Numerical modelling of velocity profile parameters of the atmospheric boundary layer simulated in wind tunnels

Abstract

Experimental and numerical modeling and simulations of the wind influence within the atmospheric boundary layer are essential tools in optimum building structural design. Each of these methods, however, has both advantages and disadvantages. In experimental investigations performed in wind tunnels, reliable results can be obtained, but detailed information of the wind profile parameters, such as the surface roughness length z 0 or the friction velocity u∗, are difficult to determine. Numerical simulations, on other hand, easily yield any information of the wind velocity profile. However, the reliability of numerical results strongly depends on the established and adopted computational model. This paper presents the computational fluid dynamics (CFD) analysis of the atmospheric boundary layer simulated in subsonic wind tunnels using appropriate types of obstacles, based on the SST k-ω turbulence model with optimized unstructured mesh and optimum selection of relevant physical model parameters, performed in Ansys Fluent software. Results have been compared with the measurements from the Assiut University wind tunnel with maximum velocity of 4 m/s, and from subsonic wind tunnel at Belgrade University, with maximum air velocity of 45 m/s. Detailed comparisons for velocity distributions with these experimental results have shown very good conformity. Also, the three-parameter fitting methods were successfully established to define surface roughness length z 0 and the friction velocity u∗. Obtained results have shown that the established numerical model is able to substitute a remarkable number of expensive wind tunnel tests hours within the operational investigations of wind influence on the building structures.