https://doi.org/10.1140/epje/s10189-023-00314-6
Regular Article – Soft Matter
Neural networks for large eddy simulations of wall-bounded turbulence: numerical experiments and challenges
1
Center for Turbulence Research, Stanford University, Stanford, CA, USA
2
Sandia National Laboratories, Albuquerque, NM, USA
Received:
29
January
2023
Accepted:
22
June
2023
Published online:
17
July
2023
We examine the application of neural network-based methods to improve the accuracy of large eddy simulations of incompressible turbulent flows. The networks are trained to learn a mapping between flow features and the subgrid scales, and applied locally and instantaneously—in the same way as traditional physics-based subgrid closures. Models that use only the local resolved strain rate are poorly correlated with the actual subgrid forces obtained from filtering direct numerical simulation data. We see that highly accurate models in a priori testing are inaccurate in forward calculations, owing to the preponderance of numerical errors in implicitly filtered large eddy simulations. A network that accounts for the discretization errors is trained and found to be unstable in a posteriori testing. We identify a number of challenges that the approach faces, including a distribution shift that affects networks that fail to account for numerical errors.
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