2014 Small World In Motion Competition

Oil film floating on water

Dr. John Hart

University of Colorado Boulder
Department of Atmospheric and Oceanic Sciences
Boulder, Colorado, USA

Reflected Light Differential Interference Contrast (Nomarski)


Thin film of volatile oil floating on a water surface.  Evaporation occurs in isolated pools a few microns deep.  Flow instabilities at the edges bring oil into the centers of the pools, forming droplets.  Coalescence leads to bigger drops that have more volume per unit of surface area, and slower evaporation.  Interference colors dramatize the motions.  The complex microscopic fluid dynamics are relevant to the longevity of fuel spills.