Computer simulation of a single pit in CO₂ corrosion in the presence of acetic acid

In our recent work, we have shown, using artificial pit electrode, that acetic acid (HAc) has a major effect on the propagation stage of localized attacks in CO₂ corrosion. Since then a numerical simulation of steady state pitting concision has been developed to overcome the system complexity and analyze underlying mechanisms. The model consisted of a 2D axis-symmetric pit in static dilute solution under similar working conditions given in Ref. 1. Transport-reactive phenomena are governed by Nernst-Planck law with electroneutrality assumption. Both cathodic and anodic processes are simply described by Butler-Volmer relationships fitted to the experimental data. The present paper focuses on giving further information about species and current distributions as well as potential drop profiles along the pit depth. Particular attention is paid to the effect of HAc concentration on the coupling mechanism between the pit and the outer surface.