Oil in Alcohol

The elegant patterns formed by fluid droplets falling through a dissimilar liquid were first studied over a century ago.1 The emerging patterns are driven by hydrodynamic instabilities set up by velocity and density gradients between the liquids. We perform experiments using 3 mm droplets of naphthenic oil released from two heights (25 mm, 50 mm) into isopropyl alcohol. The oil is denser than and miscible in the alcohol (ρoil/ρal = ), which results in the drop descending and eventually diffusing. Images