteristic for FVM is very suited for considered computations.  Finally, analogy between elastic torsion and some classical fluid mechanics problems governed with the same type of the equations is analyzed.",
journal = "First International Conference on Mathematical Modeling in Mechanics and Engineering",
title = "Numerical Computations of Elastic Torsion Using the Finite-Volume Method",
pages = "120",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5525"
}

Ćoćić, A.. (2022). Numerical Computations of Elastic Torsion Using the Finite-Volume Method. in First International Conference on Mathematical Modeling in Mechanics and Engineering, 120.
https://hdl.handle.net/21.15107/rcub_machinery_5525

Ćoćić A. Numerical Computations of Elastic Torsion Using the Finite-Volume Method. in First International Conference on Mathematical Modeling in Mechanics and Engineering. 2022;:120.
https://hdl.handle.net/21.15107/rcub_machinery_5525 .

Ćoćić, Aleksandar, "Numerical Computations of Elastic Torsion Using the Finite-Volume Method" in First International Conference on Mathematical Modeling in Mechanics and Engineering (2022):120,
https://hdl.handle.net/21.15107/rcub_machinery_5525 .

TY  - JOUR
AU  - Burazer, Jela M.
AU  - Novković, Đorđe 
AU  - Ćoćić, Aleksandar
AU  - Bukurov, M.
AU  - Lečić, Milan
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3713
AB  - Vortex tube is a device without moving parts with ability to separate pressurized gas into two streams: cold and hot. This is a consequence of the Eckert-Wiese effect, which is responsible for spontaneous redistribution of total energy within the flow domain. In order for vortex tubes to work properly, there are some constraints which have to be fulfilled. The most important constraint in that sense is the L/D ratio. One part of this paper is dedicated to the research of the influence of L/D ratio on the energy separation in a vortex tube, i.e. to the values of total temperatures on cold and hot outlets of the device. On the other hand, experimental research of the inner flow is quite challenging since vortex tube is a device of small dimensions. Hence, we are relaying on numerical computations. One of important quantities that has to be prescribed in these computations is the turbulent Prandtl number Pr-T. Because of that, the other part of this paper is dedicated to research of the influence of Pr-T on the results of numerical computations. The research is conducted using open-source software OpenFOAM. Turbulence is modelled using two-equation and RST models. For small L/D ratios there is a secondary circulation that acts as a refrigeration cycle, and for greater L/D ratios distribution of velocity and temperature inside the vortex tube remains the same, regardless of the stagnation point presence. It is not justified to increase the length of the vortex tube beyond 20D since the change in cold total temperature inside the vortex tube as well at the cold outlet is practically null. For L/D variation from 1.8 to 10, the cold outlet temperature changes from 270.9 K to 266.8 K, and then rises to its final value of 270.5 K. For L/D ratio from 20 to 60, the total temperature at cold end remains unchanged at 271.3 K. We obtained good results with the unit value of turbulent Prandtl number, and demonstrated that increasing the Pr-T beyond unit value is not necessary in order to numerically obtain the energy separation inside the vortex tube.
PB  - Isfahan Univ Technology, Isfahan
T2  - Journal of Applied Fluid Mechanics
T1  - Numerical Study of the L/D Ratio and Turbulent Prandtl Number Effect on Energy Separation in a Counter-Flow Vortex Tube
EP  - 1511
IS  - 5
SP  - 1503
VL  - 15
DO  - 10.47176/jafm.15.05.1168
ER  - 

@article{
author = "Burazer, Jela M. and Novković, Đorđe  and Ćoćić, Aleksandar and Bukurov, M. and Lečić, Milan",
year = "2022",
abstract = "Vortex tube is a device without moving parts with ability to separate pressurized gas into two streams: cold and hot. This is a consequence of the Eckert-Wiese effect, which is responsible for spontaneous redistribution of total energy within the flow domain. In order for vortex tubes to work properly, there are some constraints which have to be fulfilled. The most important constraint in that sense is the L/D ratio. One part of this paper is dedicated to the research of the influence of L/D ratio on the energy separation in a vortex tube, i.e. to the values of total temperatures on cold and hot outlets of the device. On the other hand, experimental research of the inner flow is quite challenging since vortex tube is a device of small dimensions. Hence, we are relaying on numerical computations. One of important quantities that has to be prescribed in these computations is the turbulent Prandtl number Pr-T. Because of that, the other part of this paper is dedicated to research of the influence of Pr-T on the results of numerical computations. The research is conducted using open-source software OpenFOAM. Turbulence is modelled using two-equation and RST models. For small L/D ratios there is a secondary circulation that acts as a refrigeration cycle, and for greater L/D ratios distribution of velocity and temperature inside the vortex tube remains the same, regardless of the stagnation point presence. It is not justified to increase the length of the vortex tube beyond 20D since the change in cold total temperature inside the vortex tube as well at the cold outlet is practically null. For L/D variation from 1.8 to 10, the cold outlet temperature changes from 270.9 K to 266.8 K, and then rises to its final value of 270.5 K. For L/D ratio from 20 to 60, the total temperature at cold end remains unchanged at 271.3 K. We obtained good results with the unit value of turbulent Prandtl number, and demonstrated that increasing the Pr-T beyond unit value is not necessary in order to numerically obtain the energy separation inside the vortex tube.",
publisher = "Isfahan Univ Technology, Isfahan",
journal = "Journal of Applied Fluid Mechanics",
title = "Numerical Study of the L/D Ratio and Turbulent Prandtl Number Effect on Energy Separation in a Counter-Flow Vortex Tube",
pages = "1511-1503",
number = "5",
volume = "15",
doi = "10.47176/jafm.15.05.1168"
}

Burazer, J. M., Novković, Đ., Ćoćić, A., Bukurov, M.,& Lečić, M.. (2022). Numerical Study of the L/D Ratio and Turbulent Prandtl Number Effect on Energy Separation in a Counter-Flow Vortex Tube. in Journal of Applied Fluid Mechanics
Isfahan Univ Technology, Isfahan., 15(5), 1503-1511.
https://doi.org/10.47176/jafm.15.05.1168

Burazer JM, Novković Đ, Ćoćić A, Bukurov M, Lečić M. Numerical Study of the L/D Ratio and Turbulent Prandtl Number Effect on Energy Separation in a Counter-Flow Vortex Tube. in Journal of Applied Fluid Mechanics. 2022;15(5):1503-1511.
doi:10.47176/jafm.15.05.1168 .

Burazer, Jela M., Novković, Đorđe , Ćoćić, Aleksandar, Bukurov, M., Lečić, Milan, "Numerical Study of the L/D Ratio and Turbulent Prandtl Number Effect on Energy Separation in a Counter-Flow Vortex Tube" in Journal of Applied Fluid Mechanics, 15, no. 5 (2022):1503-1511,
https://doi.org/10.47176/jafm.15.05.1168 . .

