Unsteady Fluid Dynamics in a Semi-Closed Cavity

Results are presented for unsteady, time-true simulations of a shear driven cavity started impulsively from rest. The cavity is partially occluded by slits on its upper side, thereby forming a Helmholtz resonator type of geometry. Simulations with Reynolds-averaged Navier-Stokes solvers at the laminar Reynolds number Re = 3,000, for a spanwise aspect-ratio equal to 3, showed that the flow is unsteady and a-periodic over a normalised time of one hundred units. Taylor-Go¨rtler spanwise vortices appear early in the simulation (flow time 3 or 4 units); these vortices have a relatively short time span, and completely disappear at a flow time equal to 90. This study also reports about the findings on the secondary eddies (upstream and wall vortices), on the vortex filaments that are drawn from the cavity floor, and on the mass transport properties of the flow.