Marangoni convection in droplets on superhydrophobic surfaces
Daniel Tam(American Institute of Aeronautics and Astronautics), Volkmar von Arnim(Massachusetts Institute of Technology), Gareth H. McKinley(Massachusetts Institute of Technology), A. E. Hosoi(Massachusetts Institute of Technology)
Cited by 173Open Access
Abstract
We consider a small droplet of water sitting on top of a heated superhydrophobic surface. A toroidal convection pattern develops in which fluid is observed to rise along the surface of the spherical droplet and to accelerate downwards in the interior towards the liquid/solid contact point. The internal dynamics arise due to the presence of a vertical temperature gradient; this leads to a gradient in surface tension which in turn drives fluid away from the contact point along the interface. We develop a solution to this thermocapillary-driven Marangoni flow analytically in terms of streamfunctions. Quantitative comparisons between analytical and experimental results, as well as effective heat transfer coefficients, are presented.