CAREER: Turbulence-Resolving Integral Simulations for Boundary Layer Flows

湍流在与能源、运输和国家安全有关的各种边界层流动中起着关键的物理作用。因此，提高边界层湍流的模拟能力是加速工程设计、优化和认证的关键，同时降低相关成本。实例应用包括湍流对飞机或风力涡轮机叶片气动力影响的建模，以及高超声速飞行器的强烈气动加热。尽管超级计算机的性能取得了巨大的进步，但仅使用基本物理定律直接模拟这些和其他类似重要的流动，通常要么不切实际，要么完全不可行。这种困难是由于极高的计算要求与大范围的尺寸，湍流涡流运动可以有。因此，需要创新的近似方法来创建实用的仿真工具，在不牺牲太多精度的情况下降低计算成本。该项目引入了一种新的模拟框架，该框架基于二维流动表示中最大，最具影响力的湍流运动的直接分辨率。该方法将首先用于低速流动，然后将其扩展到解决与高超声速飞行器边界层相关的挑战。从技术角度来看，潜在的变革性模拟框架的发展可以影响与社会最紧迫挑战相关的各种应用。课堂内外的创新教育活动将与项目的研究活动相结合。该项目的总体目标是引入和发展湍流解决积分模拟计算湍流边界层动力学。虽然基于积分的方法已经很好地建立用于边界层，但现有的方法是基于平均方程的。所提出的模拟框架将通过考虑在湍流边界层的二维描述中直接解决大尺度和超大尺度运动的基于积分的模拟而开辟新天地。在建立了该方法的基本能力之后，将特别关注现有建模技术难度较大的场景，包括受非零自由流压力梯度影响的边界层和具有高焓效应的高超声速边界层。在评估新模拟方法的成功时，将特别注意物理保真度和计算效率之间的权衡。综合教育活动将形成多管齐下的努力，以扩大本科生到研究生的管道，提高学生对研究生的准备和流体动力学科学计算的能力。该奖项反映了美国国家科学基金会的法定使命，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。

Turbulence plays a key physical role in a wide variety of boundary layer flows related to energy, transportation, and national security. As such, improving simulation capabilities for boundary layer turbulence holds the key to accelerating engineering design, optimization, and certification while reducing associated costs. Example applications include the modeling the impact of turbulence on aerodynamic forces on airplanes or wind turbine blades, and the intense aerodynamic heating of hypersonic vehicles. Despite enormous advances in supercomputer performance, direct simulations of these and other similarly important flows, using only the basic laws of physics, are typically either impractical or completely infeasible. This difficulty is due to the extremely high computational requirements associated with wide range of sizes that turbulent eddying motions can have. As a result, innovative approximation methods are required to create practical simulation tools by reducing computational cost without sacrificing too much accuracy. This project introduces a new simulation framework based on the direct resolution of the largest, most influential turbulent motions within a two-dimensional representation of the flow. The method will be developed first for low-speed flows before extending it to tackle challenges related to boundary layers on hypersonic vehicles. From a technical perspective, the development of a potentially transformative simulation framework can impact a wide variety of applications related to society’s most pressing challenges. Innovative educational activities within and outside the classroom will be integrated with the research activities of the project.The overarching goal of the project is to introduce and develop turbulence resolving integral simulations for computing turbulent boundary layer dynamics. While integral-based methods have been well established for use with boundary layers, existing approaches are based on averaged equations. The proposed simulation framework will break new ground by considering integral-based simulations that directly resolve large and very-large scale motions in a two-dimensional description of the turbulent boundary layer. After establishing the basic competence of the approach, particular attention will be given to scenarios for which existing modeling techniques have greater difficulty, including boundary layers subjected to non-zero freestream pressure gradients and hypersonic boundary layers with high-enthalpy effects. In evaluating the success of the new simulation method, particular attention will be given to the trade-off between physical fidelity and computational efficiency. Integrated educational activities will form a multi-pronged effort to broaden the undergraduate-to-graduate pipeline and improve student readiness for graduate school and competence in scientific computing for fluid dynamics.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.