Diffusion impedance finite Schmidt number

A similar development was provided by Tribollet and Newman for electro-hydrodynamic impedance. The use of look-up tables facilitates regression of models to experimental data that take full accoimt of the influence of a finite Schmidt number on the convective-diffusion impedance. Use of only the first term in equation (11.97) yields a numerical solution for an infinite Schmidt number. Tribollet and Newman report use of the first two terms in equation (11.97) The low level of stocheistic noise in experimental data justifies use of the three-term expansion reported here. 

Several authors have addressed the influence of a finite vedue of the Schmidt number on expressions for the convective-diffusion impedance. Levart and Schuh-mann showed that the concentration term could be expressed as a series expansion in Sc i.e.. 

A graphical method was reported by Tribollet et al. that can be used to extract Schmidt numbers from experimental data in which the convective-diffusion impedance dominates. 3 The technique accounts for the finite value of the Schmidt... 

It should be noted that the aforementioned model deals with the semi-infinite diffusion, which is presented by Warburg impedance. As the diffusion layer of finite thickness 5 is formed at the RDE surface, it is necessary to meet certain relations between 5, specified by Eq. (3.5), and the depth of penetration of the concentration wave Xq = y/2Dfco. Investigations in this field show [25,26] that the two aforementioned diffusion models are in harmony when < 0.15. At Schmidt number Sc = v/D = 2000, this condition is satisfied when co > 6 2 (or/ > 0.1m, where m is rotation velocity in rpm). 

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