Singularity-free description of moving contact lines for volatile liquids.

For a liquid advancing or receding on a flat bare solid in a vapor atmosphere, we show that no singularities in fact arise at the contact (triple) line. Contrary to common expectations, this does not require any "regularizing" microscopic effect (such as slip at the substrate, disjoining pressure or precursor films). The key here is the Kelvin effect, i.e., a curvature-induced variation of saturation conditions. Importantly, no evaporation-related singularities appear either. We proceed within the lubrication approximation and a classical one-sided model for zero or finite contact angle.