Numerical simulation of rotor-induced dust cloud based on CG-DEM method

In desert environments, the dust cloud induced by rotor downwash (the “brownout” phenomenon) consists of an enormous number of sand and dust particles, which causes a sharp drop in visibility around the aircraft, posing a serious flight safety hazard. In existing relevant numerical simulation studies, the method of tracking real particles incurs extremely high computational costs, while simulations with reduced particle counts can only achieve qualitative analysis, failing to meet the requirements of quantitative prediction. Based on the Coarse-Grained Discrete Element Method (CG-DEM), four-way coupling is adopted to account for inter-particle collisions and the feedback effect of particles on the flow field. By tracking Coarse-Grained (CG) particles, simulation results that quantitatively agree with the actual development of rotor-induced dust cloud can be obtained. To consider the influence of turbulence on particle transport in rotor-induced dust cloud, a particle drag force model incorporating turbulent effect is employed. The results show that the CG-DEM can effectively realize the quantitative simulation of rotor-induced dust cloud. For the case in this study, the use of the drag force model considering turbulent effect improves the prediction accuracy. In the steady state, the number of airborne particles increases by approximately 27% compared with the traditional drag model, and the error between the predicted sand transport rate and the experimental measurement is less than 5%.