A revisit of the electro-diffusional theory for the wall shear stress measurement.

0534262 - ÚCHP 2022 RIV US eng J - Journal Article
Havlica, Jaromír - Kramoliš, D. - Huchet, F.
A revisit of the electro-diffusional theory for the wall shear stress measurement.
International Journal of Heat and Mass Transfer. Roč. 165, Feb 2021 (2021), č. článku 120610. ISSN 0017-9310. E-ISSN 1879-2189
Institutional support: RVO:67985858
Keywords : boundary layer * electrochemical method * mass transfer
OECD category: Chemical process engineering
Impact factor: 5.431, year: 2021
Method of publishing: Limited access

This article intends to revisit the electro-diffusional theory for the wall shear stress measurement from mass transfer probes of rectangular shape by considering the existence of two components of the wall shear rate (i.e., axial and transversal). General analytical formulas for the effective transf er length and the dimensionless mass transport coefficient were derived as a function of two parameters: a dimensionless angle of the flow direction, relative to the leading edge of the probe, and the aspect ratio between the width and the length of the strip probe. The correctness of the analytical relations for arbitrary flow direction and the aspect ratio was confirmed by numerical solutions of the transport equation in the convective-diffusive regime. It has also been proved that the differences between the Lévêque solution and the general analytical formula exhibit a significant deviation for a specific range of parameters. In the case of the three-dimensional boundary layers, in addition to the magnitude of the wall shear stress, the direction of the fluid flow in the vicinity of the probe’s surface is of paramount importance. Accordingly, a measurement methodology is proposed using two strip probes with different aspect ratios. The resulting equations required to quantify the magnitude of the wall shear rate vector and the dimensionless angle are also derived.
Permanent Link: http://hdl.handle.net/11104/0313721