A robust low-dissipation Riemann-SPH solver with a novel hybrid boundary treatment method for FSI problems

Smoothed Particle Hydrodynamics (SPH) method is currently widely used to simulate fluid-structure interaction (FSI) problems, however, challenges such like the particle penetration, fluid tensile instability (TI) problems still arise near the fluid-structure interfaces using the SPH method. In this paper, a highly robust SPH solution method without any empirical parameters and numerical noise was proposed. The coupled normal flux and fixed dummy particle boundary treatment method was chosen to impose the boundary conditions, and an enhanced Riemann SPH solver was introduced to smooth transitions of field variables near the interface. Robustness and accuracy of the proposed method were validated through three typical FSI cases, including water entry of the 2D cylinder, sinking of an eccentric rigid box and water entry of a wedge. Results indicate a high degree of consistency between the present results and reference results. Given that only a single layer of particles needs to be set when using this SPH solution method to discretize structures, the present SPH solution method is suitable for simulating FSI problems with sharp corners or complex geometries and shows promising applications.