Impulsive Waves Generated by the Collapse of a Submerged Granular Column: A Three-Phase Flow Simulation with an Emphasis on the Effects of Initial Packing Condition

Submarine landslides are one of the major causes of tsunamis but less understood due to complicated dynamics involved and the lack of observational data. In this study, the collapse of a submerged granular column is used as an idealized submarine landslide model. A three-phase (solid-liquid-gas) continuum model is used to study the effect of the column's initial packing on the collapse process and the resultant waves. Numerical simulations reveal that the initial packing can have significant effect on the duration of the collapse process and the characteristics of the resultant waves. Pore pressure, velocity field of the fluid phase, the volume of the sliding granular mass, and the sliding velocity are calculated and used to understand the effects of initial packing condition. Our results show that it is important to consider the initial packing effects in numerical simulations of submarine landslides and the resultant waves. Our result also show that the large vortex generated by the moving front of the granular flow can affect the form of the waves generated by the landslide.