Application of Large Eddy Simulation Methods to Complex Problems in Heat Transfer

迫切需要更好的方法来预测具有重要技术意义的湍流的热特征。尽管湍流模拟的各个层面都需要取得进展，但计算机技术的最新进展和对未来继续发展的展望表明，现在可能是时候加强对湍流的直接大涡模拟的研究，以将这些能力转向更大、更相关的问题。在这项研究中要特别强调的问题包括具有热传递的分离流动。这项研究的目的是：(1)更好地理解复杂的具有热传递的湍流流动(特别是分离流)，以确定改进的雷诺平均N-S方程的湍流模拟；(2)评估和比较几种亚网格尺度模型的特性，用于包括动态模型在内的具有热传递的湍流分离流动的大涡模拟；以及(3)致力于更有效的空间非周期流动的计算策略，以便利用现有的计算资源来处理更相关的问题。拟议的研究将试图对扩大基础知识和提高科学预测能力作出贡献，这是在燃气轮机发动机部件、电子设备(如数字计算机)等产品的设计程序和制造过程中保持竞争优势所必需的。直接的数值模拟将提供一些有换热的分离流动的基本知识，特别是后向台阶流动，这是很难用雷诺-平均的N-S方程来模拟的。将特别注意建立适用于有热传递的流动的动态亚网格尺度模型的优点和局限性。研究结果应提供有关流动与换热的基本新知识，并改进预测这种流动的手段，并将提高国家竞争力。

There is an urgent need for better methods of predicting the thermal features of turbulent flows that are technologically important. Although progress is needed at all levels of turbulence modeling, the recent advances in computer technology and the outlook for continued advances in the future suggest that it may be timely to give increasing attention to research on direct and large eddy simulation of turbulent flow to move these capabilities toward larger and more relevant problems. Problems to be given particular emphasis in this study include separated flows with heat transfer. The objectives of the proposed research are to: (1) develop a better understanding of complex turbulent flows (particularly separated flows) with heat transfer with a view toward identifying improved turbulence modeling for the Reynolds-averaged Navier-Stokes equations, (2) evaluate and compare the characteristics of several subgrid-scale models for the large eddy simulation of turbulent separated flows with heat transfer including a dynamic model, and (3) work toward a more efficient computational strategy for spatially non-periodic flows to allow more relevant problems to be addressed with current computational resources. The proposed research will attempt to make contributions both to the expansion of basic knowledge and to the advancement of the scientific predictive capability that is needed to maintain a competitive edge in design procedures for products such as gas turbine engine components, electronic devices (such as digital computers) and in manufacturing processes. The research will employ direct and large eddy numerical simulations based on a preconditioned finite-volume discretization technique to solve the compressible Navier-Stokes equations for turbulent flows with heat transfer. The direct numerical simulations will provide basic knowledge of some separated flows with heat transfer, particularly the rearward facing step flow, which have been very difficult to model through the Reynolds-avera ged Navier-Stokes equations. This information will guide the development of improved closure models for the Reynolds-averaged Navier-Stokes equations and aid in the evaluation of subgrid-scale models for the large eddy simulations. Particular attention will be given to establishing the merits and limitations of a dynamic subgrid-scale model suitable for flows with heat transfer. The results should provide fundamental new knowledge about flows with heat transfer and result in improved means of predicting such flows and will enhance national competitiveness.