Thermocapillary Effects on Fluid Distributed on Wettability-Confined Tracks
thesisposted on 31.10.2017, 00:00 by Antonio Lafratta
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.