Two-dimensional CFD–DEM simulation of vertical shock wave-induced dust lifting processes

Abstract

This paper conducts a numerical study of particle dispersion by vertical shock waves using a combination of computational fluid dynamics and the discrete element method (DEM). The Magnus force is important for particle dispersion, and the DEM approach can consider the rotation of individual particles and provide a detailed analysis of particle–particle and particle–wall interactions. Simulations are conducted and the results are compared with those of previous experiments, showing that the models can capture the particle dispersion process and shock wave geometry inside the mixed gas–particle region. During the particle dispersion process, the contact force due to the particle–particle interactions causes the particles to move upward after the shock wave passes and then decreases rapidly due to the low collision frequency in the particle cloud. The Magnus force is initially lower and has little effect until the contact force decreases, when it becomes dominant and maintains the particles’ upward movement. It is mainly driven by the gas rotation above the dust layer, and the effect of particle rotation is relatively small in comparison. The gas velocity gradient above the dust layer in the particle dispersion region is caused by gas–particle interactions. The particle dispersion region becomes wider and thinner over time, meaning that the gas velocity gradient above the dust layer becomes small and hence that the Magnus force (which is driven by the gas rotation) also becomes small. In contrast, the downward drag force remains constant during the vertical motion because it is primarily affected by the velocity difference between the particles and the gas. This means that the drag and Magnus forces eventually balance, and the particles stop rising.