Shear flow induced interface instability

A system of two stratified layers at a free surface, consisting of distille d water above a layer of salty separated by an interface, is studied under laboratory conditions involving uniform temperature heating from below. Sha dowgraph and particle images have been used with temperature and salt conce ntration measurements to investigate the interface instability induced by c onvection when it is developing in the upper and lower layer. It is found t hat the interface is governed by local shear flow that induces a Kelvin-Hel mholtz instability. Moreover, the entrainment interface is subject to a com bination of two closely related effects: (1) double diffusion and convectiv e motion and (2) double diffusion and Kelvin-Helmholtz instability.