Instabilities of Decelerating Flow

Abstract

This paper numerically investigates the instability characteristics of decelerating flows. The flow dynamics and temporal evolution of coherent structures in a diverging section with mild spatial pressure gradient are analyzed using numerical experiments with Incompact3d code. The unsteady nature of flow and adverse pressure gradient is the reason for inflectional velocity profiles, results into boundary layer separation and instability with reverse flow and later on it leads to vortex formation. Vortex formation time is found by vortex Reynold's number. Time of first vortex formation, non-dimensional vortex formation times with Reynold's number etc. are validated with an experimental results.