TY  - JOUR
AU  - Janović, Nataša
AU  - Ćoćić, Aleksandar
AU  - Stamenić, Mirjana
AU  - Janović, Aleksa
AU  - Djurić, Marija
PY  - 2020
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3379
AB  - Objectives The objective of this study was to investigate the relationship between side asymmetry in nasal resistance (NR) and severity of the nasal airway obstruction (NAO) in patients with different types of nasal septal deformity (NSD). Design Computational fluid dynamics (CFD) study. Setting The study was conducted in a tertiary medical centre. Participants The study included 232 patients, who were referred to the CT examination of the paranasal sinuses. Exclusion criteria were sinonasal and respiratory diseases that may interfere with the nasal obstruction. The presence and the type of NSD were recorded according to the Mladina's classification. Main outcome measures The presence and severity of NAO in each patient were assessed by NOSE questionnaire. Eight computational models of the nasal cavity were created from CT scans. Models represented seven Mladina's NSD types and a straight septum of a symptomless patient. CFD calculated airflow partitioning and NR for each nasal passage. Side differences in NR were calculated by the equation increment NR = NRleft - NRright. The relationship between NOSE scores, airflow partitioning and side differences in NR was explored using Spearman's correlation analysis. Results Mladina's types of NSD showed differences in airflow partitioning and the degree of side asymmetry in NR. A significant positive correlation was detected between side differences in NR and NOSE scores (R = .762, P = .028). A significant negative correlation was found between the per cent of unilateral airflow and NR (R = -.524, P = .037). Conclusions Our results demonstrated that side asymmetry in NR could explain differences in NAO severity related to the NSD type.
PB  - Wiley, Hoboken
T2  - Clinical Otolaryngology
T1  - Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study
EP  - 724
IS  - 5
SP  - 718
VL  - 45
DO  - 10.1111/coa.13563
ER  - 

@article{
author = "Janović, Nataša and Ćoćić, Aleksandar and Stamenić, Mirjana and Janović, Aleksa and Djurić, Marija",
year = "2020",
abstract = "Objectives The objective of this study was to investigate the relationship between side asymmetry in nasal resistance (NR) and severity of the nasal airway obstruction (NAO) in patients with different types of nasal septal deformity (NSD). Design Computational fluid dynamics (CFD) study. Setting The study was conducted in a tertiary medical centre. Participants The study included 232 patients, who were referred to the CT examination of the paranasal sinuses. Exclusion criteria were sinonasal and respiratory diseases that may interfere with the nasal obstruction. The presence and the type of NSD were recorded according to the Mladina's classification. Main outcome measures The presence and severity of NAO in each patient were assessed by NOSE questionnaire. Eight computational models of the nasal cavity were created from CT scans. Models represented seven Mladina's NSD types and a straight septum of a symptomless patient. CFD calculated airflow partitioning and NR for each nasal passage. Side differences in NR were calculated by the equation increment NR = NRleft - NRright. The relationship between NOSE scores, airflow partitioning and side differences in NR was explored using Spearman's correlation analysis. Results Mladina's types of NSD showed differences in airflow partitioning and the degree of side asymmetry in NR. A significant positive correlation was detected between side differences in NR and NOSE scores (R = .762, P = .028). A significant negative correlation was found between the per cent of unilateral airflow and NR (R = -.524, P = .037). Conclusions Our results demonstrated that side asymmetry in NR could explain differences in NAO severity related to the NSD type.",
publisher = "Wiley, Hoboken",
journal = "Clinical Otolaryngology",
title = "Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study",
pages = "724-718",
number = "5",
volume = "45",
doi = "10.1111/coa.13563"
}

Janović, N., Ćoćić, A., Stamenić, M., Janović, A.,& Djurić, M.. (2020). Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study. in Clinical Otolaryngology
Wiley, Hoboken., 45(5), 718-724.
https://doi.org/10.1111/coa.13563

Janović N, Ćoćić A, Stamenić M, Janović A, Djurić M. Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study. in Clinical Otolaryngology. 2020;45(5):718-724.
doi:10.1111/coa.13563 .

Janović, Nataša, Ćoćić, Aleksandar, Stamenić, Mirjana, Janović, Aleksa, Djurić, Marija, "Side asymmetry in nasal resistance correlate with nasal obstruction severity in patients with septal deformities: Computational fluid dynamics study" in Clinical Otolaryngology, 45, no. 5 (2020):718-724,
https://doi.org/10.1111/coa.13563 . .

TY  - CONF
AU  - Raković, Milan
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2019
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6209
AB  - Numerical investigation of the flow structure and computations of drag force around Generic
Conventional Model (GCM) of tractor-trailer is analyzed in this paper. Starting from original GCM,
three additional changes on geometry have been made, and external air flow around all the models has been simulated for four different cruising speeds in open road conditions. OpenFOAM, an open-source CFD software has been used in that purpose, with RANS approach and k-ω SST model. Results shows reductions in the drag from 17-26% in comparison to the drag of the original model. Obtained results on drag reduction and drag coefficients are in agreement with the results from other authors on similar models of tractor-trailer.
C3  - 7th International Congress of Serbian Society of Mechanics
T1  - Numerical study on aerodynamic drag reduction of a tractor-trailer model
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6209
ER  - 

@conference{
author = "Raković, Milan and Ćoćić, Aleksandar and Lečić, Milan",
year = "2019",
abstract = "Numerical investigation of the flow structure and computations of drag force around Generic
Conventional Model (GCM) of tractor-trailer is analyzed in this paper. Starting from original GCM,
three additional changes on geometry have been made, and external air flow around all the models has been simulated for four different cruising speeds in open road conditions. OpenFOAM, an open-source CFD software has been used in that purpose, with RANS approach and k-ω SST model. Results shows reductions in the drag from 17-26% in comparison to the drag of the original model. Obtained results on drag reduction and drag coefficients are in agreement with the results from other authors on similar models of tractor-trailer.",
journal = "7th International Congress of Serbian Society of Mechanics",
title = "Numerical study on aerodynamic drag reduction of a tractor-trailer model",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6209"
}

Raković, M., Ćoćić, A.,& Lečić, M.. (2019). Numerical study on aerodynamic drag reduction of a tractor-trailer model. in 7th International Congress of Serbian Society of Mechanics.
https://hdl.handle.net/21.15107/rcub_machinery_6209

Raković M, Ćoćić A, Lečić M. Numerical study on aerodynamic drag reduction of a tractor-trailer model. in 7th International Congress of Serbian Society of Mechanics. 2019;.
https://hdl.handle.net/21.15107/rcub_machinery_6209 .

Raković, Milan, Ćoćić, Aleksandar, Lečić, Milan, "Numerical study on aerodynamic drag reduction of a tractor-trailer model" in 7th International Congress of Serbian Society of Mechanics (2019),
https://hdl.handle.net/21.15107/rcub_machinery_6209 .

TY  - CONF
AU  - Novković, Đorđe
AU  - Burazer, Jela
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2019
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5586
PB  - Serbian Society of Mechanics, Belgrade
C3  - 7th International Congress of Serbian Society of Mechanics
T1  - Implementation of Hamba k-epsilon Turbulence Model in OpenFOAM Software
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5586
ER  - 

@conference{
author = "Novković, Đorđe and Burazer, Jela and Ćoćić, Aleksandar and Lečić, Milan",
year = "2019",
publisher = "Serbian Society of Mechanics, Belgrade",
journal = "7th International Congress of Serbian Society of Mechanics",
title = "Implementation of Hamba k-epsilon Turbulence Model in OpenFOAM Software",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5586"
}

Novković, Đ., Burazer, J., Ćoćić, A.,& Lečić, M.. (2019). Implementation of Hamba k-epsilon Turbulence Model in OpenFOAM Software. in 7th International Congress of Serbian Society of Mechanics
Serbian Society of Mechanics, Belgrade..
https://hdl.handle.net/21.15107/rcub_machinery_5586

Novković Đ, Burazer J, Ćoćić A, Lečić M. Implementation of Hamba k-epsilon Turbulence Model in OpenFOAM Software. in 7th International Congress of Serbian Society of Mechanics. 2019;.
https://hdl.handle.net/21.15107/rcub_machinery_5586 .

