NUMERICAL SIMULATION OF FLUID FLOW IN THE VICINITY OF AN OSCILLATING CAVITY - PARAMETRIC STUDY

In this paper, numerical solutions of fluid flow in the vicinity an oscillating square cavity are presented. OpenFOAM (v 2.2.2), an open-source, Finite Volume CFD code was used to solve the problem. The oscillating cavity problem was studied with respect to the following parameters: (1) peak Reynolds numbers (based on the cavity size, Red) of 50, 100, 200, and 300, and (2) the ratio of the Stokes layer thickness to the cavity size (3/d) of 0.25, 0.5, and 1. An oscillatory source term was provided to the streamwise momentum equation and the problem was solved with a stationary grid. The resultant fluid velocities were then vectorially corrected for the wall velocity. The patterns and the magnitudes of entrainment and ejection of fluid mass to and from the cavity were studied. Lower Re-d flows were marked by the absence of a secondary recirculation zone inside the cavity in contrast to higher Red flows. Lower Red flows were observed to have fluid contact with the outside shear layer for a larger portion of the oscillatory cycle, and thus, were observed to result in higher effective fluid transport across the cavity. Higher delta/d ratios resulted in decreased peak mass flow across the cavity aperture plane and only over a smaller portion of the cycle time owing to the thickness of the oscillatory boundary layer in relation to the cavity size. As the delta/d was lowered, effective mass flow was observed to increase and over a larger portion of the cycle time.