Development of an Asymptotically-Reduced, Multiscale Model of Turbulent Boundary Layer Dynamics at Extreme Reynolds Numbers

[1437851] chini, Gregory .提出的研究目标是利用理论和独特的实验相结合，发展一种模拟边界层湍流的新方法。理解、预测和控制湍流边界层动力学的能力对于许多技术应用和科学上重要的过程是重要的。在我们生活的世界和行业中，乱流是普遍存在的。这项研究的成功可能会影响任何涉及湍流的工业过程，从而以新产品、提高能源效率、更安静的系统等形式带来社会效益。与地球物理和天体物理流动有关的问题也可以用一种新的、更精确的方法来处理。这个教育计划包括研究生和本科生的参与。该研究的主要目标是通过综合使用高雷诺数（Re）渐近性和高分辨率高Re实验，建立湍流边界层动力学的多尺度偏微分方程（PDE）模型。就其本质而言，模型开发过程将阐明所谓的“内/外”相互作用，因为当Re趋于无穷大时，这些相互作用与边界层演化有关。此外，多尺度偏微分方程的数值解比原始Navier？从Stokes （NS）方程中推导出它们，从而能够在其他难以接近的参数区进行模拟。所提出的模型将不同于其他最近的努力，因为该模型保留了第一原理基础，不依赖于系统输入或现象学假设。该模型所基于的多尺度分析汇集了湍流地球物理流动的渐近分析、高re剪切流的“精确相干结构”和典型湍流壁流的平均动力学方面的最新进展。目标模型是一个封闭的多尺度PDE系统，它相对于原始NS方程是自洽的和系统简化的。这些关键的尺度信息只有通过高分辨率的实验才能获得。在这方面，新罕布什尔大学流动物理设施（FPF）是世界上最大的流动物理质量边界层风洞，可以在极端雷诺数下进行高分辨率的速度和涡度测量。

1437851Chini, Gregory The goal of the proposed study is to use a combination of theory and unique experiments to develop a new approach to modeling turbulent flows in the boundary layer. The capacity to understand, predict, and control turbulent boundary layer dynamics is important for a multitude of technological applications and scientifically important processes. Turbulence is prevalent in the world we live in and in the industry. Success in this research could impact any industrial process that involves turbulent flow, with consequent societal benefits in the form of new products, improved energy efficiency, quieter systems, etc. Problems related to geophysical and astrophysical flows could also be approached in a new, more accurate way. The educational plan involves the participation of both graduate and undergraduate students.The main goal of the proposed research is to develop a multiscale Partial Differential Equation (PDE) model of turbulent boundary layer dynamics through the integrated useof high Reynolds number (Re) asymptotics and well-resolved high-Re experiments. By its very nature, the model development process will elucidate the so-called "inner/outer" interaction, as these are linked to boundary layer evolution as Re tends to infinity. In addition, numerical solutions of the multiscale PDEs promise to be less costly than direct numerical simulations (DNS) of the primitive Navier?Stokes (NS) equations from which they are derived, thereby enabling simulations in otherwise inaccessible parameter regimes. The proposed model will be distinct from other recent efforts, because the model retains a first principles foundation, with no reliance on system inputs or phenomenological assumptions. The multiscale analysis on which the model is based brings together recent advances in the asymptotic analysis of turbulent geophysical flows, of "exact coherent structures" in high-Re shear flows, and of the mean dynamics in canonical turbulent wall-flows. The target model is a closed multiscale PDE system that is self-consistently and systematically simplified relative to the primitive NS equations. This critical scaling information is only accessible through well-resolved, high-Re experiments. In this regard, the Univ. of New Hampshire Flow Physics Facility (FPF), which is the world's largest flow physics quality boundary layer wind tunnel, allows high-resolution measurements of velocity and vorticity at extreme Reynolds numbers.