Wave Boundary Layer
Interactions between surface waves and high-relief bottom roughness were investigated using LES of oscillatory flow over idealized topography composed of an infinite array of hemispheres. Simulation results were analyzed using a spatially- and phase-averaged momentum budget to provide insight into how flow-topography interactions affect wave-driven oscillating flows. Flow dynamics strongly depended on Keulegan-Carpenter number. At low KC the inertial force dominated flow dynamics, form drag was small, and Reynolds and dispersive stresses were negligible. At higher KC, strong flow separation occurred, both drag and inertial forces were important. The dispersive stress was the main mechanism for vertical momentum transfer.