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Corrosion Module

Model Corrosion Processes and Corrosion Protection Systems

Modeling and simulation are powerful tools for understanding corrosion and designing and optimizing corrosion protection systems. The Corrosion Module, an add-on to COMSOL Multiphysics®, enables engineers and scientists to effectively model corrosion processes and protection systems in an intuitive user interface. The modeling process is streamlined by the software's capacity to describe the transport processes in an electrolyte, including the transport of ions and neutral species as well as the balance of current in metal structures. The Corrosion Module also includes capabilities for describing in detail the charge transfer reactions that are responsible for corrosion occurring at electrolyte–metal surfaces.

The module includes a thermodynamic database with electrode potentials and a selection of kinetic expressions for the most common redox reactions at these surfaces. The transport and reaction processes that describe corrosion and corrosion protection systems can be modeled in 1D, 2D, and 3D using the finite element method (FEM) and boundary element method (BEM).

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A foundation with multiple wind turbines showing the electrode potential.
A model of a pit showing the corrosion rate in the Rainbow Light color table with white streamlines.

Corrosion Processes

The Corrosion Module can be used to model a wide variety of corrosion processes, such as galvanic, pitting, crevice, atmospheric, and general corrosion. It can also be used to model sweet and sour corrosion in oil and gas systems, corrosion in reinforced concrete, and corrosion from stray currents.

These corrosion processes stem from similar types of electrochemical phenomena for which the transport and balance of both charge and mass must be considered. The module makes it easy to define relevant boundary conditions, surface reactions, and bulk electrolyte conditions. The electrolyte can be described as a thin layer of moisture, a porous material, or a liquid electrolyte.

With the underlying capabilities of the COMSOL Multiphysics® platform, the Corrosion Module can be combined with other add-on products to model coupled phenomena, such as heat transfer and structural mechanics. This multiphysics modeling functionality is available for phenomena involved in problems like stress corrosion cracking (SCC) and oxide jacking in concrete.

Corrosion Protection Systems

There are many corrosion prevention methods that can be used to help maintain the structural integrity of structures susceptible to corrosion. These include sacrificial anode cathodic protection (SACP), impressed current cathodic protection (ICCP), coating systems, and anodic passivation protection.

COMSOL Multiphysics® and the Corrosion Module can be used to study protection systems and optimize their designs to support many types of structures, such as offshore windmills, subsea oil platforms, and onshore pipelines, plants, and storage tanks. The Corrosion Module can also be used to model road bridges and building infrastructure, water dams and hydropower equipment, and ships, submarines, and harbors. It can also be used to model corrosion processes in the automotive industry.

The Corrosion Module includes specialized functionality for modeling corrosion protection systems at both the microscale and macroscale. This specialized modeling functionality can be used to investigate how pipelines may interfere with the protection systems of other structures, for example. It can also be used to predict the lifetime of a protection system as well as the impacts of anode consumption, stray currents, impressed cathodic currents, and coating degradation.

A ship hull model showing the current density with red streamlines.

Features and Functionality in the Corrosion Module

The Corrosion Module provides specialized tools for streamlining the modeling of various corrosion processes.

A close-up view of the Model Builder with the Tertiary Current Distribution, Nernst-Planck node highlighted and a steel bar model in the Graphics window.

Modeling Galvanic Corrosion

COMSOL Multiphysics® and the Corrosion Module provide ready-made user-friendly interfaces for modeling electrochemistry and corrosion. The basic functionality is provided by user interfaces for primary, secondary, and tertiary current distribution. These interfaces make it possible to model current distribution, surface kinetics with polarization curves, and mass transport effects with bulk equilibrium reactions.

Each of these user interfaces provides a different level of fidelity, allowing the user to select the level needed to give a sufficiently accurate description of the system in mind, whether it requires only ohmic effects or is a more complex model, such as one that includes mass transport and equilibrium reactions for multiple species. COMSOL Multiphysics® enables you to seamlessly add as many species and reactions as required for a given physical system.

A close-up view of the Model Builder with the Current Distribution, Shell node highlighted and a busbar model in the Graphics window.

Modeling Atmospheric Corrosion

When modeling atmospheric corrosion, the electrolyte layer on the metal surface is usually very thin compared to the size of the structure. In such cases, it may be efficient to assume that the current density is uniform across the thin electrolyte layer. Under this assumption, the current distribution on the surface can be estimated without having to discretize the extremely thin electrolyte layer with a volume mesh. This functionality can be found in the Current Distribution, Shell interface, which reduces computational effort significantly compared to a full 3D discretization.

