Dam-break flows over erodible beds represent a complex fluid–solid interaction problem characterized by extreme turbulence and rapid morphological changes. This study investigates the dynamics of such flows over inclined granular beds by integrating an advanced Moving Particle Semi-implicit (MPS) method. To accurately resolve the transition between static and kinetic granular regimes, I introduce a state-dependent tangential friction model that explicitly distinguishes between sticking and sliding conditions based on local force balance. Furthermore, the momentum exchange between the fluid and solid phases is rigorously modeled using the porosity-dependent drag formulation. The numerical results demonstrate a distinct regime shift in energy dissipation: while low-inclination beds (0–4%) promote distributed sediment transport, steep-inclination beds (8–12%) trigger a localized “Shielding Effect”. In this regime, the surge’s horizontal kinetic energy is rapidly converted into vertical potential energy and frictional work, forming a deep sacrificial scour hole that acts as a topographical energy sink. This mechanism effectively mitigates the destructive potential of the surge in downstream areas. The proposed method provides a robust tool for predicting morphological feedback and designing topographical countermeasures for disaster mitigation in hydraulic and coastal environments.
Kyung Sung Kim (Thu,) studied this question.