Free Oscillatory Flow Across a Plate Orifice in U-Shaped Tube and the Resistance Law

Abstract

The equations governing the motion of viscous fluid across a plate orifice in a U-shaped tube are presented for laminar and turbulent regimes, respectively. Unsteady resistance across a plate orifice is assumed to be composed of two parts. One is proportional to acceleration of fluid and the other to the square of cross-sectional mean velocity. The coefficients in the expression for resistance are determined on the basis of the experiments made here or referring to the previous investigations in steady and unsteady flows. Within the range of the present experiments, the numerical results calculated by assuming that the unsteady resistance across a plate orifice is represented by the well-known quasi-steady relation agree well with the present observations made with video camera.