Smoothed Particle Hydrodynamics Simulations of Cavity Generation/Collapse and Resulting Wave Heights From the Impact of Tsunamigenic, Subaerial Landslides

The impact of a deformable object with a body of water, such as with tsunamigenic, subaerial landslides, can lead to a complex near-field wave structure that can involve the generation of a substantial air cavity. The structure of the initiation and collapse of this cavity depends on the impact angle, velocity and geometry of the impacting landslide and is a likely source of the significant variations in the efficiency of energy transfer from landslide motion to the resulting wave energy. The severe deformation of the interfaces between landslide material, water and air can be problematic to simulate with many numerical methods. Eulerian grid- based methods are disadvantaged by their inherent difficulty tracking interfaces between phases. While Lagrangian grid-based methods naturally track material interfaces, they generally have difficulties with the significant deformation during the impact. Combination grid-based methods, such as the Arbitrary Lagrangian-Eulerian method, have been constructed to both allow for large deformation and track Lagrangian motion, and have been applied to modeling tsunamigenic landslides. In contrast to these grid- based methods, Lagrangian particle methods, such as Smoothed Particle Hydrodynamics (SPH), do not rely on an underlying mesh and both allow for large deformations and the tracking of Lagrangian motion. We have implemented an SPH model to study this impact process, cavity generation, and energy transfer. We treat the landslide as an incompressible, viscous fluid and the water as an incompressible, inviscid fluid. We present numerical experiments showing the dependence of the predicted solitary wave motion on the velocity and impact angle of the landslide, as well as the geometry of the impacting front of the landslide.