The physics of freezing and melting in the presence of flows

Ice in the environment plays a central role in both global-scale processes on Earth and many human activities. Issues related to its description, including the modelling of natural ice dynamics from the smallest to the largest scales, are of great importance. In the natural environment, melting or freezing processes are typically coupled to those of fluid flows. Therefore, the interplay between fluid mechanics and phase-change thermodynamics is a highly topical problem. In recent years, fluid–ice interface problems have been studied via not only field measurements but also laboratory experiments, numerical simulations and theoretical analyses. This Perspective considers the state-of-the-art knowledge of the phenomenology of fluid–ice coupling processes in standardized configurations. These include freezing and melting in thermally stratified natural convection of fresh water, double-diffusive convection and convection in the mushy ice of salty water in confined systems, as well as imposed flows moving along an ice layer or surrounding dispersed ice bodies. It also highlights open questions of geophysical interest that could benefit from fundamental studies with a physical and fluid dynamic approach. The dynamics of water freezing and ice melting in natural environments involves many intricate fluid mechanics processes. To tackle these complexities, examining them in well-controlled laboratory settings proves highly advantageous.