Effect of Molecular Interactions in Thermocapillarity-Driven Flows*

The thermocapillarity effect can be used to generate the local thinning of a wetting thin liquid film supported by a solid substrate. This thinning process produces local thicknesses down to a scale of tens of nanometres, at which molecular interactions from the solid-liquid interface become relevant. Within the frame of the lubrication approximation, we show that gravity and Laplace pressures are negligible in these ultra-thin regions, leaving the disjoining pressure as the sole contribution opposing the thermocapillarity stress. This allows us to isolate and characterise the signature of van der Waals interactions in experiments performed with wetting liquids.