Oscillatory flow around discs and through orifices

Examples of unsteady, axisymmetric, separated flows are modeled, including unbounded oscillatory flow around a disk and bounded oscillatory flow through a sharp-edged orifice. Calculations are made, assuming that the flow is inviscid and that the shed vortex sheets can be represented by sequences of discrete vortex rings. The solid bodies, i.e., the disk or the orifice and bounding tube, are also represented by a distribution of bound discrete vortex rings whose strenghts are chosen to satisfy the Neumann or zero normal velocity boundary condition. The results of flow visualization experiments and, for the orifice, pressure drop measurements are reported. In general, the gross properties of the flows are predicted accurately.