Some effects of limited wall-sensor availability on flow estimation with 3D-GANs

TL;DR

This study evaluates how limited wall-sensor data affects 3D flow field estimation in turbulent channels using GANs, highlighting the importance of sensor placement and noise robustness for practical applications.

Contribution

It demonstrates the impact of sensor quantity and placement on flow estimation accuracy using 3D-GANs, and assesses noise effects, advancing practical flow measurement methods.

Findings

Accuracy mainly affected by spatial undersampling of scales.

Pressure sensors outperform shear stress sensors with many sensors.

Fewer sensors are less sensitive to measurement noise.

Abstract

In this work we assess the impact of the limited availability of wall-embedded sensors on the full 3D estimation of the flow field in a turbulent channel with Re{\tau} = 200. The estimation technique is based on a 3D generative adversarial network (3D-GAN). We recently demonstrated that 3D-GANs are capable of estimating fields with good accuracy by employing fully-resolved wall quantities (pressure and streamwise/spanwise wall shear stress on a grid with DNS resolution). However, the practical implementation in an experimental setting is challenging due to the large number of sensors required. In this work, we aim to estimate the flow fields with substantially fewer sensors. The impact of the reduction of the number of sensors on the quality of the flow reconstruction is assessed in terms of accuracy degradation and spectral length-scales involved. It is found that the accuracy degradation is mainly due to the spatial undersampling of scales, rather than the reduction of the number of sensors per se. We explore the performance of the estimator in case only one wall quantity is available. When a large number of sensors is available, pressure measurements provide more accurate flow field estimations. Conversely, the elongated patterns of the streamwise wall shear stress make this quantity the most suitable when only few sensors are available. As a further step towards a real application, the effect of sensor noise is also quantified. It is shown that configurations with fewer sensors are less sensitive to measurement noise.