Corrosion Module Updates

For users of the Corrosion Module, COMSOL Multiphysics® version 5.6 brings a new Corrosion material library, a Phase Field interface to model electrode deformations, and automatic generation of iterative solvers. Learn more about the corrosion updates below.

Automatic Generation of Iterative Solvers

The Iterative Geometric and Algebraic Multigrid solvers are now automatically generated by the study step nodes (however, a Direct solver will still always be used by default). Enabling one of the iterative solvers may decrease memory use and computational time for large simulations.

Linearization of Concentration Dependence in Electrode Kinetics

The new Linearization option improves kinetics for nonunit reaction orders by circumventing issues when evaluating powers of negative numbers. This feature is available in the Electrode Reaction and Porous Electrode Reaction nodes in the Tertiary Current Distribution interfaces when using the Nernst equation for the equilibrium potential in combination with either the Mass action law or Lumped multistep for the exchange current density. The new Linearization option is turned on by default when creating a new model and is used by all tutorial models featuring the Nernst equation and mass action law or lumped multistep kinetics options.

A closeup view of the COMSOL Multiphysics version 5.6 UI showing the settings for the Electrode Reaction node with the Electrode Kinetics section expanded.
User interface of the Electrode Reaction node for defining electrode kinetics.

New Corrosion Material Library

The new Corrosion material library contains more than 270 entries of polarization data from scientific literature. The following tutorial models have been updated to use in the new Corrosion material library:

Highly Conductive Porous Electrode

The new Highly Conductive Porous Electrode domain node is available in most electrochemistry interfaces. This feature can be used for porous electrodes with a high conductivity in the electron-conducting electrode phase. It replaces the spatial variable for the electrode potential by a global variable, thereby reducing the number of degrees of freedom of the problem. You can see this new feature in the Crevice Corrosion in Iron in an Acetic Acid/Sodium Acetate Solution tutorial model.

A 1D plot of the solution composition at 0.844 V from a crevice corrosion model.
The Crevice Corrosion in Iron in an Acetic Acid/Sodium Acetate Solution tutorial model makes use of the new Highly Conductive Porous Electrode node.

New Porous Medium Feature

A new feature for handling a porous medium is available for defining the different phases: solids, fluids, and immobile fluids. In the Heat Transfer in Porous Media interface, the Porous Medium feature is used to manage the material structure with a dedicated subfeature for each phase: Fluid, Porous Matrix, and optionally, Immobile Fluids. This new workflow provides added clarity and improves the user experience. It also facilitates multiphysics couplings in porous media in a more natural way. Combined with the Moisture Transport and Porous Media Flow interfaces, the heat transfer in porous media improvements enable the modeling of nonisothermal flow and latent heat storage in porous media.

You can see this new setup in the following models:

Revamped Porous Media Features for Transport of Diluted Species

The Transport of Diluted Species in Porous Media interface is revamped to use the new Porous Medium node. Two new domain features, the Porous Medium and the Unsaturated Porous Medium nodes, are available in the Transport of Diluted Species in Porous Media interface. You can use the new Porous Medium node for assigning material properties to the multiple phases in a porous medium. The new nodes have dedicated containers to define the properties for the liquid, gas, and porous matrix. You can see this functionality demonstrated in the Ceramic Water Filter with Activated Carbon Core tutorial model.

A closeup view of the COMSOL Multiphysics version 5.6 UI with the settings shown for Transport of Diluted Species in Porous Media and a ceramic water filter candle model in the Graphics window.
Contaminant concentration in a ceramic water filter candle.

Phase Field Interface

The Phase Field interface has been added to the Corrosion Module. This interface may be used to model electrode and metal surface deformations where the topology of these surfaces changes as a result of the dissolution/deposition of material. You can see this feature in the new Localized Corrosion Using the Phase Field Method tutorial model.

Easier Setup for Phase Field and Level Set Models

The Level Set and Phase Field interfaces have been restructured: Two Initial Values nodes are now added by default, and the previously used Initial Interface feature has been removed. Instead, the initial interface is automatically placed at the boundaries between the two Initial Values nodes with different initial phases.

Settings for the Initial Values, Fluid 2 feature. Note that the Initial Interface feature is no longer needed. The initial distribution of the level set or phase field function is solved for in the Phase Initialization study step.

New Tutorial Model

COMSOL Multiphysics® version 5.6 brings one new tutorial model to the Corrosion Module.