Numerical Study Of Incompressible Fluid Flow In A Vertically Dropping Pool With And Without End Sill

Abstract

The study involves numerical analysis of flow field for three different flow regimes taking place in a vertically dropping pool. In general, a vertically dropping flow generates a skimming flow regime with one recirculation zone along with a developing shear layer. The presence of an obstacle (end sill) results in the formation of another recirculation zone downstream of the impinging jet. Based on the nature of these zones, the flow is categorized as napped, periodically oscillatory and skimming. The type of flow regime depends on the flow parameters like velocity and depth of flow which are controlled by Froude number. Unlike a skimming flow, shear layer in a napped flow is under the influence of two opposite circulations which affect the velocity profile in this region. The recirculation zones in case of an oscillatory flow keep changing periodically. Hence, the velocity profiles would be similar to those of napped and skimming patterns alternatively in one period. The effect of end sill and flow parameters on flow regimes has been studied. Velocity profiles within the shear layer and recirculation zones are examined and found to be in agreement with experimental findings reported in literature.The governing equations for the flow are solved by a finite volume scheme with a two-step projection method on a fixed computational domain. The free surface is tracked using a coupled level set and volume-of-fluid method with a piecewise linear interface construction scheme.