Liquid drop dynamics under the effect of an induced horizontal wettability gradient

Abstract

A liquid drop, when placed over a rigid surface tends to obtain an equilibrium shape with minimum surface energy. The above phenomenon is a consequence of a number of parameters like density, contact angle, surface tension and volume of the droplet. The drop under consideration would remain static under the absence of any external force and contact angle gradient. With the effect of the above factors, it may so happen that the drop may self propel itself towards a direction that would minimize its surface energy. Depending upon the strength of the above factors, it may even be possible to move up the drop in any desired direction as per application requirements like cooling of hot spots in electronic equipments like laptops, controllers, electronic equipments, etc. The present study is based on the effect of an induced wettability gradient over a liquid drop with reference to its movement using VOF model with Finite Volume Method. Finally, horizontal drop mobility curves representing wettability gradient versus volume have been plotted(considering horizontal plane surface). Further attempts have been made to study other characteristics related to this phenomenon.