A lattice Boltzmann-Saltation model and its simulation of aeolian saltation at porous fences

Abstract

This paper introduces a 2D lattice Boltzmann-Saltation (LBM-Saltation) model for numerical simulation of velocity profiles of windblown sand particles. The model is based on the LBM equations for transient, incompressible viscous flow. We first introduced a lattice Boltzmann subgrid model, which was used to predict the turbulent wind field. Two-way coupling was then used to describe the interaction between wind and the saltating sand particles. The correctness of the model was verified by comparing the simulated results of several important variables of wind-sand flow with that of experiment over a flat bed surface. To show the feasibility of this model with complex boundary conditions, we used it to simulate the wind-sand flow at porous wind fences and mainly discussed the particle velocity profiles. Single porous wind fence case was computed first and compared with the measurement. Two tandem porous wind fences cases were simulated next. Different distance and porosity of the fences were considered to quantitatively investigate the variation of the shelter effect. The simulated results achieved additional conclusions: The wind speed and the velocity of sand particles are obviously weakened because of the fence; reduction of the particle velocity by porous fence varies with the fence distance and porosity; the larger the distance or the porosity (significantly larger than the 0.3), the worse the shelter effect, and the weaker the reduction of particle velocity.