Research in Engineering and Aviation

Unsteady Gaseous Diffusion Associated With a Fully Cavitating Oscillating Flat Plate Hydrofoil

June 1991

Author(s): Ravindra, K., and Parkin, B.R.

Presented at the 22nd American Towing Tank Conference, St. Johns, Canada, August 1989.  Also published in the Journal of Fluids Engingeering, 113(2), pp. 290-294, June 1991.  DOI: 10.1115/1.2909494.


This paper gives an analysis of convective gaseous diffusion into a full cavity behind an oscillating flat-plate hydrofoil in a turbulent flow. The unsteady diffusion theory accounts for fluctuations of cavity gas pressure and length which are assumed to be harmonic oscillations but are not necessarily in phase with the hydrofoil motion. A diffusive lag function is found which, for a given reduced frequency, determines the instantaneous diffusion rate as a product of the lag function and the quasisteady mass diffusion. The present results can be used to study the rate of gas entrainment from the cavity into the wake behind the oscillating cavity.