Novković, Đorđe, Burazer, Jela, Ćoćić, Aleksandar, Lečić, Milan, "Implementation of Hamba k-epsilon Turbulence Model in OpenFOAM Software" in 7th International Congress of Serbian Society of Mechanics (2019),
https://hdl.handle.net/21.15107/rcub_machinery_5586 .

TY  - CONF
AU  - Ćoćić, Aleksandar
AU  - Đorđević, Vladan
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5523
AB  - Solar updraft power technology is attracting interest in many
  regions worldwide, being a compelling prospect for producing 
  clean and renewable energy. Very import operational parameters of 
  solar chimney power plant (SCPP) are mass flow rate and pressure
  difference inside the chimney. Based on the assumption of
  one-dimensional flow, a comprehensive mathematical model for
  buoyancy driven air flow inside the SCPP is developed. It consists
  of system of nonlinear differential equations which describes the
  flow inside collector and the chimney, and algebraic equations which
  describes the flow in collector to chimney transition section and
  turbines. Validity of the model is confirmed by numerical solution
  of the equations for the case of Manzaneres SCPP, where good
  agreement is found between obtained solution and available
  experimental data. Additionally, nonlinear differential equations
  that describes the flow in the chimney are further analyzed
  analytically. A perturbational approach based on Rayleigh-Janzen
  perturbation scheme is developed, in which effects of gravity and
  variability of cross section are considered in first approximation,
  while inertia and friction are treated in second approximation. For
  both approximation, the exact analytical solution is found. That
  fact enables very good insight into the role of each important
  parameter that governs the flow inside the chimney, which is also
  elaborated. This theory also enables evaluation of chimney shape
  that affects the flow in a way  which can be prescribed in advance.
C3  - Conference on Modelling Fluid Flow (CMFF’18)
T1  - Modeling and Calculation of Air Flow in Solar Chimney Power Plant
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5523
ER  - 

@conference{
author = "Ćoćić, Aleksandar and Đorđević, Vladan",
year = "2018",
abstract = "Solar updraft power technology is attracting interest in many
  regions worldwide, being a compelling prospect for producing 
  clean and renewable energy. Very import operational parameters of 
  solar chimney power plant (SCPP) are mass flow rate and pressure
  difference inside the chimney. Based on the assumption of
  one-dimensional flow, a comprehensive mathematical model for
  buoyancy driven air flow inside the SCPP is developed. It consists
  of system of nonlinear differential equations which describes the
  flow inside collector and the chimney, and algebraic equations which
  describes the flow in collector to chimney transition section and
  turbines. Validity of the model is confirmed by numerical solution
  of the equations for the case of Manzaneres SCPP, where good
  agreement is found between obtained solution and available
  experimental data. Additionally, nonlinear differential equations
  that describes the flow in the chimney are further analyzed
  analytically. A perturbational approach based on Rayleigh-Janzen
  perturbation scheme is developed, in which effects of gravity and
  variability of cross section are considered in first approximation,
  while inertia and friction are treated in second approximation. For
  both approximation, the exact analytical solution is found. That
  fact enables very good insight into the role of each important
  parameter that governs the flow inside the chimney, which is also
  elaborated. This theory also enables evaluation of chimney shape
  that affects the flow in a way  which can be prescribed in advance.",
journal = "Conference on Modelling Fluid Flow (CMFF’18)",
title = "Modeling and Calculation of Air Flow in Solar Chimney Power Plant",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5523"
}

Ćoćić, A.,& Đorđević, V.. (2018). Modeling and Calculation of Air Flow in Solar Chimney Power Plant. in Conference on Modelling Fluid Flow (CMFF’18).
https://hdl.handle.net/21.15107/rcub_machinery_5523

Ćoćić A, Đorđević V. Modeling and Calculation of Air Flow in Solar Chimney Power Plant. in Conference on Modelling Fluid Flow (CMFF’18). 2018;.
https://hdl.handle.net/21.15107/rcub_machinery_5523 .

Ćoćić, Aleksandar, Đorđević, Vladan, "Modeling and Calculation of Air Flow in Solar Chimney Power Plant" in Conference on Modelling Fluid Flow (CMFF’18) (2018),
https://hdl.handle.net/21.15107/rcub_machinery_5523 .

TY  - CONF
AU  - Raković, Milan
AU  - Ćoćić, Aleksandar
AU  - Crnojević, Cvetko
AU  - Lečić, Milan
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6215
AB  - Flow past a sphere represents one of the classical problems in fluid dynamics. It is extensively investigated, starting from analytical solution of Navier-Stokes equations in case of creeping flow (Re<<1),  and later on for various ranges of Reynolds number, mostly using experimental methods. In recent decades, with advances in CFD (Computational Fluid Dynamics) this problem is additionaly investigated numerically. In this study, flow past a sphere for broad range of Reynolds number (10 < Re < 200000) is analyzed using open-source software OpenFOAM. Flow is treated as incompressible and for turbulent regime RANS modeling approach is addopted, with comparative analysis for k-e and k-w SST. Unsteady vortex shedding effects  are also analyzed, for both regimes of the flow (laminar and turbulent). Extensive comparisons were made between the predicted and available experimental results for drag coefficient and good agreement is found for almost the whole range of Reynolds number.
C3  - ICAS 2018 Book of abstracts
T1  - Numerical Study of Flow Past Solid Sphere using OpenFOAM
SP  - 164
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6215
ER  - 

@conference{
author = "Raković, Milan and Ćoćić, Aleksandar and Crnojević, Cvetko and Lečić, Milan",
year = "2018",
abstract = "Flow past a sphere represents one of the classical problems in fluid dynamics. It is extensively investigated, starting from analytical solution of Navier-Stokes equations in case of creeping flow (Re<<1),  and later on for various ranges of Reynolds number, mostly using experimental methods. In recent decades, with advances in CFD (Computational Fluid Dynamics) this problem is additionaly investigated numerically. In this study, flow past a sphere for broad range of Reynolds number (10 < Re < 200000) is analyzed using open-source software OpenFOAM. Flow is treated as incompressible and for turbulent regime RANS modeling approach is addopted, with comparative analysis for k-e and k-w SST. Unsteady vortex shedding effects  are also analyzed, for both regimes of the flow (laminar and turbulent). Extensive comparisons were made between the predicted and available experimental results for drag coefficient and good agreement is found for almost the whole range of Reynolds number.",
journal = "ICAS 2018 Book of abstracts",
title = "Numerical Study of Flow Past Solid Sphere using OpenFOAM",
pages = "164",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6215"
}

Raković, M., Ćoćić, A., Crnojević, C.,& Lečić, M.. (2018). Numerical Study of Flow Past Solid Sphere using OpenFOAM. in ICAS 2018 Book of abstracts, 164.
https://hdl.handle.net/21.15107/rcub_machinery_6215

Raković M, Ćoćić A, Crnojević C, Lečić M. Numerical Study of Flow Past Solid Sphere using OpenFOAM. in ICAS 2018 Book of abstracts. 2018;:164.
https://hdl.handle.net/21.15107/rcub_machinery_6215 .

Raković, Milan, Ćoćić, Aleksandar, Crnojević, Cvetko, Lečić, Milan, "Numerical Study of Flow Past Solid Sphere using OpenFOAM" in ICAS 2018 Book of abstracts (2018):164,
https://hdl.handle.net/21.15107/rcub_machinery_6215 .

