Nonlinear interactions between fluid flows inside and outside of sea ice

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Arctic sea ice is one of the most sensitive components of the Earth's climate system. Its importance stems from its relatively large albedo that reflects a substantial portion of the incoming shortwave radiation back to space, thereby playing an important role in the Earth's radiation budget. Understanding the evolution of sea ice is critically important in accurately predicting changes in the Earth's climate.Unlike pure ice, sea ice is a reactive porous medium which contains pockets of brine which are trapped during rapid solidification. This reactive porous medium is referred to as a mushy layer. The interactions between fluid flows inside and outside of the mushy layer determine the turbulent transport of salt, momentum and heat to the mushy-layer-ocean interface. To understand these interactions, one needs to study the buoyancy driven flows in the mushylayer and the underlying ocean in the presence of mean shear. The dynamics of sea ice, and mushy layers generally, forced by an exterior flow remains an open problem in fundamental fluid mechanics. It presents a rich mathematical system to explore, with significant implications for understanding a key aspect of the climate system. The proposal of this project is to develop new analytical and numerical methods to address this problem.The proposed project aims to combine direct numerical simulations and mathematical theory to study these interactions. A combination of the Lattice Boltzmann (LB) and enthalpy methods will be used for this. The LBM is a highly effective tool for simulating flows over random, evolving geometries and is also amenable to easy parallelization. The simulations will be used to provide a detailed picture of these interactions, and the data from the simulations will be used to develop simplified mathematical models for the transport of heat and salt to the mushy layer from the underlying ocean.