A continuum multi-phase and multi-component description of the freezing process of seawater to porous sea ice

Abstract Formation of porous 'pancake' ice floes in the Antarctic Marginal Ice Zone (MIZ) is a complex phenomenon associated with interactions between the saline seawater and temperature. Ocean warming and future environmental conditions in the Southern Ocean will most likely have an impact on the porous microstructure and thus, also on the connected biogeochemical processes which are closely related to the ice formation. Hence, it becomes important to realistically model the phase transition phenomena. In this paper, a biphasic model of solid ice and saline sea water is presented within the framework of the extended Theory of Porous Media (eTPM) using a continuum mechanical multi-phase and multi-component treatment. The phase transition between ice and brine is modeled using an interfacial mass transfer approach where the mass transferred is assumed as a jump across an interface which separates the phases. The mass production, hence, depends on the heat fluxes, specific enthalpies and the interfacial area. Moreover, the freezing point depression due to changing salinities can be implemented yielding a more detailed simulation. The system of equations results in a high-fidelity model and is simulated using the Finite Element Method (FEM). As proof of concept academic examples are presented.