Large Eddy Simulation of Boundary-Layer Flows over Two-Dimensional Hills

Large Eddy Simulations (LES) are performed for turbulent boundary-layer flows over two-dimensional (2D) hills or ridges of two different slopes at Reynolds number equal to 3,120 based on the hill height and the free stream velocity. The surface of the hill is assumed to be aerodynamically smooth. The hill height is considerably smaller than the boundary-layer depth. The hill models used in this study are the same as those used in the RUSHIL wind tunnel experiment carried out by Khurshudyan et al. (United States Environmental Protection Agency Report, EPA-600/4-81-067, 1981) and LES results are compared with the wind tunnel measurements. This study focuses on the overall flow behaviour changes as a function of the hill slope. The results of the mean velocity, the flow separation, and the turbulence quantities are discussed in the paper. It is shown that LES produces overall satisfactory results on the turbulent flow over the 2D hills. Especially for less steep hill, the flow behaviour is well predicted by LES.