A practical way to model convection in non-agitated electrolytes

Many electrochemical experiments are performed in non-agitated or in non-controlled flow conditions. When such measurements are modelled considering convection, diffusion, migration and reactions, the problem of describing a suitable velocity field arises immediately. Based on the work of Amatore (2001), we present a workable approach that avoids solving the velocity fields in multi-ion modelling. The convection is treated as a diffusion term that becomes dominant from a certain distance from the wall (electrode). This implies that mass transfer becomes irrelevant from that distance on and that there is a fluent transition from the diffusion layer to the bulk of the solution. The theory is elaborated and two examples clearly show the applicability.