Modeling the influence of wave-enhanced turbulence in a shallow tide- And wind-driven water column

Abstract

The ability of one-dimensional hydrodynamic models to reproduce dissipation of turbulent kinetic energy and velocity profiles for conditions of whitecapping waves in a shallow water, tide- and wind-forced environment was assessed. The models were forced with the conditions experienced during a month-long field experiment in a shallow estuarine embayment, and the results were compared with the observed dissipation and mean velocity profiles. Three turbulence models were assessed: the k-ω model and two k-l models, with different prescribed bilinear relationships for the turbulent length scale, l. The k-ω turbulence model was found to best replicate the measured decay of dissipation with depth with a surface roughness length, z0s = 1.3HS, and wave energy parameter, α = 60. The k-l model achieved equally as good reproduction of the observations as the k-ω model when the proportionality constant in the prescribed linear length scale relationship for the upper half of the water column was modified from the traditionally employed von Karman's constant, K = 0.4, to 0.25. The model results show that the whitecapping waves often supplied the dominant source of turbulent kinetic energy over the majority of the water column in the shallow, tide- and wind-forced system. Copyright 2008 by the American Geophysical Union.