Vortex shedding from a submerged rectangular obstacle attacked by a solitary wave

Abstract

This study investigates the two-dimensional flow of a solitary wave that passes over a submerged rectangular obstacle using a Lagrangian-type numerical method. The main purpose is to investigate vortex generation and evolution caused by the obstacle. The numerical method is based on the combination of vortex methods and boundary integral methods using the Helmholtz decomposition. The simulated flow pattern is compared with the experimental measurements in detail, and the overall agreement is reasonably good. A series of simulations were performed with various wave heights to study the effect of wave height on vortex generation and evolution. The relation between the vorticity field and the drag experienced by the obstacle is also discussed. In the presented cases, the effects of the generated vortices are preserved over a long period, and may cause local scouring of the foundation at the lee side of the obstacle. The deformation of the solitary wave is not much affected by the presence of the vortices, but the drag is significantly affected by the vorticity field. An almost linear relationship between the Reynolds number and the maximum magnitude of the drag (positive and negative) is observed.