Development and Implementation of Practical Optimal LES Models

项目编号：CTS-0352552 PRINCIPAL调查员：Robert D.MOSERINSTUTION：伊利诺伊大学，Urbana-CHAMPAIGNDEVELOPMENT和在许多技术设备中实施实用的最优大涡模拟，预测和/或控制湍流流动的影响是非常重要的，因为湍流的行为可能最终控制设备的性能。大涡模拟(LES)是对高雷诺数湍流流动进行可靠预测的最有前途的技术之一。在大涡模拟中，湍流的最大尺度被模拟，而最小尺度的影响被模拟。然而，要实现大涡模拟的全部潜力，还有许多挑战需要克服；这些挑战包括近壁湍流的处理和数值离散的影响，特别是在具有复杂几何形状的流动中。拟议研究的目标是产生能够在广泛的湍流范围内提供可靠预测的大涡模拟。方法是应用“最优大涡模拟”公式，即通过正式的优化过程建立大涡模拟模型。根据小分离多点速度关联式建立了最优大涡模拟模型。开发此类模型的主要剩余挑战是在不求助于大量经验数据的情况下获得所需的速度关联。所需的统计相关性将使用动态技术来开发，其中相关性是从运行模拟和理论考虑中估计的。当前项目中特别感兴趣的将是对近壁湍流、标量输送和可压缩性进行模拟。这一开发的结果将是一种广泛适用和准确的大涡模拟技术，该技术将在应用CFD程序中实现。最优大涡模拟将发展成为一种在大范围湍流中强有力的预报工具。这将对许多工程应用产生重大影响，而湍流是其中的主要现象之一。重要的例子有：燃气轮机发动机中的流动，多段高升力翼型上的流动，以及搅拌槽式反应器中的流动。有了可靠的LES模拟，这些和许多其他应用将享受改进的新设计，并因减少测试需求而降低设计成本。

ABSTRACTPROPOSAL NO.: CTS-0352552PRINCIPAL INVESTIGATOR: ROBERT D. MOSERINSTITUTION: UNIVERSITY OF ILLINOIS, URBANA-CHAMPAIGNDEVELOPMENT AND IMPLEMENTATION OF PRACTICAL OPTIMAL LES MODELS In many technological devices, it is of great importance to predict and/or control the effects of turbulent fluid flows, because the behavior of the turbulence may ultimately control the performance of the device. Large eddy simulation (LES) is one of the most promising techniques for reliable prediction of the high Reynolds number turbulent flows of technological interest. In LES, the largest scales of turbulence are simulated while the effects of the smallest scales are modeled. However, there are a number of challenges to overcome for LES to realize its full potential; these include the treatment of near-wall turbulence and the impact of numerical discretization, especially in flows with complex geometries. The objective of the proposed research is to produce LES models that will provide reliable predictions in a broad range of turbulent flows. The approach is to apply the "Optimal LES" formulation, in which LES models are developed through a formal optimization process. Optimal LES models are formulated in terms of small separation multi-point velocity correlations. The primary remaining challenge in developing such models is obtaining the required velocity correlations, without resorting to extensive empirical data. The required statistical correlations will be developed using dynamic techniques, in which the correlations are estimated from the running simulation and from theoretical considerations. Of particular interest in the current project will be modeling near-wall turbulence, scalar transport and compressibility. The results of this development will be a broadly applicable and accurate LES modeling technique, which will be implemented in application CFD codes. Optimal LES will be developed into a powerful predictive tool in a wide range of turbulent flows. This will have great impact on many engineering applications in which turbulence is one of the dominant phenomena. Important examples are: flow in gas turbine engines, flow over multi-element high-lift airfoils, and flow in stirred tank reactors. With reliable LES simulations, these and many other applications will enjoy improved new designs, and reduced design costs arising from the decreased need for testing.