The effect of stable stratification on turbulence anisotropy in uniformly sheared flow
Direct numerical simulation of uniform shear flow is used to study the anisotropy of fluctuating motion in a stably stratified medium with uniform mean shear. Turbulence is found to be three dimensional over a wide range of gradient Richardson numbers in the two flows investigated here: vertical mean shear (d (U) over bar /dz) and horizontal mean shear (d (U) over bar /dy). The role of the turbulent Froude number in establishing the regime of stratified turbulence observed here is described. The fluctuating velocity gradients are examined. The vertical of streamwise velocity is found to dominate the other components of turbulent dissipation in both horizontal and vertical shear flows. (C) 2003 Elsevier Ltd. All rights reserved.
stratified turbulence geophysical flows direct simulation ocean microstructure