Pseudo-fluid Particles for Fluid-rigid Body Coupling in SPH

Abstract

The present study introduces the concept of pseudo-fluid particles for modeling fluid-rigid body interaction in Smoothed Particle Hydrodynamics (SPH). Such particles obey rigid body dynamics in a fully coupled framework with fluid pressure forces acting as external excitations for the object. The proposed algorithm allows treating the actual rigid body as a hollow shape composed of few layers of pseudo-fluid particles, the mass of which is introduced as an input data, rather than computed by summing up the contribution from individual particles. This decreases the computational cost by reducing the number of particles to be involved in the simulation. A modification is introduced in the discretized mass conservation equation which improves the computational accuracy when the flow is mostly dominated by hydrostatic pressure distribution. To highlight the role of this modification, a buoyant floating object is shown to properly maintain its initial equilibrium over relatively long simulation time. The efficiency of proposed model is then evaluated by reproducing the well-known Scott Russell’s wave generator in three cases, followed by the wedge water entry problem. Comparisons with available experimental measurements demonstrate reasonable agreement in predicting different aspects of generated flow field.