Instability at an Interface Between Oil and Flowing Water

Abstract

A linear, inviscid stability analysis is applied to the case of a relatively thin layer of stationary oil over a semi-infinite layer of water flowing at a constant velocity. Predictions of the velocity at which the interface becomes unstable and the effect of the oil depth on this velocity agree qualitatively with observations. Results can be applied to the problem of containing oil with mechanical booms. The model predicts initiation of oil loss by droplet separation from beneath the slick at low current velocities, for example, 0.39 to 0.53 fps for No. 2 diesel fuel depending on slick thickness. For practical purposes, earlier experiments have shown that this initial small oil loss by droplet entrainment can be tolerated up to a higher velocity of about 1.0 fps where substantial oil loss occurs.