Time-accurate simulations of a shear layer forced at a single frequency

This paper presents calculations of the forced shear layer studied experimentally by Oster and Wygnanski1 and Weisbrot.2 Two different computational approaches are examined: direct numerical simulation (DNS) and large eddy simulation (LES). The DNS approach solves the full three-dimensional Navier-Stokes equations for a temporally evolving mixing layer, while the LES approach (as applied in this work) solves the two-dimensional Navier-Stokes equations with a subgrid-scale turbulence model. While the comparison between these calculations and experimental data was hampered by a lack of information about the inflow boundary conditions, the calculations are shown to agree qualitatively with several aspects of the experiment. The sensitivity of these calculations to factors such as mesh refinement and Reynolds number is illustrated.