TY  - JOUR
AU  - Novković, Đorđe 
AU  - Burazer, Jela M.
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2849
AB  - This paper presents research regarding the influence of turbulent kinetic energy (TKE) level on accuracy of Reynolds averaged Navier-Stokes (RANS) based turbulence models. A theoretical analysis of influence TKE level on accuracy of the RANS turbulence models has been performed according to the Boussinesq hypothesis definition. After that, this theoretical analysis has been investigated by comparison of numerically and experimentally obtained results on the test case of a steady-state incompressible swirl-free flow in a straight conical diffuser named Azad diffuser. Numerical calculations have been performed using the OpenFOAM CFD software and first and second-order closure turbulence models. TKE level, velocity profiles and Reynolds stresses have been calculated downstream in four different cross sections of the diffuser. Certain conclusions about modeling turbulent flows by k - epsilon and LRR turbulence models have been made by comparing the velocity profiles, TKE distribution and Reynolds stresses on the selected cross sections.
PB  - Srpsko društvo za mehaniku, Beograd
T2  - Theoretical and Applied Mechanics
T1  - On the influence of turbulent kinetic energy level on accuracy of k - epsilon and lrr turbulence models
EP  - 149
IS  - 2
SP  - 139
VL  - 45
DO  - 10.2298/TAM171201009N
ER  - 

@article{
author = "Novković, Đorđe  and Burazer, Jela M. and Ćoćić, Aleksandar and Lečić, Milan",
year = "2018",
abstract = "This paper presents research regarding the influence of turbulent kinetic energy (TKE) level on accuracy of Reynolds averaged Navier-Stokes (RANS) based turbulence models. A theoretical analysis of influence TKE level on accuracy of the RANS turbulence models has been performed according to the Boussinesq hypothesis definition. After that, this theoretical analysis has been investigated by comparison of numerically and experimentally obtained results on the test case of a steady-state incompressible swirl-free flow in a straight conical diffuser named Azad diffuser. Numerical calculations have been performed using the OpenFOAM CFD software and first and second-order closure turbulence models. TKE level, velocity profiles and Reynolds stresses have been calculated downstream in four different cross sections of the diffuser. Certain conclusions about modeling turbulent flows by k - epsilon and LRR turbulence models have been made by comparing the velocity profiles, TKE distribution and Reynolds stresses on the selected cross sections.",
publisher = "Srpsko društvo za mehaniku, Beograd",
journal = "Theoretical and Applied Mechanics",
title = "On the influence of turbulent kinetic energy level on accuracy of k - epsilon and lrr turbulence models",
pages = "149-139",
number = "2",
volume = "45",
doi = "10.2298/TAM171201009N"
}

Novković, Đ., Burazer, J. M., Ćoćić, A.,& Lečić, M.. (2018). On the influence of turbulent kinetic energy level on accuracy of k - epsilon and lrr turbulence models. in Theoretical and Applied Mechanics
Srpsko društvo za mehaniku, Beograd., 45(2), 139-149.
https://doi.org/10.2298/TAM171201009N

Novković Đ, Burazer JM, Ćoćić A, Lečić M. On the influence of turbulent kinetic energy level on accuracy of k - epsilon and lrr turbulence models. in Theoretical and Applied Mechanics. 2018;45(2):139-149.
doi:10.2298/TAM171201009N .

Novković, Đorđe , Burazer, Jela M., Ćoćić, Aleksandar, Lečić, Milan, "On the influence of turbulent kinetic energy level on accuracy of k - epsilon and lrr turbulence models" in Theoretical and Applied Mechanics, 45, no. 2 (2018):139-149,
https://doi.org/10.2298/TAM171201009N . .

TY  - JOUR
AU  - Gašić, Vlada
AU  - Ćoćić, Aleksandar
AU  - Anđelić, Nina
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2817
AB  - U ovom radu se analizira uticaj horizontalnih inercijalnih sila na konzolne nosače sa promenljivim poprečnim presekom oblika I-profila. Razmatra se varijacija preseka koja uključuje promenu visine preseka, kao najpraktičnije varijante pri projektovanju nosača dizalica. Zbog složenosti postavljenog problema koji uključuje problem ograničenog uvijanja, statički odzivi su dobijeni numeričkim metodama. Modeli nosača su usvojeni prema poznatim konstrukcionom preporukama za varijaciju nosača, sa ciljem praktične primene kod konstrukcija konzolnih dizalica. Poređenje rezultata je izvršeno sa poznatim vrednostima efekata uvojnog savijanja kod nosača uniformnog poprečnog preseka. Sa aspekta postavljenog problema i izabranih modela nosača, prikazane su prednosti korišćenja nosača sa promenljivim poprečnim presekom.
AB  - The problem of torsion due to horizontal inertial effects is considered at cantilever beam with variable I-section. Linear variation of height is concerned as most practical one for the design of cantilever beams. The solution for adopted cases of beams is obtained numerically, according to the complexity of the given ordinary differential equation which deals with pure torsion along with warping torsion. The models are based on known tailor-made beams with possibility for application in design of jib cranes, as practical aspect of this work. The comparison of results is done with uniform cantilever beam models which can be used as one way for verification of stress state of variable cantilever beams subjected to bending with torsion. The obtained results show corresponding advantages of usage of variable sections.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - Uticaj horizontalnih inercijalnih sila kod konzolnih nosača sa promenljivim poprečnim presekom
T1  - Consideration of the horizontal inertial effects at cantilever beams with nonuniform open sections
EP  - 346
IS  - 3
SP  - 342
VL  - 46
DO  - 10.5937/fmet1803342G
ER  - 

@article{
author = "Gašić, Vlada and Ćoćić, Aleksandar and Anđelić, Nina",
year = "2018",
abstract = "U ovom radu se analizira uticaj horizontalnih inercijalnih sila na konzolne nosače sa promenljivim poprečnim presekom oblika I-profila. Razmatra se varijacija preseka koja uključuje promenu visine preseka, kao najpraktičnije varijante pri projektovanju nosača dizalica. Zbog složenosti postavljenog problema koji uključuje problem ograničenog uvijanja, statički odzivi su dobijeni numeričkim metodama. Modeli nosača su usvojeni prema poznatim konstrukcionom preporukama za varijaciju nosača, sa ciljem praktične primene kod konstrukcija konzolnih dizalica. Poređenje rezultata je izvršeno sa poznatim vrednostima efekata uvojnog savijanja kod nosača uniformnog poprečnog preseka. Sa aspekta postavljenog problema i izabranih modela nosača, prikazane su prednosti korišćenja nosača sa promenljivim poprečnim presekom., The problem of torsion due to horizontal inertial effects is considered at cantilever beam with variable I-section. Linear variation of height is concerned as most practical one for the design of cantilever beams. The solution for adopted cases of beams is obtained numerically, according to the complexity of the given ordinary differential equation which deals with pure torsion along with warping torsion. The models are based on known tailor-made beams with possibility for application in design of jib cranes, as practical aspect of this work. The comparison of results is done with uniform cantilever beam models which can be used as one way for verification of stress state of variable cantilever beams subjected to bending with torsion. The obtained results show corresponding advantages of usage of variable sections.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "Uticaj horizontalnih inercijalnih sila kod konzolnih nosača sa promenljivim poprečnim presekom, Consideration of the horizontal inertial effects at cantilever beams with nonuniform open sections",
pages = "346-342",
number = "3",
volume = "46",
doi = "10.5937/fmet1803342G"
}

Gašić, V., Ćoćić, A.,& Anđelić, N.. (2018). Uticaj horizontalnih inercijalnih sila kod konzolnih nosača sa promenljivim poprečnim presekom. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 46(3), 342-346.
https://doi.org/10.5937/fmet1803342G

Gašić V, Ćoćić A, Anđelić N. Uticaj horizontalnih inercijalnih sila kod konzolnih nosača sa promenljivim poprečnim presekom. in FME Transactions. 2018;46(3):342-346.
doi:10.5937/fmet1803342G .

