Pore-scale three-phase model for water phase transitions: impact of melt film generation on wet snow metamorphism

The snow microstructure dictates the fundamental thermo-mechanical and hydraulic properties of snow. Local gradients in temperature or air humidity actively drive microstructural changes in the snow, in a process known as snow metamorphism. Here, we focus on wet snow metamorphism, which occurs when temperature is close to the melting point and involves phase transitions amongst liquid water, water vapor, and solid ice.



We propose a pore-scale phase-field model that simultaneously captures the three relevant phase-change phenomena: sublimation (deposition), evaporation (condensation), and melting (solidification). The phase-field formulation allows to track the temperature evolution amongst the three phases and the water vapor concentration in the air. We extend the model to incorporate two-phase flow. Our three-phase model recovers the corresponding two-phase transition model when one phase is not present in the system.



We use 2D simplified geometries to explore the role of melt film generation and distribution in controlling the dynamics of snow metamorphism in contrast to the dry regime. Our 2D simulations also unveil the impact of humidity and temperature on the dynamics of wet snow metamorphism. Our model may be the basis to investigate other problems involving water phase transitions such as airplane icing or thermal spray coating.