Electrochemical Reaction Model Reference

You can use the Electrochemical Reactions model to simulate electrochemical surface reactions that occur during a wide range of electrochemical applications, including:

Galvanic Corrosion
Cathodic Protection
Electroplating
Wet Etching
Fuel Cells
Paint Delamination
Metal-Liquid Interface Reactions

There are two variants of the Electrochemical Reactions model which you can use depending on what you are modeling.

Modeling electrochemical surface reactions without species requires the following models:
- Electrodynamic Potential model
- Electrochemical Reactions model
When using this option, the Electrochemical Reactions model computes an electric current and electric current derivative from the electrochemical reactions that you define, and passes the information to the Electrodynamic Potential model.

Use this option when you want to model the secondary current distribution and ignore the effect of species concentrations.
Modeling electrochemical surface reactions with species requires the following models:
- Electrodynamic Potential model
- Electrochemical Reactions model
- Electrochemical Species model or Charged Species Effects model
When using this option, the Electrochemical Reactions model computes contributions to the electric current from:
- species concentrations
- electrochemical species flux / charged species flux
- flux derivatives
The electric current is passed to the Electrodynamic Potential model, then the species flux and flux derivatives are passed to the Electrochemical Species model or Charged Species Effects model.

Use this option when you want to model electrochemical surface reactions which take into account the species flux due to electrochemical species or charged species concentrations.

Note	The Electrochemical Reactions model only considers concentrations of species components which physically exist in the fluid domains. The concentrations of species that are defined within solid physics models are not considered in rate computations.

Table 1. Electrochemical Reaction Model Reference
Theory	See Electrochemical Surface Reactions (Heterogeneous).
Provided By	[physics continuum] > Models > Electrochemistry
Example Node Path	Continua > Physics 1 > Models > Electrochemical Reactions
Requires	Space: any Material: any except Multi-Component Solid Optional Models: Electrochemistry
Properties	None.
Activates	Physics Models	Flow
	Model Controls (child nodes)	In fluid physics continua: Surface Mechanism Manager, [Surface Mechanism]
	Region Inputs	Secondary Current Phase Interaction Option. See Electrochemical Reaction Model Region Settings.
	Boundary Inputs	Electrochemistry Mechanism Option. See Electrochemical Reaction Model Boundary Settings.
	Interface Inputs	Electrochemistry Mechanism Option. See Electrochemical Reaction Model Interface Settings.
	Field Functions	Electrochemical Surface Overpotential, Electrochemical Reaction Rate, Electrochemical Equilibrium Potential, Boundary Species Electrochemical Reaction Flux, Bulk Species Electrochemical Reaction Flux. See Field Functions.
	Porous Phase Models	When selected in the same continuum as the Porous Media model, provides the Phase Reacting Model for each porous phase. See Phase Reacting Model.

Electrochemical Reaction Model Region Settings

Fluid Regions—Physics Conditions

Electrochemistry Mechanism Option

Mechanism	Corresponding Physics Value Nodes
None	None
[Electrochemical Mechanism]	Electrode Electric Potential Set the electric potential of the electrode as a scalar profile.

Secondary Current Phase Interaction Option

Available when modeling secondary current distribution type reactions. See Secondary Current Distribution. Allows you to specify the Electrolyte Phase and the Solid Phase which Simcenter STAR-CCM+ requires to correctly apply the equilibrium electric potential jump at the interface.

Fluid Regions—Physics Values

Electrochemical Resistance: When modeling electrochemical surface reactions without defining electrochemical species, and the electrochemical surface mechanism is set at the region level, you can specify the electrochemical resistance as a physics value for the region.
Phase Interaction Area: Allows you to specify the interaction area density for the reactions in the specified phase interaction.

Electrochemical Reaction Model Boundary Settings

Any Boundary Type

Electrochemistry Mechanism Option

Mechanism	Corresponding Physics Value Nodes
None	None
[Electrochemical Mechanism]	Electrode Electric Potential Set the electric potential of the electrode as a scalar profile.

Electrochemical Reaction Model Interface Settings

Interfaces between Solid and Fluid, or Solid and Porous, Regions

Electrochemistry Mechanism Option

Mechanism	Corresponding Physics Value Nodes
None	None
[Electrochemical Mechanism]	Electrode Electric Potential Set the electric potential of the electrode as a scalar profile.

Field Functions

Electrochemical Surface Overpotential

Displays the electrochemical surface overpotential

η

in Eqn. (4122).

Electrochemical Reaction Rate

Displays the electrochemical reaction rate (specific reaction current density),

j_{n, s}

, in:

Eqn. (4129) when using the Butler Volmer reaction method
Eqn. (4132) when using the Tafel reaction method
Eqn. (4134) when using the Tafel Slope (log 10) reaction method
Eqn. (4136) when using the Transport Limited Tafel Slope (log 10) reaction method

Electrochemical Equilibrium Potential

Displays the electrochemical equilibrium potential

U_{e q}

in Eqn. (4122) and Eqn. (4139).

Boundary Species Electrochemical Reaction Flux

Available when using both the Electrochemical Reactions model and the Electrochemical Species model. Shows the reaction flux,

N_{i}

, in [kmol/m²s] for all electrochemical species and the solid species that are registered for the specific electrochemical reaction mechanism.

Surface Mechanism Manager

Right-Click Actions

New Surface Mechanism: Creates the SurfaceMechanism subnode which allows you to specify details of that electrochemical surface mechanism. You can create more than one electrochemical surface mechanism. See SurfaceMechanism.
Remove Invalid Surface Mechanisms: Allows you to remove electrochemical surface mechanisms which are invalid ().

[surface mechanism]

If the electrochemical surface mechanism appears with a caution symbol (

), it is invalid. For example, when the Electrochemical Species model is selected and the electrochemical surface mechanism is defined, the Reaction [n] Type is set to Electrochemical Species. Deselecting the Electrochemical Species model maintains the reaction type and marks the electrochemical surface mechanism as invalid. You can then create an electrochemical surface mechanism which is valid and either; keep the invalid electrochemical surface mechanism to use again (when reverting to the previous model selections), or remove the invalid electrochemical surface mechanism. Invalid electrochemical surface mechanisms cannot be selected for use on boundaries or interfaces. If electrochemical surface mechanisms that contain electrochemical species become invalid, the electrochemical species are removed from the electrochemical surface mechanism and must be re-selected if the electrochemical surface mechanism then becomes valid again.

Right-Click Actions

Import Species: Displays the Select file and material database dialog. The dialog allows you to select a file that contains the required species, and specify the Material Database to which the species are added.
Import Species and Reactions: Displays the Select file and material database dialog. The dialog allows you to select a file that contains the required species and reaction mechanisms, and specify the Material Database to which the species are added.
Dependencies: Opens the Dependencies dialog that lets you find out which interfaces, regions, or boundaries use the surface mechanism. This option is useful, for example, if you want to delete the [surface mechanism] node. Before you can delete the [surface mechanism] node, you must deselect the electrochemical mechanism from the location where it is applied.

Phase Reacting Model

Selected automatically (and not de-selectable) for porous phases within continua that contain the Electrochemical Reactions model. This model has no properties or settings to specify—it allows electrochemical reactions within the porous phase.