Gašić, Vlada, Ćoćić, Aleksandar, Anđelić, Nina, "Uticaj horizontalnih inercijalnih sila kod konzolnih nosača sa promenljivim poprečnim presekom" in FME Transactions, 46, no. 3 (2018):342-346,
https://doi.org/10.5937/fmet1803342G . .

TY  - CONF
AU  - Gašić, Vlada
AU  - Ćoćić, Aleksandar
AU  - Anđelić, Nina
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/4573
AB  - The problem of torsion of the I-section beam is considered in this work,
with emphasis on the variable cross section of the beam. Linear variation
of height is concerned as most practical one for the design of cantilever
beams. The solution for adopted cases of beams is obtained numerically,
according to the given ordinary differential equation which deals with pure
torsion along with warping torsion. The models are based on practical
tailore-made beams. The comparison of results is done with uniform
cantilever beam models which can be used as one view for stress check of
cantilever beams subjected to bending with torsion.
PB  - University of Belgrade: Faculty of Mechanical Engineering
C3  - Proceedings of XXII International Conference on "Material Handling, Constructions and Logistics" - MHCL 2017
T1  - Warping torsion of non-uniform thin-walled open section at cantilever beams
EP  - 244
SP  - 241
UR  - https://hdl.handle.net/21.15107/rcub_machinery_4573
ER  - 

@conference{
author = "Gašić, Vlada and Ćoćić, Aleksandar and Anđelić, Nina",
year = "2017",
abstract = "The problem of torsion of the I-section beam is considered in this work,
with emphasis on the variable cross section of the beam. Linear variation
of height is concerned as most practical one for the design of cantilever
beams. The solution for adopted cases of beams is obtained numerically,
according to the given ordinary differential equation which deals with pure
torsion along with warping torsion. The models are based on practical
tailore-made beams. The comparison of results is done with uniform
cantilever beam models which can be used as one view for stress check of
cantilever beams subjected to bending with torsion.",
publisher = "University of Belgrade: Faculty of Mechanical Engineering",
journal = "Proceedings of XXII International Conference on "Material Handling, Constructions and Logistics" - MHCL 2017",
title = "Warping torsion of non-uniform thin-walled open section at cantilever beams",
pages = "244-241",
url = "https://hdl.handle.net/21.15107/rcub_machinery_4573"
}

Gašić, V., Ćoćić, A.,& Anđelić, N.. (2017). Warping torsion of non-uniform thin-walled open section at cantilever beams. in Proceedings of XXII International Conference on "Material Handling, Constructions and Logistics" - MHCL 2017
University of Belgrade: Faculty of Mechanical Engineering., 241-244.
https://hdl.handle.net/21.15107/rcub_machinery_4573

Gašić V, Ćoćić A, Anđelić N. Warping torsion of non-uniform thin-walled open section at cantilever beams. in Proceedings of XXII International Conference on "Material Handling, Constructions and Logistics" - MHCL 2017. 2017;:241-244.
https://hdl.handle.net/21.15107/rcub_machinery_4573 .

Gašić, Vlada, Ćoćić, Aleksandar, Anđelić, Nina, "Warping torsion of non-uniform thin-walled open section at cantilever beams" in Proceedings of XXII International Conference on "Material Handling, Constructions and Logistics" - MHCL 2017 (2017):241-244,
https://hdl.handle.net/21.15107/rcub_machinery_4573 .

TY  - CONF
AU  - Novković, Đorđe
AU  - Burazer, Jela
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5585
C3  - 6th International Congress of Serbian Society of Mechanics
T1  - Numerical Research of Swirl-Free flow in Azad Diffuser
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5585
ER  - 

@conference{
author = "Novković, Đorđe and Burazer, Jela and Ćoćić, Aleksandar and Lečić, Milan",
year = "2017",
journal = "6th International Congress of Serbian Society of Mechanics",
title = "Numerical Research of Swirl-Free flow in Azad Diffuser",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5585"
}

Novković, Đ., Burazer, J., Ćoćić, A.,& Lečić, M.. (2017). Numerical Research of Swirl-Free flow in Azad Diffuser. in 6th International Congress of Serbian Society of Mechanics.
https://hdl.handle.net/21.15107/rcub_machinery_5585

Novković Đ, Burazer J, Ćoćić A, Lečić M. Numerical Research of Swirl-Free flow in Azad Diffuser. in 6th International Congress of Serbian Society of Mechanics. 2017;.
https://hdl.handle.net/21.15107/rcub_machinery_5585 .

Novković, Đorđe, Burazer, Jela, Ćoćić, Aleksandar, Lečić, Milan, "Numerical Research of Swirl-Free flow in Azad Diffuser" in 6th International Congress of Serbian Society of Mechanics (2017),
https://hdl.handle.net/21.15107/rcub_machinery_5585 .

TY  - CONF
AU  - Ćoćić, Aleksandar
AU  - Raković, Milan
AU  - Ilić, Dejan
AU  - Lečić, Milan
PY  - 2017
UR  - http://www.ssm.kg.ac.rs/archive/congress_2017/pdf/Technical_programme_v4.pdf
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/4937
AB  - Turbulent, incompressible flow through orifice flow meter is numerically investigated using
OpenFOAM software. Turbulence is modeled using RANS approach, and three turbulence models are tested: standard k-e , k −w and Launder Sharma model. Results for pressure drop on the orifice are compared to experimental results and good agreement is found for all turbulent models, with the most accurate results obtained with k−e model. Velocity and pressure distribution in whole computational domain is analyzed, with special attention to the region in proximity to the orifice where primary and secondary vortex structures are detected. Additionally, numerical computations are also performed on automatically generated mesh using snappyHexMesh utility and similar results for the pressure drop are obtained as the ones on the block-structured grid.
PB  - Srpsko društvo za Mehaniku
C3  - 6th International Congress of Serbian Society of Mechanics
T1  - Numerical computations of turbulent flow through orifice flowmeter
UR  - https://hdl.handle.net/21.15107/rcub_machinery_4937
ER  - 

@conference{
author = "Ćoćić, Aleksandar and Raković, Milan and Ilić, Dejan and Lečić, Milan",
year = "2017",
abstract = "Turbulent, incompressible flow through orifice flow meter is numerically investigated using
OpenFOAM software. Turbulence is modeled using RANS approach, and three turbulence models are tested: standard k-e , k −w and Launder Sharma model. Results for pressure drop on the orifice are compared to experimental results and good agreement is found for all turbulent models, with the most accurate results obtained with k−e model. Velocity and pressure distribution in whole computational domain is analyzed, with special attention to the region in proximity to the orifice where primary and secondary vortex structures are detected. Additionally, numerical computations are also performed on automatically generated mesh using snappyHexMesh utility and similar results for the pressure drop are obtained as the ones on the block-structured grid.",
publisher = "Srpsko društvo za Mehaniku",
journal = "6th International Congress of Serbian Society of Mechanics",
title = "Numerical computations of turbulent flow through orifice flowmeter",
url = "https://hdl.handle.net/21.15107/rcub_machinery_4937"
}

Ćoćić, A., Raković, M., Ilić, D.,& Lečić, M.. (2017). Numerical computations of turbulent flow through orifice flowmeter. in 6th International Congress of Serbian Society of Mechanics
Srpsko društvo za Mehaniku..
https://hdl.handle.net/21.15107/rcub_machinery_4937

Ćoćić A, Raković M, Ilić D, Lečić M. Numerical computations of turbulent flow through orifice flowmeter. in 6th International Congress of Serbian Society of Mechanics. 2017;.
https://hdl.handle.net/21.15107/rcub_machinery_4937 .

