Simulation study of the sediment gravity flow using solid fluid coupling method

We calculate a grains flow along a slope under the water as an example of the sediment gravity flow. The flowing grains shape the bump at the head of the flow. This is called 'flow head'. We confirmed the following some features in this simulation. First, the flow velocity of some grains inside the flow head is faster than that at the tip of the flow head. This is because the resistivity from the fluid at the tip of the flow head is higher than that inside the flow head. Second, a few slip surfaces appear inside the flow. The angles of these slip surfaces are the angle of slope +1-3 ° inside the body part (this is the part except the flow head). On the contrary, the angle inside the flow head is much higher than that inside the body part. This is because some lower particles at the flow head are willing to settle down to the slope.The last, the velocity of the flow head is almost constant on the slope, but it decreases to a velocity after the grains reach the flat part. This second velocity lasts until the head part becomes small well. After then, the head velocity decreases linearly and the flow stops. These trends are almost same under the different slope angle and the grain size distribution in our simulation. The feature of the sediment gravity flow varies according to many factors such as grain distribution, grain density, slope angle, flow viscosity and so on. As our results are just performed under the quite limited condition, we need further simulations with more parameters changing. We concluded that the coupling simulation of LBM and DEM can reveal some features of the gravity sediment flow. The further simulations with more parameters changing, however, are required, as our results are just performed under the quite limited condition,