Selected-Eddy Simulations (SES): a revolutionary approach for turbulence simulations
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abstract
Turbulent flows can be extremely complex and often not well understood. This lack of fundamental understanding limits our ability to accurately predict the climate, dispersion of pollutants in the atmosphere and the ocean, and to design optimally efficient engines, transportation vehicles, and energy generation systems. Turbulence has a wide range of scales which makes experimental measurements and computational predictions challenging. Over the past 4 decades, significant progress has been made through direct numerical simulations (DNS) which resolve all relevant turbulent scales to improve turbulence models that are critical in automotive and aircraft design. However, DNS are computationally prohibitive in realistic scenarios. The main objective of this project is to develop a potentially transformative approach to simulate turbulent flows, capturing the detailed physics at a fraction of the cost of DNS while improving the accuracy of unsteady turbulent predictions. The project will seek to involve Hispanic men and women students; the principal investigator actively collaborates with several Hispanic organizations to enhance Hispanic students’ experiences, education, and quality of life on campus. This project aims to develop a revolutionary new approach for accurate turbulence simulations at a fraction of the cost DNS and with significant advantages over other low-order approaches such as Large-Eddy Simulations (LES), where large-scale turbulence is computed and smaller scales are modelled. The new approach, termed Selected-Eddy Simulations (SES), is based on solving a subset of scales across the entire spectrum, unlike LES which is limited to low wavenumbers. Thus, SES uses the true dynamics of the Navier-Stokes equations over a subset of all scales. This has tremendous advantages in reproducing Navier-Stokes dynamics especially in flows where small-scale features are critical such as mixing of weakly diffusive species, dispersion of small particles, shocks, and flames. The selection of modeled scales are control parameters in SES. The SES modeling approach will be compared with DNS and LES results to assess accuracy versus computational cost. The study and modeling of unresolved modes will provide insights into the physics of energy transfer and the dynamics of turbulence in general. Thus, a successful SES concept will result in a more complete understanding of the role of turbulent scales and a more accurate, potentially less expensive, computational tool that can be used to predict and control flows critical for a wide range of engineering applications. 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.
