Wetting or freezing? Investigating the spreading dynamics of water on ice

When capillary flows (spreading or impacting drops, films, rivulets) solidify, the inert substrate is replaced by a growing ice layer. In such cases, the adhesion of the liquid on the solid is modified, which can have a major impact on the flow geometry and constraints. In our experiments, we investigate the spreading of a liquid drop, hotter than the water melting temperature, on ice. This allows us to observe directly the combined and competing effects of capillarity and solidification. We find that the spreading and arrest features are different than in isothermal cases, but also different from similar experiments made on non-ice cold substrates. Our results point towards the idea that liquid water does not totally wet ice, and hence the existence of an ice-water contact angle, which has already been suggested in the literature.