A Theoretical and Numerical Study of 2D and 3D Flow over Dynamically Tall Mountain Ranges

本研究将使用理论和数值模拟相结合的方法来研究模拟的、动态变化的山脉高度上的分层气流的作用，以确定何时气流必须以全三维气流为特征，何时二维框架足以模拟这种气流。 这项研究的更广泛的影响将服务于航空和消防安全领域的山区气象界，以及小规模流动的微气象学。 拟议的研究旨在使用计算流体动力学（CFD）的方法来模拟三维流动动态高大的山脉。 数值结果将被分析，以确定何时以及为什么这些流分裂。 该建议包括对这些流量分裂的早期理论的改进，并可能发展一个新的理论基础，特别是对沿脊流量变化。 最近的理论分析表明，上游阻塞流和背风面非对称、超临界、下坡流之间存在定量联系。 解决粘性边界层，流动分离和非流体静力剪切不稳定性的模拟表明，这些流动从山脊分离，并形成一个内部的液压泵下游的分离点。 这项研究将调查这个分离点作为无量纲的山的高度和某些热特性，如山脉之间的山谷中的冷池的函数。

This research will use a combination of theory and numerical simulation to study the role of stratified air flow over simulated, dynamically varying mountain range heights to determine when the flow must be characterized by fully 3-dimensional flow and when a 2-dimensional framework will suffice to model this flow. The broader impact of this research will serve the Mountain Meteorology community in the areas of aviation and fire safety, as well as micrometeorology of small scale flows. The proposed research seeks to use a Computational Fluid Dynamics (CFD) approach to simulate 3-dimensional flow over dynamically tall mountain ranges. Numerical results will be analyzed to determine when and why these flows split. The proposal includes a refinement of earlier theories on these flow splits and potentially the development of a new theoretical basis; particularly for the along-ridge flow variability. Recent theoretical analyses have shown the quantitative connection between blocked flow upstream and asymmetric, supercritical, downslope flow in the lee. Simulations that resolve viscous boundary layers, flow separation and non-hydrostatic shear instabilities suggest these flows separate from the ridge and form an internal hydraulic pump downstream of the separation point. This study will investigate this separation point as a function of dimensionless mountain height and certain thermal characteristics such as the cold pool in the valley between mountain ranges.