Fluid Dynamics - understanding fluid dynamics to improve our lives

许多地球物理流体动力系统的一个吸引人的特征是它们倾向于形成层或“阶梯”，其中一个关键物理量(例如，密度)显示出随深度的阶梯结构。例如，这可能发生在强迫湍流、双扩散对流(导致海洋学上的温盐阶梯)和旋转流动(导致木星上的喷流所显示的潜在涡度阶梯)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。它将专注于二维流体流动，这种流动相对容易模拟，并提供检查地层结构所需的高分辨率。它将首先研究分层流体中的强迫流动，特别强调确定导致(和不导致)分层的强迫的性质，以及确定可能发生分层的参数制度。然后，它将转向双扩散分层问题。尤其令人感兴趣的是确定薄界面中到底发生了什么，以及这些界面如何连接到更广泛的层中的流体流动。将根据它们与海洋学和实验观测的关系以及与现有分层过程简化模型的关系来分析所获得的所有结果。

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.