Abstract

The initial stages of sea ice formation in a turbulent ocean typically involve the growth of a suspension of frazil ice crystals in supercooled waters. Eddies in the fluid flow act to keep the crystals suspended, while the relative buoyancy of the crystals causes them to rise, eventually sedimenting to form a layer of ice. The resulting granular ice has been observed to make up a significant fraction of ice cover in certain locations. Here, we consider the interaction between the fluid dynamics of a suspension of crystals and the thermodynamics of phase change governing the growth and melting of the crystals. The growth of these crystals is dynamically coupled to the fluid flow: advection enhances the transport and removal of latent heat that controls crystal growth, whilst the particles provide hydrodynamic and thermal feedbacks on the flow. We use a combination of scaling analysis, linear stability analysis and direct numerical simulation to illustrate the important features of this multiphase flow.