Study of wave-induced mass transport and internal mixing based on a two-liquid VOF model

In this study, the wave-induced mass transport and internal mixing under regular waves propagating in a flume are numerically investigated by a VOF-type (Volume of Fluid) method. A two-phase VOF method based on a multi-phase flow mathematical theory is implemented in a constraint interpolation profile (CIP)-based model to track the free surface and water-water interface simultaneously under Eulerian framework. First, the numerical validation is performed on Stokes drift distribution under regular waves propagating in a flat bottom flume. Good grid convergence and mass conservation are verified. The computed results show favorable agreement with theoretical solution and experimental data. The regular waves propagating over a submerged breakwater are further investigated, focusing on the mass transport and internal mixing in the long term evolution of flow field. The mass transport and water exchange in the vicinity of breakwater are presented qualitatively. A significant water mixing and broken interface are observed even if there is no regular waves breaking. Results indicate that the CIP-based model coupled with the two-phase VOF method can provide a different perspective to study wave-induced mass transport and internal mixing in coastal zone.