Journal of Fluid Mechanics

Table of Contents - Volume 699 - 2012  

Papers

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

A. E. Tejada-Martíneza1 c1, C. E. Groscha2, N. Sinhaa1, C. Akana1 and G. Martinata2

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

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 $90\lt { x}_{3}^{+ } \lt 200$. 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)

Key Words:

  • boundary layer structure;
  • ocean processes;
  • turbulent mixing

Correspondence:

c1 Email address for correspondence: aetejada@usf.edu

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