Ćoćić, Aleksandar, Raković, Milan, Ilić, Dejan, Lečić, Milan, "Numerical computations of turbulent flow through orifice flowmeter" in 6th International Congress of Serbian Society of Mechanics (2017),
https://hdl.handle.net/21.15107/rcub_machinery_4937 .

TY  - JOUR
AU  - Lečić, Milan
AU  - Ćoćić, Aleksandar
AU  - Burazer, Jela M.
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2653
AB  - This paper presents results of our own velocity field measurements in a straight pipe swirl flow. These studies were conducted using an originally designed hot wire probe. Due to the specially tailored shape of the probe, it was possible to get four measurement points in the viscous sublayer. The time-averaged velocity field and the statistical moments of the second and third order are calculated based on the measured velocity components. Mathematical and physical interpretations of statistical characteristics and structures of turbulent swirl flow in the time domain are presented. On the basis of these results, deeper insight into turbulent transport processes can be obtained, as well as useful conclusions necessary for turbulent swirl flows modeling.
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe
EP  - S704
SP  - S691
VL  - 21
DO  - 10.2298/TSCI160201191L
ER  - 

@article{
author = "Lečić, Milan and Ćoćić, Aleksandar and Burazer, Jela M.",
year = "2017",
abstract = "This paper presents results of our own velocity field measurements in a straight pipe swirl flow. These studies were conducted using an originally designed hot wire probe. Due to the specially tailored shape of the probe, it was possible to get four measurement points in the viscous sublayer. The time-averaged velocity field and the statistical moments of the second and third order are calculated based on the measured velocity components. Mathematical and physical interpretations of statistical characteristics and structures of turbulent swirl flow in the time domain are presented. On the basis of these results, deeper insight into turbulent transport processes can be obtained, as well as useful conclusions necessary for turbulent swirl flows modeling.",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe",
pages = "S704-S691",
volume = "21",
doi = "10.2298/TSCI160201191L"
}

Lečić, M., Ćoćić, A.,& Burazer, J. M.. (2017). An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 21, S691-S704.
https://doi.org/10.2298/TSCI160201191L

Lečić M, Ćoćić A, Burazer JM. An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe. in Thermal Science. 2017;21:S691-S704.
doi:10.2298/TSCI160201191L .

Lečić, Milan, Ćoćić, Aleksandar, Burazer, Jela M., "An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe" in Thermal Science, 21 (2017):S691-S704,
https://doi.org/10.2298/TSCI160201191L . .

TY  - JOUR
AU  - Đorđević, Vladan D.
AU  - Ćoćić, Aleksandar
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2638
AB  - Buoyancy driven, adiabatic and compressible flow in relatively high solar chimneys is treated in the paper analytically by using one-dimensional model of flow. General equations written suitably in a non-dimensional form are used for a qualitative discussion pertaining to the mutual effects of gravity, viscosity and varying cross section of the chimney. It is shown that in case of low Mach number flow these equations possess exact solutions obtainable by ordinary mathematical methods for any given chimney shape. Also shown, and demonstrated on an example, is the procedure of evaluation of the chimney shape that satisfies a condition imposed beforehand upon the flow. For better insight into the role of various parameters the solutions are presented in the form of power series expansions.
PB  - Srpsko društvo za mehaniku, Beograd
T2  - Theoretical and Applied Mechanics
T1  - Compressible flow through solar chimneys with variable cross section - an exact solution
EP  - 228
IS  - 2
SP  - 215
VL  - 44
DO  - 10.2298/TAM170815014D
ER  - 

@article{
author = "Đorđević, Vladan D. and Ćoćić, Aleksandar",
year = "2017",
abstract = "Buoyancy driven, adiabatic and compressible flow in relatively high solar chimneys is treated in the paper analytically by using one-dimensional model of flow. General equations written suitably in a non-dimensional form are used for a qualitative discussion pertaining to the mutual effects of gravity, viscosity and varying cross section of the chimney. It is shown that in case of low Mach number flow these equations possess exact solutions obtainable by ordinary mathematical methods for any given chimney shape. Also shown, and demonstrated on an example, is the procedure of evaluation of the chimney shape that satisfies a condition imposed beforehand upon the flow. For better insight into the role of various parameters the solutions are presented in the form of power series expansions.",
publisher = "Srpsko društvo za mehaniku, Beograd",
journal = "Theoretical and Applied Mechanics",
title = "Compressible flow through solar chimneys with variable cross section - an exact solution",
pages = "228-215",
number = "2",
volume = "44",
doi = "10.2298/TAM170815014D"
}

Đorđević, V. D.,& Ćoćić, A.. (2017). Compressible flow through solar chimneys with variable cross section - an exact solution. in Theoretical and Applied Mechanics
Srpsko društvo za mehaniku, Beograd., 44(2), 215-228.
https://doi.org/10.2298/TAM170815014D

Đorđević VD, Ćoćić A. Compressible flow through solar chimneys with variable cross section - an exact solution. in Theoretical and Applied Mechanics. 2017;44(2):215-228.
doi:10.2298/TAM170815014D .

Đorđević, Vladan D., Ćoćić, Aleksandar, "Compressible flow through solar chimneys with variable cross section - an exact solution" in Theoretical and Applied Mechanics, 44, no. 2 (2017):215-228,
https://doi.org/10.2298/TAM170815014D . .

TY  - JOUR
AU  - Burazer, Jela M.
AU  - Ćoćić, Aleksandar
AU  - Lečić, Milan
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2605
AB  - The work presented in this paper is dealing with numerical simulation of energy separation mechanism and flow phenomena within a Ranque-Hilsch vortex tube. Simulation of turbulent, compressible, highly swirling flow inside vortex tube is performed using RANS approach, with Favre averaged conservation equations. For turbulence closure, k-epsilon and k-omega shear-stress transport models are used It is assumed that the mean flow is axisymmetric, so the 2-D computational domain is used. Computations were performed using open-source CFD software Open FOAM All compressible solvers available within OpenFOAM were tested, and it was found that most of the solvers cannot predict energy separation. Code of two chosen solvers, which proved as the most robust, is modified in terms of mean energy equation implementation. Newly created solvers predict physically accepted behavior in vortex tube, with good agreement with experimental results. Comparison between performances of solvers is also presented
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - Numerical research of the compressible flow in a vortex tube using openfoam software
EP  - S758
SP  - S745
VL  - 21
DO  - 10.2298/TSCI160223195B
ER  - 

@article{
author = "Burazer, Jela M. and Ćoćić, Aleksandar and Lečić, Milan",
year = "2017",
abstract = "The work presented in this paper is dealing with numerical simulation of energy separation mechanism and flow phenomena within a Ranque-Hilsch vortex tube. Simulation of turbulent, compressible, highly swirling flow inside vortex tube is performed using RANS approach, with Favre averaged conservation equations. For turbulence closure, k-epsilon and k-omega shear-stress transport models are used It is assumed that the mean flow is axisymmetric, so the 2-D computational domain is used. Computations were performed using open-source CFD software Open FOAM All compressible solvers available within OpenFOAM were tested, and it was found that most of the solvers cannot predict energy separation. Code of two chosen solvers, which proved as the most robust, is modified in terms of mean energy equation implementation. Newly created solvers predict physically accepted behavior in vortex tube, with good agreement with experimental results. Comparison between performances of solvers is also presented",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "Numerical research of the compressible flow in a vortex tube using openfoam software",
pages = "S758-S745",
volume = "21",
doi = "10.2298/TSCI160223195B"
}

Burazer, J. M., Ćoćić, A.,& Lečić, M.. (2017). Numerical research of the compressible flow in a vortex tube using openfoam software. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 21, S745-S758.
https://doi.org/10.2298/TSCI160223195B

Burazer JM, Ćoćić A, Lečić M. Numerical research of the compressible flow in a vortex tube using openfoam software. in Thermal Science. 2017;21:S745-S758.
doi:10.2298/TSCI160223195B .

