Wind Around Tall Building: A Comparison Between RANS and LES

With the expansion of city, more and more tall buildings arise. It is very important to understand the wind field around buildings for creating safe and comfortable wind environment. At present, three kinds of methods can be used to obtain the wind field information around tall buildings. They are wind tunnel experiment, wind field measurement, and numerical simulation. Numerical simulation is the cheapest way, in which Reynolds averaged Navier-Stokes equations and large eddy simulation approaches are commonly used to simulate turbulent flow. To ensure the accuracy and reliability of the two approaches, the solution validation studies are needed. In this paper, Shear Stress Transport (SST) k - omega model has been used in solving Reynolds averaged Navier-Stokes equations (RANS) and kinetic-energy transport subgrid model has been employed in large eddy simulation (LES) in the simulation of the flow field around a square column. Comparing the numerical results with experimental data, the characteristics of the two models are revealed and their reliability is analyzed. The results show that both kinetic-energy transport model in LES and SST k - omega model in RANS can be used to simulate the field around building but the results are different. With kinetic-energy transport model in LES, the vortex generation and a group of high vertex zones are observed.