A Bottom Boundary Layer-resolving Three-Dimensional Tidal Model: A Sensitivity Study of Eddy Viscosity Formulation

Abstract

Abstract A three-dimensional hydrodynamic model of the Irish Sea that resolves the bottom boundary layer, including the logarithmic layer, is developed. A finite-difference grid is employed in the horizontal, with the current profile through the vertical being determined from an expansion of functions satisfying a no-slip bottom boundary condition. By this means a continuous current profile in the vertical, resolving the bottom boundary layer, is determined. The sensitivity of computed tidal current profiles and tidal elevations to a range of eddy viscosity parameterizations and profiles is examined, with a view to determining appropriate formulations to use in three-dimensional hydrodynamic models with no-slip bottom boundary conditions. The importance of near-bed eddy viscosity in determining the dissipation of tidal energy (in a model with a no-slip condition) and hence tidal elevations, is considered together with its influence upon current profiles. Computed and observed tidal elevations and currents...