Burazer, Jela M., Ćoćić, Aleksandar, Lečić, Milan, "Numerical research of the compressible flow in a vortex tube using openfoam software" in Thermal Science, 21 (2017):S745-S758,
https://doi.org/10.2298/TSCI160223195B . .

TY  - JOUR
AU  - Novković, Đorđe 
AU  - Burazer, Jela M.
AU  - Ćoćić, Aleksandar
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2604
AB  - Numerical flow simulations have been carried out in order to analyze the possibilities of numerical prediction of a steady-state incompressible air flow through a conical diffuser named Azad diffuser. The spreading angle of this diffuser is 8 degrees and it has cylindrical parts of the constant diameter in the inlet and outlet flow zones. Numerical analysis has been performed by the use of the standard k-epsilon turbulence model. The simulations have been performed using the Ansys CFX and the OpenFOAM software for cases of 2-D and 3-D computational domains. In both cases a Ally developed turbulent flow at the inlet section of diffuser is present. The numerical flow simulation in a 2-D computational domain has been performed under the assumption of an axisymmetric flow in the diffuser. Numerically obtained results have been compared with experimental data. Results obtained with these two softwares have also been mutually compared. At the end the results obtained by CFD for the cases of 2-D and 3-D computational domains have been mutually compared, and the advantages and disadvantages of performing numerical simulations under the assumption of an axisymmetric flow in the diffuser have been analyzed.
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - Comparison of different cfd software performances in the case of an incompressible air flow through a straight conical diffuser
EP  - S874
SP  - S863
VL  - 21
DO  - 10.2298/TSCI161020329N
ER  - 

@article{
author = "Novković, Đorđe  and Burazer, Jela M. and Ćoćić, Aleksandar",
year = "2017",
abstract = "Numerical flow simulations have been carried out in order to analyze the possibilities of numerical prediction of a steady-state incompressible air flow through a conical diffuser named Azad diffuser. The spreading angle of this diffuser is 8 degrees and it has cylindrical parts of the constant diameter in the inlet and outlet flow zones. Numerical analysis has been performed by the use of the standard k-epsilon turbulence model. The simulations have been performed using the Ansys CFX and the OpenFOAM software for cases of 2-D and 3-D computational domains. In both cases a Ally developed turbulent flow at the inlet section of diffuser is present. The numerical flow simulation in a 2-D computational domain has been performed under the assumption of an axisymmetric flow in the diffuser. Numerically obtained results have been compared with experimental data. Results obtained with these two softwares have also been mutually compared. At the end the results obtained by CFD for the cases of 2-D and 3-D computational domains have been mutually compared, and the advantages and disadvantages of performing numerical simulations under the assumption of an axisymmetric flow in the diffuser have been analyzed.",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "Comparison of different cfd software performances in the case of an incompressible air flow through a straight conical diffuser",
pages = "S874-S863",
volume = "21",
doi = "10.2298/TSCI161020329N"
}

Novković, Đ., Burazer, J. M.,& Ćoćić, A.. (2017). Comparison of different cfd software performances in the case of an incompressible air flow through a straight conical diffuser. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 21, S863-S874.
https://doi.org/10.2298/TSCI161020329N

Novković Đ, Burazer JM, Ćoćić A. Comparison of different cfd software performances in the case of an incompressible air flow through a straight conical diffuser. in Thermal Science. 2017;21:S863-S874.
doi:10.2298/TSCI161020329N .

Novković, Đorđe , Burazer, Jela M., Ćoćić, Aleksandar, "Comparison of different cfd software performances in the case of an incompressible air flow through a straight conical diffuser" in Thermal Science, 21 (2017):S863-S874,
https://doi.org/10.2298/TSCI161020329N . .

TY  - CONF
AU  - Ćoćić, Aleksandar
AU  - Brajović, Milan
AU  - Lečić, Milan
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/5483
UR  - https://onlinelibrary.wiley.com/doi/epdf/10.1002/pamm.201610389
AB  - Efficient, and appropriate indoor air environment is important issue in building design. Air flow patterns which are formed in the room are mainly depended on its geometrical parameters. Investigation of flow patterns are performed on a relatively simple geometry of model room, with a small obstacle (partition) in it. There are several interesting flow phenomena which are present in the model room: flow through sudden geometry expansion, stagnation flow with lateral boundaries, flow over the obstacle, etc. Since the air velocities are low, it is assumed that flow is incompressible. Numerical calculations of these patterns have been done using RANS modeling approach. For all calculations an extended version of open-source CFD software OpenFOAM was used. Several turbulence models have been used for RANS approach, with special attention on their performance in capturing unsteady flow phenomena. Comparison of obtained numerical results and available experimental results for mean velocities shown good agreement
C3  - Proceedings in Applied Mathematics and Mechanics (PAMM), Volume16, Issue 1, 2016, pp. 801-802 (Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig 2016
T1  - Numerical Simulation of Air Flow in Model Room
UR  - https://hdl.handle.net/21.15107/rcub_machinery_5483
ER  - 

@conference{
author = "Ćoćić, Aleksandar and Brajović, Milan and Lečić, Milan",
year = "2016",
abstract = "Efficient, and appropriate indoor air environment is important issue in building design. Air flow patterns which are formed in the room are mainly depended on its geometrical parameters. Investigation of flow patterns are performed on a relatively simple geometry of model room, with a small obstacle (partition) in it. There are several interesting flow phenomena which are present in the model room: flow through sudden geometry expansion, stagnation flow with lateral boundaries, flow over the obstacle, etc. Since the air velocities are low, it is assumed that flow is incompressible. Numerical calculations of these patterns have been done using RANS modeling approach. For all calculations an extended version of open-source CFD software OpenFOAM was used. Several turbulence models have been used for RANS approach, with special attention on their performance in capturing unsteady flow phenomena. Comparison of obtained numerical results and available experimental results for mean velocities shown good agreement",
journal = "Proceedings in Applied Mathematics and Mechanics (PAMM), Volume16, Issue 1, 2016, pp. 801-802 (Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig 2016",
title = "Numerical Simulation of Air Flow in Model Room",
url = "https://hdl.handle.net/21.15107/rcub_machinery_5483"
}

Ćoćić, A., Brajović, M.,& Lečić, M.. (2016). Numerical Simulation of Air Flow in Model Room. in Proceedings in Applied Mathematics and Mechanics (PAMM), Volume16, Issue 1, 2016, pp. 801-802 (Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig 2016.
https://hdl.handle.net/21.15107/rcub_machinery_5483

Ćoćić A, Brajović M, Lečić M. Numerical Simulation of Air Flow in Model Room. in Proceedings in Applied Mathematics and Mechanics (PAMM), Volume16, Issue 1, 2016, pp. 801-802 (Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig 2016. 2016;.
https://hdl.handle.net/21.15107/rcub_machinery_5483 .