A close-up view of the Model Builder with the Pipe Electrode Surface node highlighted and a pipeline model in the Graphics window.

Modeling Internal Corrosion Protection in Pipes

Modeling cathodic protection inside a pipe can be challenging due to the large aspect ratio between the length and radius. An easy solution is to neglect the radial potential gradient and to solve only for the potential along the pipe. This solution reduces a volume problem to a line problem, which means that the computational load is significantly reduced without sacrificing accuracy.

A close-up view of the Add Material window and a protection system model in the Graphics window.

Material Library

The Corrosion Module includes a built-in material library with more than 270 entries, with equilibrium potentials and polarization data (local current density versus electrode potential) for a number of metals and alloys in different electrolytes.

A close-up view of the Damage settings and an oxide jacking model in the Graphics window.

Extended Multiphysics Analyses

COMSOL Multiphysics® provides functionality for creating arbitrary couplings between different physics interfaces. For example, stress corrosion cracking (SCC) can be modeled by combining a structural mechanics interface with a corrosion interface. Heat transfer effects can also be incorporated into models of highly temperature-sensitive corrosion and corrosion protection processes with multiphysics couplings. Similarly, turbulent and multiphase flow can be modeled in combination with transport of chemical species and corrosion protection.

A close-up view of the Cathodic Protection settings and a jacket structure model in the Graphics window.

Cathodic Protection

The Corrosion Module has a specialized interface for modeling cathodic protection systems. Users can define their own expressions or choose between predefined boundary conditions, such as Butler–Volmer or Tafel equations, or experimental polarization curves representing the kinetics at the surface. Customized features that use familiar terminology make modeling sacrificial anodes and impressed current systems efficient for corrosion and material engineers.

By describing dissolved and deposited species on cathodes and anodes, models can easily account for calcareous deposits and how these change polarization over time. The module can also compute corrosion rates at specific locations. This information can be combined with transport equations to describe mass transport limitations in, for example, closed cavities and porous materials.

A close-up view of the Model Builder with the Electrode Surface node highlighted and a galvanic corrosion model in the Graphics window.

Deforming Geometries Due to Corrosion and Deposition

The Corrosion Module contains predefined multiphysics interfaces for time-dependent modeling of deformations that occur as a result of deposition or dissolution processes in electrochemical cells. This type of modeling can be accomplished by using a deforming geometry, where the velocities of the boundaries are given by the electrochemical reactions.

In addition, the Level Set and Phase Field interfaces are available to model corrosion where the topology of the corroding electrode surface changes as a result of the corrosion processes, such as in sacrificial anode systems.

A close-up view of the Model Builder with the Current Distribution, Boundary Elements node highlighted and oil platforms in the Graphics window.

Computational Methods: FEM and BEM

When solving physics equations on a real 3D geometry, numerical methods require discretization of the model geometry into elements. In addition to the FEM, the Corrosion Module uses the BEM. For example, specialized beam elements in the Current Distribution, Boundary Elements interface can be used to model corrosion in slender structures. BEM modeling in the Corrosion Module offers a well-proven alternative to FEM for solving cathodic protection problems. It also streamlines the modeling process for slender structures and very large electrolyte domains (e.g., the sea).

A close-up view of an app showing the Results window and a monopile model in the Graphics window.

Simulation Applications

The Application Builder can be used to create simulation applications based on any existing model. The simulation engineer can restrict the available inputs and outputs of these apps, providing a customized, intuitive user interface that can be shared with customers and colleagues for many different purposes, including:

  • Automating difficult and repetitive tasks
  • Creating and updating reports
  • Making key model information available to end users in a user-friendly interface

By focusing on the input parameters and computational results that matter, simulation apps allow R&D experts to engage more effectively with project stakeholders, helping to create a competitive edge.

The Cathodic Protection Designer app included in the Application Library is an example of how simulation apps can be used for cathodic protection design.

Every business and every simulation need is different.

In order to fully evaluate whether or not the COMSOL Multiphysics® software will meet your requirements, you need to contact us. By talking to one of our sales representatives, you will get personalized recommendations and fully documented examples to help you get the most out of your evaluation and guide you to choose the best license option to suit your needs.

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