Effects of the size and friction coefficient of particles on a liquid-gas-particle mixture flow in dam break

The present study numerically investigated the liquid-gas-particles mixture flow during dam break using the computational fluid dynamics (CFD) and discrete element method (DEM). The adopted numerical methods were validated through comparison with previous researches of computation and experiments. The focus is on the effect of the particle friction coefficient (PFC) and the ratio of a particle size to a baseline size (PS) on behavior of the particles and the free surface. The PFC ranges from 0.1 to 0.9 and the PS varies from 50% to 100%. The liquid front position and the formation of the free-surface are almost independent of PFC and PS. In contrast, the particle front position strongly depends on PFC and PS. The particle front velocity showed two pattern according to time. First pattern is the increasing and then saturated behavior. Second pattern has increasing and decreasing behavior. These two patterns are mainly governed by the PFC. Generally, a smaller PFC and a larger PFC lead to first and second patterns, respectively. We could classify all cases of PFC and PS by the arrival time of particles into earlier and later arrivals than liquid front.