Ćoćić, Aleksandar, Brajović, Milan, Lečić, Milan, "Numerical Simulation of Air Flow in Model Room" in Proceedings in Applied Mathematics and Mechanics (PAMM), Volume16, Issue 1, 2016, pp. 801-802 (Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig 2016 (2016),
https://hdl.handle.net/21.15107/rcub_machinery_5483 .

TY  - JOUR
AU  - Ćoćić, Aleksandar
AU  - Đorđević, Vladan D.
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2461
AB  - A novel theoretical approach for the calculation of the buoyancy driven air flow in all constitutive parts (entrance to collector, collector, turbines, collector-to-chimney transition section and chimney) of a solar chimney power plant is presented in the paper. It consists in the use of one-dimensional model of flow. The flow in the collector and the chimney is considered as compressible, while the flow in entrance to collector, turbines and collector-to-chimney transition section is treated as incompressible. Differential equations that describe the flow in the collector and in the chimney, together with algebraic equations that describe the flow in other parts of the plant are simultaneously solved. As a result, distribution of basic physical quantities, like velocity, temperature, pressure and density, in the collector and the chimney are obtained. The model is tested on two solar chimney power plants: well known Manzanares plant and Enviromission plant. The obtained results are in good agreement with measured results from Manzanares plant known in literature, together with predicted values of turbine power and turbine pressure drop for Enviromission plant. In addition, dimensional analysis of the model equations is performed and the results for mass flow rate, available turbine power, chimney height, etc. are presented. These results can be used as reliable prediction of the performance of solar chimney power plants.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Solar Energy
T1  - One-dimensional analysis of compressible flow in solar chimney power plants
EP  - 820
SP  - 810
VL  - 135
DO  - 10.1016/j.solener.2016.06.051
ER  - 

@article{
author = "Ćoćić, Aleksandar and Đorđević, Vladan D.",
year = "2016",
abstract = "A novel theoretical approach for the calculation of the buoyancy driven air flow in all constitutive parts (entrance to collector, collector, turbines, collector-to-chimney transition section and chimney) of a solar chimney power plant is presented in the paper. It consists in the use of one-dimensional model of flow. The flow in the collector and the chimney is considered as compressible, while the flow in entrance to collector, turbines and collector-to-chimney transition section is treated as incompressible. Differential equations that describe the flow in the collector and in the chimney, together with algebraic equations that describe the flow in other parts of the plant are simultaneously solved. As a result, distribution of basic physical quantities, like velocity, temperature, pressure and density, in the collector and the chimney are obtained. The model is tested on two solar chimney power plants: well known Manzanares plant and Enviromission plant. The obtained results are in good agreement with measured results from Manzanares plant known in literature, together with predicted values of turbine power and turbine pressure drop for Enviromission plant. In addition, dimensional analysis of the model equations is performed and the results for mass flow rate, available turbine power, chimney height, etc. are presented. These results can be used as reliable prediction of the performance of solar chimney power plants.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Solar Energy",
title = "One-dimensional analysis of compressible flow in solar chimney power plants",
pages = "820-810",
volume = "135",
doi = "10.1016/j.solener.2016.06.051"
}

Ćoćić, A.,& Đorđević, V. D.. (2016). One-dimensional analysis of compressible flow in solar chimney power plants. in Solar Energy
Pergamon-Elsevier Science Ltd, Oxford., 135, 810-820.
https://doi.org/10.1016/j.solener.2016.06.051

Ćoćić A, Đorđević VD. One-dimensional analysis of compressible flow in solar chimney power plants. in Solar Energy. 2016;135:810-820.
doi:10.1016/j.solener.2016.06.051 .

Ćoćić, Aleksandar, Đorđević, Vladan D., "One-dimensional analysis of compressible flow in solar chimney power plants" in Solar Energy, 135 (2016):810-820,
https://doi.org/10.1016/j.solener.2016.06.051 . .

TY  - JOUR
AU  - Lečić, Milan
AU  - Ćoćić, Aleksandar
AU  - Čantrak, Svetislav
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2443
AB  - Measuring spatial correlations of velocity is done by simultaneous measurement of velocity vector in two different measuring points. Usually, the points should be at a very small distance. While performing correlation measurements in turbulent swirling flow in the pipe, it is necessary to have very precise positioning of hot-wire probes, both by angle and distance. In this research, measurements of spatial correlations in such flow field are performed, for two different cases: velocity correlations in two points on different radial distance and in two points on different axial distance, parallel to the pipe axis. For such measurements two original devices for positioning of hot-wire probes are developed. With these devices appropriate angle positioning and radial and axial distance of hot-wire probes are achieved. Cross-correlation diagrams are also given in this article, as an illustration of capabilities of these original devices for hot-wire probes positioning.
PB  - Springer, New York
T2  - Experimental Techniques
T1  - Positioning Devices For Measuring Spatial Velocity Correlations in Turbulent Swirl Flow in the Pipe by Hot-Wire Probes
EP  - 128
IS  - 1
SP  - 121
VL  - 40
DO  - 10.1007/s40799-016-0018-8
ER  - 

@article{
author = "Lečić, Milan and Ćoćić, Aleksandar and Čantrak, Svetislav",
year = "2016",
abstract = "Measuring spatial correlations of velocity is done by simultaneous measurement of velocity vector in two different measuring points. Usually, the points should be at a very small distance. While performing correlation measurements in turbulent swirling flow in the pipe, it is necessary to have very precise positioning of hot-wire probes, both by angle and distance. In this research, measurements of spatial correlations in such flow field are performed, for two different cases: velocity correlations in two points on different radial distance and in two points on different axial distance, parallel to the pipe axis. For such measurements two original devices for positioning of hot-wire probes are developed. With these devices appropriate angle positioning and radial and axial distance of hot-wire probes are achieved. Cross-correlation diagrams are also given in this article, as an illustration of capabilities of these original devices for hot-wire probes positioning.",
publisher = "Springer, New York",
journal = "Experimental Techniques",
title = "Positioning Devices For Measuring Spatial Velocity Correlations in Turbulent Swirl Flow in the Pipe by Hot-Wire Probes",
pages = "128-121",
number = "1",
volume = "40",
doi = "10.1007/s40799-016-0018-8"
}

Lečić, M., Ćoćić, A.,& Čantrak, S.. (2016). Positioning Devices For Measuring Spatial Velocity Correlations in Turbulent Swirl Flow in the Pipe by Hot-Wire Probes. in Experimental Techniques
Springer, New York., 40(1), 121-128.
https://doi.org/10.1007/s40799-016-0018-8

Lečić M, Ćoćić A, Čantrak S. Positioning Devices For Measuring Spatial Velocity Correlations in Turbulent Swirl Flow in the Pipe by Hot-Wire Probes. in Experimental Techniques. 2016;40(1):121-128.
doi:10.1007/s40799-016-0018-8 .

Lečić, Milan, Ćoćić, Aleksandar, Čantrak, Svetislav, "Positioning Devices For Measuring Spatial Velocity Correlations in Turbulent Swirl Flow in the Pipe by Hot-Wire Probes" in Experimental Techniques, 40, no. 1 (2016):121-128,
https://doi.org/10.1007/s40799-016-0018-8 . .