Laboratory Studies on the Coupled Oscillations between an Internal Density Interface and a Shear Layer

Abstract

The results from experiments conducted a 2 m high flow compartment at large Reynolds numbers are reported this paper. Flow entered the compartment through an opening at the base on one side of the compartment and exited from an opening at the bottom of the opposite wall of the compartment. A shear layer is formed at the boundary between the incoming flow and the ambient fluid the compartment. The impingement of the shear layer on the opposite wall of the compartment gives rise to periodic vortex formation and highly organized oscillations the shear layer. When a density interface is present inside the compartment, resonance conditions were set up when the oscillations of the internal standing waves were locked in with the shear layer oscillations. Under resonance conditions, internal standing waves with amplitudes of up to 0.1 m were observed. The formation of the internal standing waves is linked to the shear layer oscillations. Resonance conditions result when the shear layer is oscillating close to the natural frequency of the stratified fluid system the compartment. The results of this investigation are applicable for fresh water storage floating bottom-opened tanks the sea, where under resonance conditions, entrainment rates could be significantly increased.