Numerical Model of the Turbulent Boundary Layer Beneath Surface Waves and Tides

摘要

A numerical model for horizontally uniform, turbulent, oscillatory flow above a flat rough bed is applied to surface wave-induced and tidal boundary layer flows. The formulation of the problem involves the governing horizontal momentum equations, and closure assumptions which relate the turbulent shear stresses to the mean velocity gradients in the flow. The closure scheme is a standard description of the turbulence field in terms of the turbulent energy equation. This equation, together with various turbulence scaling laws, allows the eddy viscosity to be determined as a function of height and phase angle in the wave cycle. The calculated eddy viscosity distribution is used in the finite difference solution of the governing momentum equations. Results show that the model is useful for the study of rough turbulent oscillatory boundary-layers, and that it predicts quite well the gross features of surface wave-induced and tidal flows.