Numerical prediction of local scour around marine structures using an Eulerian three-phase model

Accurately predicting local scour around marine structures is vital for ensuring foundation stability and guiding effective protection measures. This study uses an Eulerian three-phase computational model that concurrently resolves sediment, water and air phases to simulate scour around a cofferdam under steady current forcing with an explicitly resolved free surface. The model incorporates advanced granular physics through a μ(I) rheology, providing a realistic description of dense sediment behaviour and internal stresses. Numerical results are validated against cofferdam flume experiments, showing reasonable agreement in the time evolution of the maximum scour depth and in the development of the bed profiles. The simulations reproduce key scour features, including the formation of a localised scour hole and associated downstream deposition. The results demonstrate that three-phase, physics-based computational fluid dynamics can predict cofferdam scour evolution and support improved scour risk assessment and mitigation design in offshore and coastal engineering.