Thermocapillary Effects on Fluid Distributed on Wettability-Confined Tracks

A study of the thermocapillary effect on a silicone oil distributed on wedge-shaped and straight wettability-confined tracks is conducted in order to demonstrate the effective mass transfer, due to a surface tension gradient, when a change in the thermal conditions of the system is induced. A superoleophilic track on an oleophobic background provides the means to confine the fluid on an appropriate steel sample, whilst a compact insulating setup is meant to accommodate the steel plate and to impart a specific temperature gradient by means of two Peltier micro modules. The distortion of the shape of the oil has been visualized and analyzed for both types of tracks, by using shadow photography and image processing with appropriate softwares. Globally, the effects of the Laplace pressure and gravity have been found to have a strong consequence when wedge-shaped tracks are considered, thus acting against the thermocapillary force. Furthermore, the importance of the track length, which seems to play a huge role in preventing the fluid movement when straight tracks are analyzed, has been noted and recorded, thus preparing a future study designed to produce more detailed results.