Charge and Mass Transfer with Inherent Electric Field Prediction

A mathematical model is presented that predicts a multi-dimensional grid of concentrations and electric potential gradients in systems with coupled anodic and cathodic regions. Transport of charged species is assumed to occur via diffusion, convection, and electromigration due to the predicted electric potential field, in a moderately dilute electrolyte. The electric potential field is assumed dependent on the coupled anodic and cathodic regions, concentration gradients, and deviations from electroneutrality. This model is capable of accurately predicting the transport (and potential gradients) occurring within and outside of a corroding crevice without any experimental knowledge of electric potentials. Predictions from this model show the two dimensional concentration and potential gradients caused by the flow of current through a sudden expansion/contraction, somewhat similar to the mouth of the crevice.