Three-dimensional numerical simulation of wave-induced scour around a pile on a sloping beach

Abstract

A fully-coupled (hydrodynamic and morphologic) numerical model based on the open-source CFD package OpenFOAM is presented and utilized to simulate breaking wave induced scour around a pile on a sloping beach. The hydrodynamic model is based on RANS equations together with k-ω turbulence closure and volume of fluid method for capturing the free surface. These are then coupled with both bed load and suspended load transport descriptions, which drive resultant morphology of the bed. The model is validated against large-scale laboratory experiments involving interaction of breaking solitary waves with a pile and induced flow and scour. The flow features and hydrodynamic characteristics around the pile are described in detail, and the scouring mechanism at different locations of the pile is thoroughly analyzed. The simulated flow field confirms the formation of horseshoe vortex in front of the pile induced by plunging breaking wave. The temporal variation of scour depth at the side of the pile is satisfactorily simulated while those at the offshore and onshore are under-predicted. The scour depth at the side of the pile increases twice during run-up and draw-down. The scour at the onshore location of the pile starts to increase rapidly at the end of wave drawdown.