CAREER: Turbulence-Resolving Integral Simulations for Boundary Layer Flows

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.