Evolution of a two-layer fluid for solitary waves propagating over a submarine trench

Abstract The induced density-stratified fluid motion of a solitary wave propagating over a submarine trench was investigated numerically and experimentally. A new laboratory experiment in a two-dimensional wave flume on dense fluid transport and flow fields inside and around the trench was reported using a measurement framework of laser-induced fluorescence (LIF) and particle image velocimetry (PIV) techniques. A 3D Navier–Stokes numerical model was applied to trace the dense fluid transport using the volume of fluid method. Good agreements were obtained between experiments and computed results. The calibrated model was then used to examine the transport processes of the various dense fluids. Particular attention is paid to the evolution of vortices induced by solitary waves. The results indicate that transported height of dense fluid around the windward trench wall decreases when the dense fluid density increases or wave nonlinearity decreases. The dense fluid is allowed to be transported toward the upstream of the trench when a denser fluid or lower wave nonlinearity is considered. The presence of strong vortical structure and vorticity strength was observed as the dense fluid density decreases or wave nonlinearity increases. Quantitative analyses also demonstrate that either density of dense fluid or wave nonlinearity significantly affects the transport process of the dense fluid.