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Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

DIRECT NUMERICAL SIMULATIONS OF TURBULENT FLOW OVER MOVING SINUSOIDAL BOUNDARIES

Peter P. Sullivan
National Center for Atmospheric Research Boulder (CO), USA

James C. McWilliams
National Center for Atmospheric Research, Boulder, CO

Chin-Hoh Moeng
National Center for Atmospheric Research, Boulder, CO

Abstract

Turbulent flow over idealized water waves is investigated using direct numerical simulations at a bulk Reynolds number Re = 8000 over non-evolving water waves with varying waveslope αk and wave age c/u* . The results show that waves significantly influence the mean flow, vertical momentum fluxes, velocity variances, pressure, and form stress (drag). Compared to a stationary wave, slow (fast) moving waves increase (decrease) the form stress. A region of closed streamlines (or cat's-eye pattern) centered about the critical layer height was observed at low to moderate values of c/u* and was found to be dynamically important in determining the mean flow, turbulent fluxes, and surface form stress.