Nonlinear interactions between fluid flows inside and outside of sea ice

北极海冰是地球气候系统中最敏感的组成部分之一。它的重要性源于其相对较大的反照率，反照率将入射短波辐射的很大一部分反射回太空，从而在地球的辐射预算中发挥重要作用。了解海冰的演变对准确预测地球气候的变化至关重要。与纯冰不同，海冰是一种反应性多孔介质，其中含有在快速凝固过程中被捕获的盐水袋。这种反应性多孔介质被称为糊状层。糊状层内外流体流动之间的相互作用决定了盐、动量和热量向糊状层-海洋界面的湍流输送。为了理解这些相互作用，我们需要研究在平均切变存在的情况下，由浮力驱动的泥层和海底流动。海冰和糊状层在外力作用下的动力学，在基本流体力学中仍然是一个悬而未决的问题。它提供了一个丰富的数学系统来探索，对理解气候系统的一个关键方面具有重要意义。这个项目的建议是发展新的分析和数值方法来解决这个问题。提出的项目旨在结合直接数值模拟和数学理论来研究这些相互作用。晶格玻尔兹曼（LB）和焓法的结合将用于此。LBM是一种非常有效的工具，可以模拟随机的、不断变化的几何形状的流动，并且易于并行化。模拟将用于提供这些相互作用的详细图像，模拟数据将用于开发从底层海洋向糊状层输送热量和盐的简化数学模型。

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.