On the inverse problem for two-component unsteady wall shear rate measurements: Application to the electrodiffusion method

TL;DR

This paper develops an inverse problem approach to accurately measure two-dimensional wall shear rates using electrodiffusion data, validated through numerical simulations in complex turbulent flows.

Contribution

It introduces a novel inverse method for wall shear rate measurement that outperforms existing post-treatment techniques in versatility and application range.

Findings

Method accurately retrieves shear rate in complex flows

Outperforms other post-treatment methods

Effective in turbulent three-dimensional flows

Abstract

The instantaneous two-dimensional wall shear rate is assessed through an inverse problem using mass transfer data from a three-segment electrodiffusion probe. The method is validated numerically in complex flow conditions involving (i) high amplitude periodic fluctuations on both wall shear rate magnitude and direction and (ii) direct numerical simulation (DNS) data from a turbulent three-dimensional channel flow. The approach is shown to outperform every other post-treatments available for mass transfer sensors, especially regarding its versatility and application range. The impact of the three-segment probe gap size is also examined numerically.