Vortex generation and flow pattern development after a solitary wave passing over a bottom cavity

Several vortices are generated immediately inside the cavity for a short duration when a solitary wave passes over a bottom cavity in shallow water. Afterward, the primary vortex grows gradually in size and then is transported outward to breed another counter-rotating vortex to form a jet in the tranquil environment. In this study, a two-dimensional streamfunction–vorticity model was treated in a transient grid to conform the free surface and formulated by the Finite Analytic (FA) discretization to seek a time-accurate numerical solution. We used an overset grid to refine the small region around the cavity to improve the solution accuracy and obtain computational efficiency in the analysis. The model was first validated for a quasi-steady boundary-layer flow, induced by a solitary wave passing over a flat bottom, through the comparison of velocity profiles with Liu et al. [J Fluid Mech 2007;574:449–63]. Then, the evolved vortical flow for the cavity problem was investigated under the effects of various sizes of a cavity and various amplitudes of the incident solitary wave. These simulated results showed consistent agreement in the evolved vortex patterns with the visualization experiment in laboratory.