A coupled metaball discrete element material point method for fluid-particle interactions with free surface flows and irregular shape particles

Interactions between fluids and particles are common in both natural and industrial fields. However, modeling these intricate interactions presents considerable challenges, especially when dealing with free surface flows and irregularly shaped particles. In this work, a hybrid approach that combines the Material Point Method (MPM) and the Metaball Discrete Element Method (MDEM) is proposed to address this challenge. The advantages of the MPM in handling free surface flows and the capability of the MDEM in modeling the mechanical behaviors of irregular shape particles are integrated. To calculate normal and tangential interaction forces, a DEM-based coupling strategy is employed. Furthermore, a novel collision scheme is introduced to accurately determine collision characteristics between MPM points and MDEM particles, particularly when their diameters differ significantly. To demonstrate the effectiveness of the proposed coupling approach, three classical benchmarks are conducted. The numerical results are compared with the experimental data, demonstrating the coupling model's capability to accurately capture complex fluid-particle interactions. Finally, an example involving a landslide-induced wave is simulated to illustrate the potential applications of the proposed method.