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Disruption of the bottom log layer in large-eddy simulations of full-depth Langmuir circulation

Published online by Cambridge University Press:  27 March 2012

A. E. Tejada-Martínez*
Affiliation:
Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620, USA
C. E. Grosch
Affiliation:
Center for Coastal Physical Oceanography and Ocean, Earth and Atmoshpheric Science, Old Dominion University, Norfolk, VA 23509, USA
N. Sinha
Affiliation:
Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620, USA
C. Akan
Affiliation:
Civil and Environmental Engineering, University of South Florida, Tampa, FL 33620, USA
G. Martinat
Affiliation:
Center for Coastal Physical Oceanography and Ocean, Earth and Atmoshpheric Science, Old Dominion University, Norfolk, VA 23509, USA
*
Email address for correspondence: aetejada@usf.edu

Abstract

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.

Type
Papers
Copyright
Copyright © Cambridge University Press 2012

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