Large eddy simulation of atmospheric boundary flow over two two-dimensional hills

Understanding turbulent flow over two-dimensional hills is important for microscale meteorology research and application. Most of the existing work focuses on only one hill, and few consider two hills. This Letter adopts the large eddy simulation method to investigate flow and turbulent structures over two two-dimensional hills. In the presence of the second hill, the low-pressure region behind the first hill is extended and recirculated flow in the valley is enhanced. Larger negative velocity forms near the surface before the second hill. Behind the second hill, a reattachment point is closer to the foot of the hill; recirculation is weakened and turbulent kinetic energy is significantly decreased, but the spanwise turbulent fluctuation near the surface is increased. Published under an exclusive license by AIP Publishing.