Large-eddy simulation of turbulent boundary layer flow over multiple hills

Atmospheric boundary layer (ABL) flow over multiple-hill terrain is studied numerically. The spectral vanishing viscosity (SVV) method is employed for implicit large eddy simulation (ILES). ABL flow over one hill, double hills, and three hills are presented in detail. The instantaneous three-dimensional vortex structures, mean velocity, and turbulence intensity in mainstream and vertical directions around the hills are investigated to reveal the main properties of this turbulent flow. During the flow evolution downstream, the Kelvin-Helmholtz vortex, braid vortex, and hairpin vortex are observed sequentially. The turbulence intensity is enhanced around crests and reduced in the recirculation zones. The present results are helpful for understanding the impact of topography on the turbulent flow. The findings can be useful in various fields, such as wind energy, air pollution, and weather forecasting.