The Electric Currents, Layered Shell (ecls) interface (), found under the AC/DC branch () when adding a physics interface, is used to compute electric fields, currents, and potential distributions in thin conducting layered shells under conditions where inductive effects are negligible; that is, when the skin depth is much larger than the studied device. It supports stationary modeling on faces in 3D.

The physics interface solves a current conservation equation based on Ohm’s law using the scalar electric potential as the dependent variable. The electric potential is added either by the Layered Shell feature or the Homogenized Shell feature. Both features have advantages and disadvantages, particularly considering shell thickness and electrical connections between the shells.

For (moderately) thick shells, the layered shell implementation is superior as it provides a full 3D representation (perpendicular potential gradients and -currents are included by means of an extra dimension). The homogenized shell implementation instead only solves for in-plane potential gradients. It requires less degrees of freedom, and is numerically more stable. It is especially useful for very thin layers, for which the layered shell implementation may fail. Moreover, it naturally preserves electrical continuity across edges interior to the shell. Both the Layered Shell feature and the Homogenized Shell feature are equipped with a number of subfeatures, allowing you to take advantage of the strength of each, in different parts of the model.

When the physics interface is added, the following default nodes are added to the Model Builder— Layered Shell and Electric Insulation (the default edge condition). Then, from the Physics toolbar, other nodes can be added that implement, for example, boundary or edge conditions and interlayer connections. You can also right-click Electric Currents, Layered Shell to select physics features from the context menu.

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 ecls.

Select the applicable layers (the default setting is All layered materials). If no layered materials have been included yet, there is a shorthand available for creating a Single Layer Material (the plus, next to the Layer Selection setting).

The dependent variable (field variable) is for the Electric potential V. The name can be changed but the names of fields and dependent variables must be unique within a model. This variable is explicitly used only by Homogenized Shell features. The Layered Shell features have their own variable name (for the degrees of freedom in the extra dimension).

The setting for the discretization order is shared by the Homogenized Shell degrees of freedom and the Layered Shell degrees of freedom.