Modeling of the Subgrid-scale Pressure-Strain-Rate Correlation in the Atmospheric Surface Layer

本文主要研究大气边界层大涡模拟中的亚网格模式。 大涡模拟已经成为大气边界层研究的有效工具，也是最重要的模拟方法，但在近地层，大涡模拟存在固有的低分辨率和亚网格尺度（SGS）模式性能差的问题。 本研究将通过分析现场测量数据、建模和数值模拟来解决这个问题，以提高SGS模型的性能。 特别是，重点将放在SGS压力-应变率相关性的建模上，这是这种建模方法的主要挑战。 最近的平流水平阵列湍流研究（AHATS）现场计划揭示了这个变量的新行为，作为对流表层SGS应力各向异性的原因，与广泛接受的恢复各向同性的作用的理解相矛盾。 有了这些知识，SGS的压力-应变-速率相关的物理将进一步研究，和新的输运方程models.Intellectual优点：该研究将解决的SGS压力-应变-速率相关性建模的关键问题SGS应力输运方程为基础的SGS建模LES的ABL。预计将显着推进的SGS应力和温度通量的动态的理解。 由于SGS压力-应变率相关性在SGS应力动力学中的核心作用，对这种相关性的物理学的新理解将对未来的SGS建模产生深远的影响。 模型开发活动将是将新的SGS物理学纳入SGS模型的第一步。更广泛的影响：研究在几个领域产生了更广泛的影响。 它将为研究生和本科生提供教育和研究机会。 改进近地面层湍流和大气边界层的预报对于发展大气扩散和扩散、天气预报、大气化学、风能和陆-气交换的预报模式具有重要意义。建模方法对于建模具有强压力梯度的边界层（例如，弯曲边界层）。这些领域的进步将有利于环境和社会。

The research focuses on subgrid-scale modeling in large-eddy simulation (LES) of the atmospheric boundary layer (ABL). LES has become an effective research tool for the ABL and probably the most important simulation method for it. However, in the surface layer LES suffers from inherent under-resolution and poor subgrid-scale (SGS) model performance. This study will address this problem through analysis of field measurement data, modeling, and numerical simulations to improve SGS model performance.Issues in SGS modeling based on the SGS stress and flux transport equations will be analyzed. In particular, the focus will be put on modeling of the SGS pressure-strain-rate correlation, which is the main challenge in this modeling approach. Recent Advection Horizontal Array Turbulence Study (AHATS) field program has revealed new behavior of this variable as the cause of anisotropy in the SGS stress in the convective surface layer, contradicting the widely accepted understanding of its role of return to isotropy. With this knowledge, the physics of the SGS pressure-strain-rate correlation will further be investigated, and new transport equation models will be developed.Intellectual Merit:The research will address the critical issue of modeling the SGS pressure-strain-rate correlation in SGS stress transport equation-based SGS modeling for LES of the ABL. It is expected to significantly advance the understanding of the dynamics of the SGS stress and temperature flux. Due to the central role of the SGS pressure-strain-rate correlation in the SGS stress dynamics, new understanding of the physics of this correlation will have a profound impact on future SGS modeling. The model development activities will be a first step towards incorporating the new SGS physics into SGS models.Broader Impacts:The research has broader impacts in several areas. It will provide education and research opportunities for graduate and undergraduate students. Improved prediction of the surface layer turbulence and the ABL in general will be of importance to developing predictive models for atmospheric dispersion and diffusion, weather forecasting, atmospheric chemistry, wind energy, and land-atmosphere exchange. The modeling approach will also be important for modeling boundary layers with strong pressure gradient (e.g., curved boundary layers) in the ABL and in engineering flows. Advances in these areas will benefit the environment and society.