Large Eddy Simulation in Complex Turbulent Flows with Coarse Resolution

流体流动的计算模拟对于各种技术的工程至关重要。通常，这些模拟的效用受到湍流效应的不可靠模型的限制。这里提出的研究旨在开发用于大涡模拟的模型，使复杂流动中的湍流的实际和可靠的模拟。通过开发真正可靠和广泛适用的湍流模型，拟议的研究将在航空，推进，发电和风能等领域产生深远的影响，并有可能实现对我们国家和社会重要的技术的重大改进。这一潜在影响的严重程度很难被夸大。此外，通过对研究生和大学生暑期实习生进行复杂物理系统数学模型开发方面的培训，该项目将有助于培养解决我国和世界面临的广泛复杂问题所需的高技能劳动力。大涡模拟（LES），其中模拟最大尺度的湍流，同时模拟较小尺度的影响，是可靠预测湍流效应的最有前途的方法之一。然而，目前可用的模型的可靠LES的分辨率要求通常是不切实际的复杂的湍流的技术利益。从本质上讲，对于实际应用，模拟必须尽可能粗的分辨率是可靠的，这通常违反了制定模型的假设，使其无效。新的建模方法和工具，可以解决所提出的挑战，粗解决LES已经开发。这些包括一个模型分裂配方，使子网格模型，以履行不同的角色，离散化意识的模型配方，以解决数值离散化的影响，和统计模型，允许的LES的性能进行预测和模型进行优化。模型和工具需要在几个方面进行推广，使可靠的粗分辨LES在复杂的流动应用，这种推广是本建议的主题。广义模型将进行测试，直接数值模拟，不需要建模，实验数据，以评估其可靠性，局限性和分辨率要求。该项目更广泛的影响目标包括对复杂湍流的可靠模型所实现的广泛技术的影响，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Computational simulation of fluid flows is critical to engineering for a wide variety of technologies. Often, the utility of these simulations is limited by unreliable models for the effects of turbulence. The research proposed here is aimed at developing models for use in large eddy simulation that enable practical and reliable simulations of turbulence in complex flows. By developing truly reliable and broadly applicable turbulence models, the proposed research will have profound impacts in such fields as aeronautics, propulsion, power generation and wind energy, with the potential of enabling great improvements in technologies important to our country and society. The magnitude of this potential impact would be hard to overstate. In addition, by providing training for a graduate student and undergraduate summer interns in the development of mathematical models of complex physical systems, this project will contribute to the highly skilled workforce required to address a broad range of complex problems facing our country and the world.Large eddy simulation (LES), in which the largest scales of turbulence are simulated while the effects of smaller scales are modeled, is one of the most promising approaches to reliably predict the effects of turbulence. However, the resolution requirements for reliable LES with currently available models are generally impractical for complex turbulent flows of technological interest. In essence, for practical applications, it is necessary that the simulations be reliable for as coarse a resolution as possible, which generally violates the assumptions under which the models are formulated, rendering them invalid. New modeling approaches and tools that can address the challenges posed by coarsely resolved -LES have been developed. These include a model-splitting formulation to allow the subgrid models to fulfill different roles, discretization aware model formulations to address the effects of numerical discretization, and statistical models that allow the performance of a LES to be predicted and models to be optimized. The models and tools need to be generalized in several ways to enable reliable coarsely resolved-LES in complex flow applications, and such generalization is the subject of this proposal. Generalized models will be tested against direct numerical simulations, which require no modeling, and experimental data, to assess their reliability, limitations, and resolution requirements. The broader impact objectives of this project include the impact on a wide range of technologies enabled by reliable models for complex turbulent flows, and the training of a graduate student and undergraduate students in computational science and the modeling of complex physical systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.