a1 Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620, USA
a2 Center for Coastal Physical Oceanography and Ocean, Earth and Atmoshpheric Science, Old Dominion University, Norfolk, VA 23509, USA
We report on disruption of the log layer in the resolved bottom boundary layer in large-eddy simulations (LES) of full-depth Langmuir circulation (LC) in a wind-driven shear current in neutrally-stratified shallow water. LC consists of parallel counter-rotating vortices that are aligned roughly in the direction of the wind and are generated by the interaction of the wind-driven shear with the Stokes drift velocity induced by surface gravity waves. The disruption is analysed in terms of mean velocity, budgets of turbulent kinetic energy (TKE) and budgets of TKE components. For example, in terms of mean velocity, the mixing due to LC induces a large wake region eroding the classical log-law profile within the range . The dependence of this disruption on wind and wave forcing conditions is investigated. Results indicate that the amount of disruption is primarily determined by the wavelength of the surface waves generating LC. These results have important implications for turbulence parameterizations for Reynolds-averaged Navier–Stokes simulations of the coastal ocean.
(Received July 19 2011)
(Reviewed January 02 2012)
(Accepted February 09 2012)
(Online publication March 27 2012)