Axel Huerre – Freezing and capillary flows

Laboratoire MSC, CNRS-Université de Paris, 75013 Paris.

Understanding the coupling between capillary flows (being during drop impacts, water trickling, etc…) and freezing is a key challenge for numerous aplications ranging from aeronautics to mettalurgy processes and environmental flows (e.g. ice stalactites).
The main physical originilaty in those problems comes from the strong coupling between the solidification front (the boundary between ice and water) and the free surface (the boundary between water and air), leading to peculiar shapes for the ice formed. I will present small examples where we built experiments in the lab enhancing this coupling between capillarity and solidification. I’ll start with a small river flowing on very cold surface. Physical ingredients from heat transfer equations and front propagation will allow to understand the experimental observation: the formation of a thin wall of ice getting higher when going down the surface. This example will be completed by small discussions on experimental resullts obtained when a droplet is deposited on a cold substrate or when a slab of foam is put in contact with such a substrate.