Shaping liquid and solid water interfaces - E. Jambon-Puillet (Princeton)

In this talk, I will show two very different situations which have in common a body of water that we reshape and describe the physical mechanisms driving these changes of morphology.

First, I will talk about the singular evaporation/sublimation of ice. Ice being a solid, an ice body can have a complex geometry (e.g. a snowflake) which makes its precise evaporation dynamics challenging to predict. Here, we study the sublimation of snowflakes and pointy ice drops. We show that sublimation is limited by the diffusion of the water

vapour

which allows us to predict ice and snowflake evaporation quantitatively; by solving the diffusive free boundary problem, we correctly predict the rapid self-similar evolution of sharp edges and points, a results more generally applicable to other diffusion problems such as the dissolution of salt crystals or pharmaceuticals.

Then, I will describe how to form liquid helices. From everyday experience, we all know that a solid edge can deflect a liquid flowing over it significantly, up to the point where the liquid completely sticks to the solid. By grazing vertical cylinders with inclined capillary liquid jets, we here use this so-called teapot effect to attach the jet to the solid and form liquid helices. Using mass and momentum conservation along the liquid stream, we quantitatively predict the shape of the helix and provide a parameter-free inertial-capillary adhesion model for the critical velocity for helix formation.