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Introduction: Theory, Equations, and Interfaces

In Part 1 of this course on corrosion modeling using COMSOL Multiphysics^® and the Corrosion Module, we begin by introducing the the two main branches of modeling corrosion. These are the corrosion process and corrosion protection systems. The corrosion process focuses on galvanic corrosion mechanisms such as pitting, crevice, atmospheric and stress-induced corrosion. Corrosion protection systems involve cathodic protection (impressed current or sacrificial anodes), anodic protection, and internal pipeline protection. Both branches share the same governing equations. This includes mass, charge and current conservation, and electrochemical reactions occurring at electrolyte-metal interfaces. With the Corrosion Module, there are a variety of physics interfaces in the software that can be used to model corrosion applications, such as, primary, secondary and tertiary current distribution, and their associated losses, which can be coupled with fluid flow, heat transfer, and other physics depending on your model. Current distribution, along with Faradays law, is an important factor in determining corrosion, electrodeposition, and electrochemistry. We also cover some important conventions to keep in mind while modeling corrosion, such as current direction, overpotential, and electrochemical stoichiometry, as well as the major factors that affect the size and computation time of your simulation.

The wire electrode tutorial model is used here to demonstrate how to build a corrosion model step-by-step. Starting with importing the geometry, to coupling multiphysics with laminar flow and species transport to study the primary, secondary and tertiary current density distributions of an electrochemical cell.