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Résumé |
A pencil can be pushed into a viscous liquid at high speed without the risk of entraining air with it: contact lines advancing over a solid are very stable. If the pencil is pulled out again, a dynamic wetting transition is observed at a moderate speed, and a film of liquid is pulled up with the solid: a receding contact line cannot be sustained above a critical speed. In this talk we explain, both in physical and in mathematical terms, the reason for the qualitatively different behavior of advancing and receding contact lines. We solve the dynamic wetting problem, both below and above the transition. Finally, we solve the problem of a thin film receding from a solid substrate. |
