Drop solidification experiments on static and moving substrates, for varying feeding rates.

Inspired by problems of 3D printing that are currently motivating a large number of works, we consider two situations of liquid drops on a cold substrate, below the melting temperature :
- In a first set of experiments, a solidifying liquid drop is fed with liquid at constant flow-rate through a thin needle. This problem generalizes the cusp formation problem («pointy ice drops») investigated recently (A. Marin et al. Phys. Rev. Lett. 113, 054301 (2014)). Depending on control parameters (initial angle and flow-rate), two very different shapes are observed, concave and convex, for which we provide a simple model, that is in very good agreement with experiments.
- In a second set of experiments, the drop of sits on a cold moving substrate. Instabilities of the advancing contact lines are observed with a transition between continuous sliding and stick-slip behavior. We also propose a simple kinematical model that well describes this unstationnary dynamics. Experiments that combine both effects (continuous supply and substrate motion) are also under way.