A5
 
Peclet number for the wall-tube electrode
 

The mass transport equation is:

(A5.1)

where (under a 1st order convection approximation):

(A5.2)
(A5.3)

and the hydrodynamic constant, a is given by1:

(A5.4)

Defining the dimensionless lengths:

R = r/re and Z = z/re(A5.5)

and substituting for R and Z, gives the dimensionless form of the mass transport equation:

(A5.6)

Similarly the velocity expressions become:

(A5.7)
(A5.8)

Substituting for vr and vz gives:

(A5.9)

Where Ps is the (shear rate) Peclet number:

(A5.10)

Hence:

a = a(R,Z,Ps)(A5.11)

However the dimensionless current:

(A5.12)

is calculated from the flux at the electrode surface, where Z = 0. Furthermore R is integrated out, thus the dimensionless current is a sole function of the Peclet number. Note that this result is only valid for a 1st order convection approximation.

References

1 W.J. Albery, S. Bruckenstein, J. Electroanal. Chem., 144, (1983), 105.