Large-Eddy Simulations of Stratified Flows over a Ridge Using a Lattice Boltzmann Model

A three-dimensional multiple-relaxation-time lattice Boltzmann model (MRTLBM) has been developed at US Army Research Laboratory for modeling of the complex turbulent flows in the atmospheric boundary layer of steep terrains and urbans. In this validation process, we used the MRTLBM for the simulations of stratified flows over a bell-shaped ridge to compare some laboratory results. The effects of different atmospheric thermal stratification conditions on the lee-side flow structures such as waves, rotors, and hydraulic jump were simulated. The results compared favorably with the laboratory results and with some traditional meteorological model results. The test results have also shown that the impact of the turbulent boundary layer on the lee-side of the flows is particularly important in dissipation of the flow structures.