Numerical simulation of interactions between free surface and rigid body using a robust SPH method

•A SPH algorithm is described to simulate fluid–solid interactions with reduced pressure noise.•Calculation of forces and torques on rigid body is improved for higher accuracy.•The dummy particle boundary is improved in both the pressure extrapolation and velocity extension.•3-D cylinder water entry experiment is conducted to validate the SPH scheme.

A robust weakly compressible SPH method is applied to simulate violent interactions between free surface and rigid body. Artificial density and viscosity diffusion are applied to stabilize the pressure field. The calculation of forces and torques on rigid body is improved for higher accuracy. Improved dummy particle technique for stationary and moving boundary is analyzed and applied in both free-slip and no-slip condition. For the velocity divergence approximation near the dummy particle boundary, it is proved that substituting the velocity of the rigid body directly into the divergence operator is acceptable and reasonable. For the viscous stress calculation, the dummy particle velocity extension manners in both free-slip and no-slip boundary condition are given in higher accuracy. The present solid boundary technique is convenient for both two-dimensional (2-D) and three-dimensional (3-D) models. Stability and accuracy of the present SPH scheme are tested by four 2-D cases and two 3-D cases, and the results agree well with both experimental data and other numerical results. The present SPH scheme is potential for some ocean engineering applications with violent fluid–solid interactions.