The Electrode, Shell Interface
The Electrode, Shell (els) interface (), found under the Electrochemistry branch () when adding a physics interface, models electric current conduction in the tangential direction on a boundary.
The physics interface is suitable for modeling thin electrodes where the potential variation in the normal direction to the electrode is negligible. This assumption allows for the thin electrode domain to be replaced by a partial differential equation formulation on the boundary. In this way the problem size can be reduced, and potential problems with mesh anisotropy in the thin layer can be avoided.
Ohm’s law is used in combination with a charge balance to describe the conduction of currents in the shell electrode.
When this physics interface is added, these default nodes are also added to the Model Builder — Electrode, Electric Insulation (the default edge or point condition), and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, edge or point conditions and current sources. You can also right-click Electrode, Shell to select physics features from the context menu.
Settings
The Label is the default physics interface name.
The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first physics interface in the model) is els.
Thickness
For 2D components, enter a value or expression for the Out-of-plane thickness d (SI unit: m). The default value is 1 m.
Dependent Variables
The dependent variable (field variable) is for the Electric potential. The name can be changed but the names of fields and dependent variables must be unique within a model.
Discretization
To see all settings in this section, click the Show button () and select Advanced Physics Options.
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Theory for the Electrode, Shell Interface
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Boundary, Edge, Point, and Pair Nodes for the Electrode, Shell Interface
In the COMSOL Multiphysics Reference Manual see Table 2-3 for links to common sections and Table 2-4 to common feature nodes. You can also search for information: press F1 to open the Help window or Ctrl+F1 to open the Documentation window.