Unsteady Cavity Flows: Oscillatory Flat Box Flows

Abstract

The oscillatory cavity flows reported here are extensions of previously studied steady closed rectangular cavity flows (box flows). The periodic laminar incompressible flows are characterized by three numerical parameters, peak Reynolds number, a reduced frequency (or Stokes number) and the height-to-length ratio of the cavity. Depending on the height-to-length ratio, flow fields are obtained by finite-difference solutions or analytic solutions of the Navier-Stokes equation. The central portion of a flat cavity contains an oscillatory parallel flow. Experimental measurements corroborate the theory. Stokes number dependency and particularly differences from the corresponding steady flow (whose Stokes number is zero) are illustrated.