The Application of MHD Theory to Mass Transport

In applying Eq. (14) to mass transport-controlled electrolytic processes, an important step is the estimation of the effect of the imposed magnetic field strength on properties of the diffusion boundary layer. Since electrolyte density is space-variant in this layer, the right-hand side of Eq. (14) is nonzero, even if the low-Rem approximation [i.e., curl(j B) = 0] is invoked. This is clearly shown by the expanded form 

A somewhat different but equally valid interpretation is a decrease in the mean diffusion-layer thickness due to an increasing presence of the convective component of the convective diffusion process. 

The latter interpretation was successfully used to analyze natural convection at vertical plate electrodes by including a magnetic field-related term in the classical convective diffusion equation. The beneficial effect of the magnetic field on mass transport may be estimated from the ratio of the limiting current density in a magnetic field to that in its absence, called the augmentation factor  

In a cupric sulfate/sulfuric acid cell with vertical copper electrodes 

MHD-based models have been widely used in various magnetically assisted electrolyte flow investigations. 74,75 application of the pumping effect of combined electric and magnetic fields led to the development of MHD-pump electrode cells, where the concentration distribution, modeled by the classical convective diffusion equation 

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