ORIGIN OF STRATIFICATION IN CREAMING EMULSIONS

Colloidal suspensions aging under gravity have long been known to spon taneously separate into layers. We demonstrate through flow visualizat ion experiments that a lateral temperature gradient as small as 10 mK/ cm can be responsible for such stratification and that strata correspo nd to a stack of convection rolls. A linear stability analysis suggest s that the onset of stratification results from a convective instabili ty peculiar to fluids with inhomogeneous mass densities subjected to l ateral thermal gradients.