Predicting the wall-shear stress and wall pressure through convolutional neural networks

• URL: http://arxiv.org/abs/2303.00706v1
• Date: Wed, 1 Mar 2023 18:03:42 GMT
• Title: Predicting the wall-shear stress and wall pressure through convolutional neural networks
• Authors: Arivazhagan G. Balasubramanian, Luca Gastonia, Philipp Schlatter, Hossein Azizpour, Ricardo Vinuesa
• Abstract summary: This study aims to assess the capability of convolution-based neural networks to predict wall quantities in a turbulent open channel flow. The predictions from the FCN are compared against the predictions from a proposed R-Net architecture. The R-Net is also able to predict the wall-shear-stress and wall-pressure fields using the velocity-fluctuation fields at $y+ = 50$.
• Score: 1.95992742032823
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: The objective of this study is to assess the capability of convolution-based neural networks to predict wall quantities in a turbulent open channel flow. The first tests are performed by training a fully-convolutional network (FCN) to predict the 2D velocity-fluctuation fields at the inner-scaled wall-normal location $y^{+}_{\rm target}$, using the sampled velocity fluctuations in wall-parallel planes located farther from the wall, at $y^{+}_{\rm input}$. The predictions from the FCN are compared against the predictions from a proposed R-Net architecture. Since the R-Net model is found to perform better than the FCN model, the former architecture is optimized to predict the 2D streamwise and spanwise wall-shear-stress components and the wall pressure from the sampled velocity-fluctuation fields farther from the wall. The dataset is obtained from DNS of open channel flow at $Re_{\tau} = 180$ and $550$. The turbulent velocity-fluctuation fields are sampled at various inner-scaled wall-normal locations, along with the wall-shear stress and the wall pressure. At $Re_{\tau}=550$, both FCN and R-Net can take advantage of the self-similarity in the logarithmic region of the flow and predict the velocity-fluctuation fields at $y^{+} = 50$ using the velocity-fluctuation fields at $y^{+} = 100$ as input with about 10% error in prediction of streamwise-fluctuations intensity. Further, the R-Net is also able to predict the wall-shear-stress and wall-pressure fields using the velocity-fluctuation fields at $y^+ = 50$ with around 10% error in the intensity of the corresponding fluctuations at both $Re_{\tau} = 180$ and $550$. These results are an encouraging starting point to develop neural-network-based approaches for modelling turbulence near the wall in large-eddy simulations.

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