Experiments in Fluids

, Volume 9, Issue 1–2, pp 43–48 | Cite as

Three-segment electrodiffusion probes for measuring velocity fields close to a wall

  • V. Sobolík
  • O. Wein
  • O. Gil
  • B. Tribollet


Three-segment electrodiffusion probes embedded in a wall allow to determine simultaneously the three kinematic parameters of flow close to the probe surface: the flow directionθ, the wall shear rateq, and the normal velocity coefficientA,v z = −A z2. A well-controlled three-dimensional flow, generated by a rotating disk, was used to demonstrate the capabilities of this new kind of electrodiffusion probes by comparing experimental results with the prediction based on the well-known hydrodynamical theory.


Velocity Field Probe Surface Normal Velocity Kinematic Parameter Hydrodynamical Theory 
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List of symbols


normal flow coefficient, Eq. (1)


axis of the adjustment rod, Fig. 2


concentration of depolarizer (mol/m3)


diffusivity of depolarizer (m2/s)


correction of total current on normal flow effect


reference direction of the probe, Figs. 1 and 3


Faraday constant (F = 96,464 C/mol)


normalized directional characteristic fors-th segment


Fourier coefficients of directional characteristics, Eq. (4) and Table 3


corrections of Fourier coefficients on normal flow effect, Eqs. (4) and (7)


limiting diffusion current throughs-th segment (A)


total current through the probe in dependence on its eccentricity (A)


transport coefficient, Eqs. (3) and (5)


number of electrons involved in redox reaction


axis of the rotating disk, Fig. 2


centre of the probe, Fig. 2


magnitude of vectorial wall shear rate (s-1)


components of vectorial wall shear rate


ratio of the currents in an eccentric and the central position of the probe, Eq. (15)


radial coordinate, eccentricity of the probe


eccentricity of the adjustment rod (r A =Ō Ā, Fig. 2)

r, Φ, z

polar coordinates on the rotating disk


effective radius of the probe (R = 0.337 mm)


macroscopic area of the probe (S = 0.357 mm2)

x, y, z

Cartesian coordinates moving with the probe


adjustment angle, Figs. 2 and 3


angle included between local radius-vectorō ¯P of the probe and local direction of flow, Fig. 3


angle included between reference directione x of the probe and local direction of flow, Fig. 3


theoretical prediction ofθ, Eq. (11)


theoretical prediction ofx, Eq. (14)


calculated from experimental data using Eq. (4)


kinematic viscosity (m2/s)


angle implied between gradient ofq and direction of flow, Eq. (8)


angular speed of the rotating disk (rad/s)


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • V. Sobolík
    • 1
  • O. Wein
    • 1
  • O. Gil
    • 2
  • B. Tribollet
    • 2
  1. 1.Institute of Chemical Process FundamentalsCzechoslovak Academy of Sciences6 SuchdolCzechoslovakia
  2. 2.LP 14 of C.N.R.S.University of P. and M. CurieParis Cedex 05France

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