An efficient and generalized solid boundary condition for SPH : Applications to multi-phase flow and fluid-structure interaction

In this paper, we generalize the solid boundary condition where a one-sided Riemann solver is introduced to determine the fluid-solid interaction for weakly compressible smoothed particle hydrodynamics (SPH) presented in Zhang et al. (2017) to model multi-phase flows with large density ratio and multi-phase fluid-structure interaction (FSI) in multi-resolution scenario. Compared with the boundary condition proposed by Adami et al. (2012) where solid is discretized by dummy particles whose physical quantities are extrapolated from surrounding fluid particles, the present method is very simple and efficient as extra extrapolation is avoided by constructing a one-sided Riemann problem for each interacting fluid-solid particle pair. This feature makes its extension to multi-phase flow and FSI straightforward. Furthermore, we adopt a penalty method in multi-resolution discretization to prevent particle penetration in violent multi-phase simulation. A set of examples involving multi-phase flows with high density ratio and complex interface, and multi-phase FSI are studied to demonstrate the accuracy, robustness and versatility of the present method. The validations presented herein and those reported by Zhang et al. (2017) where free-surface flows exhibiting violent events such as impact and breaking are studied indicate that the present method provides a unified approach for addressing the solid, i.e., rigid and flexible, boundary condition in multi-physics SPH applications.(C) 2022 Elsevier Masson SAS. All rights reserved.