PROFILE AT A CONTACT LINE FOR EVAPORATING SESSILE DROPS AND VISUALIZATION OF CAPILLARY FLOW

The drop-refractive shadowgraph method is successfully applied to visualize thermocapillary convection flows in sessile drops. Different flow patterns are observed from the drop-refractive far-field shadowgraphic images of the sessile drops. The analysis based on a wave theory for caustics and caustic diffraction leads a new method to identify the profile near the three-phase-line region and estimate the drop-foot height, which is important for the study of spreading of evaporating liquid drops.