A WCSPH-MSDEM model for combined rolling and sliding motions of complex-shaped blocks in an unsteady flow

Abstract

A coupled Weakly-Compressible Smoothed Particle Hydrodynamics (WCSPH) and Multi-Sphere Discrete Element Method (MSDEM) numerical model is employed to investigate the interaction between a discrete, complex-shaped block and a solid boundary in unsteady flows. The study focuses on enhancing the original MSDEM by developing a virtual surface algorithm that assigns a surface normal vector and a virtual surface to each boundary sphere, thereby allowing for a more accurate representation of the true boundary geometry. This approach ensures a precise description of normal contact between the block and the boundary while preventing the embedding phenomenon during the block’s sliding motion. To accurately simulate frictional behavior, both static friction theory and Coulomb’s law of kinetic friction are incorporated. A series of test cases are conducted to validate the modified MSDEM, with further validation of the coupled WCSPH-MSDEM model against experimental data concerning with the sliding motion of a hollow square under solitary waves. Finally, a numerical case study on combined rolling, sliding, and collision of a hollow square on a slope under plunging waves is presented, highlighting the stability and robustness of the proposed model.