Vortex Tubes, Spirals and the Large-Eddy Simulation of Turbulence

项目编号：CTS-0227881PRINCIPAL REQUESTER：Dale I.PULLININT：加利福尼亚理工学院涡管、螺旋线和涡流的大涡模拟这项研究旨在进一步发展拉伸的涡流作为湍流细尺度模拟和湍流大涡模拟(LES)的基于结构的亚网格尺度模式的基本元素的思想。所面临的挑战是在大雷诺数的实际湍流中，建立对小尺度动力学及其在大尺度上的影响的统一描述。这种模拟方法将被应用于建立湍流近壁区的特殊亚网格尺度模式，用于尾涡的大涡模拟以及湍流混合中速度-标量关系的研究。将进行的研究将包括：(1)发展和试验一个特殊的亚网格尺度的壁面边界湍流近壁区模式。这一过程的定量描述是基于近乎纵向的亚层涡对局地平均跨向剪切的扭曲/缠绕。(2)具有大尺度应变的复杂非定常流动的大涡模拟，如高雷诺数的湍流尾涡。这涉及到具有平均流线曲率的高度各向异性的非定常流动的演变，该流动受到强烈的内部大尺度旋转和应变的影响。所提出的大涡模拟将使用实际的初始条件，并结合一个模型，在涡核内产生由诱导的轴向压力梯度产生的轴向流动。(3)将小尺度湍流的拉伸螺旋-旋涡模型应用于分析存在平均标量梯度的均匀湍流中的速度-标量相关性。之所以选择这些应用领域，是因为它们分别代表了大雷诺数下湍流的建模、计算和分析中的重要问题。

ABSTRACTPROPOSAL NO.: CTS-0227881PRINCIPAL INVESTIGATORS: DALE I. PULLININSTITUTION: CALIFORNIA INSTITUTE OF TECHNOLOGY VORTEX TUBES, SPIRALS AND THE LARGE-EDDY SIMULATION OF TURBULENCEThis study aims to further develop the idea of the stretched vortex as the fundamental element for both the modeling of the fine-scales of turbulence and for the building of structure-based subgrid-scale models for the Large-Eddy Simulation (LES) of turbulent flows. The challenge is to develop a unified description of the small-scale dynamics and their effect on the larger scales in realistic turbulent flow at large Reynolds numbers. This modeling approach will be applied to the construction of a special subgrid scale model for the near-wall region of turbulent flow, to the LES of trailing vortices and to the study of velocity-scalar correlations in turbulent mixing. The research to be conducted will include:(1) development and testing of a special subgrid-scale model for the near-wall region of wall-bounded turbulent flows. A quantitative description of this process is developed based on the distortion/winding of the local mean spanwise shear by a nearly longitudinal sublayer vortex. (2) LES of complex unsteady flows with high large-scale strain, such as the turbulent trailing vortex at high Reynolds number. This involves the evolution of a highly anisotropic, unsteady flow with mean streamline curvature that is subject to strong internal large-scale rotation and strain. The proposed LES will use realistic initial conditions combined with a model for the production, inside the vortex core, of axial flow generated by an induced axial pressure gradient.(3) application of the stretched-spiral-vortex model of turbulence small scales to the analysis of velocity-scalar correlations in homogeneous turbulence in the presence of a mean scalar gradient. These application areas are chosen because they represent, respectively, important problems in the modeling, computation, and analysis of turbulent flows at large Reynolds numbers.