Oscillatory Bottom Boundary Layers

Abstract

A turbulence closure model is applied to the case of an oscillating boundary layer; model calculations compare favorably with data. Wave-induced oscillations can be temporally resolved in a one-dimensional model but not in three-dimensional ocean models, and, indeed, statistical wave models, working in consort with ocean models, can only provide information on expected wave periods and amplitudes. Therefore, in this paper, a way has been found to parameterize the effects of bottom flow oscillations; it entails augmenting the turbulence shear production as a function of amplitude and period of the oscillation, the bottom shear stress of the mean current flow, and the angle between the directions of the oscillations and the mean flow. The more conventional method of solving for an apparent wall roughness is also investigated in an appendix.