Modeling of dam-break flow with sediment particles over different riverbed forms by coupled level set and volume of fluid-discrete element method

Modeling dam-break flow involving sediment particles presents a significant challenge in hydraulic engineering and multiphase flow due to complex fluid–solid interactions. To address this, an Eulerian–Lagrangian hybrid model for air–water–particle multiphase flow, termed CLSVOF-DEM (coupled level set and volume of fluid–discrete element method) model, is proposed. Within this framework, the CLSVOF method integrates the level set and volume of fluid approaches, using secondary interface reconstruction to accurately capture the air–water interface. Concurrently, the DEM resolves the contact and collision dynamics of sediment particles. By incorporating various fluid–particle interaction forces directly into the governing equations, the coupled CLSVOF-DEM enables robust fluid–solid interactions. The proposed model is validated and subsequently applied to simulate dam-break flows carrying sediment particles over different riverbed forms. This study reveals the hierarchical governing laws of sediment-laden dam-break flows. The sediment material properties are the primary influencing factor: the massive entrainment of highly mobile Polyvinyl Chloride particles consumes considerable flow kinetic energy, slowing the wavefront propagation by approximately 20% and yielding a bed reworking amplitude roughly three times that of natural sand. Bed topography and downstream tailwater constitute the secondary controlling factors that further modulate the flow morphology and bed deformation.