Simulation of wind gust structure in the atmospheric boundary layer with Lattice Boltzmann Method

Cold fronts occur in northern East Asia during winter and spring. After cold frontal passage, airflow is downward and accompanying strong winds fluctuate significantly; this is termed wind gusts. Analysis of observation data shows that wind gust structure has coherent characteristics. This is important for entrainment of spring dust storms into the upper boundary layer, where they are transported great distances. The Lattice Boltzmann Method (LBM) is a computational fluid technique based on the Boltzmann transport equation. The LBM has been used to study complex motion such as turbulence, because it describes motion at the micro level. In this paper, Large eddy simulation is introduced in the LBM, enabling simulation of turbulent flow in the atmospheric boundary layer. The formation and development of wind gusts are simulated, and a coherent structure with a combination of wave and vortex is obtained. This explains the mechanism of soil erosion and sand entrainment by the coherent structure of wind gusts.