Fluid Dynamics - understanding fluid dynamics to improve our lives

许多地球物理流体动力系统的一个迷人特征是它们倾向于形成层或“阶梯”，其中关键物理量（例如，密度）呈现出具有深度的阶梯结构。例如，这可能发生在强迫湍流、双扩散对流（导致海洋热盐阶梯）和旋转流（导致木星上的喷流所表现的位涡阶梯）中。该项目将通过理想化的数值模拟来解决分层过程中的基本问题。它将集中在二维流体流动，这是比较容易模拟，并提供所需的高分辨率检查层结构。它将首先调查强迫流在分层流体，特别强调确定的强迫，做（和不）导致分层的属性，并在确定的参数制度分层可能发生。然后，它将转向双扩散分层的问题。特别令人感兴趣的是确定薄界面中发生了什么，以及这些界面如何与更广泛的层中的流体流动相连接。将分析所得的所有结果与海洋学和实验观测的关系以及与现有的分层过程简化模型的关系。

A fascinating feature of many geophysical fluid dynamical systems is their tendency to form layers or "staircases", in which a key physical quantity (e.g., density) exhibits a staircase structure with depth. This can happen, for example, in forced turbulence, in double-diffusive convection (leading to oceanographic thermohaline staircases) and in rotating flows (leading to the potential vorticity staircases manifested by the jets on Jupiter). The project will address fundamental questions in the layering process through idealised numerical simulations. It will concentrate on two-dimensional fluid flows, which are relatively easy to simulate and provide the high resolution needed to examine layer structure. It will first investigate forced flows in a stratified fluid, with particular emphasis on determining the properties of the forcing that do (and do not) lead to layering, and in determining the parameter regimes where layering can occur. It will then turn to the problem of double-diffusive layering. Of particular interest is to determine exactly what happens in the thin interfaces, and how these are connected to the fluid flow in the broader layers. All the results obtained will be analysed in terms of their relation both to oceanographic and experimental observations and to existing reduced models of the layering process.