COMSOL 6.2 - Infinite Element Domain

An node (

) applies a real-valued coordinate scaling to a layer of virtual domains surrounding the physical region of interest. When the dependent variables vary slowly with radial distance from the center of the physical domain, the finite elements can be stretched in the radial direction such that boundary conditions on the outside of the infinite element layer are effectively applied at a very large distance from any region of interest.

To add an Infinite Element Domain to any Component, click in the toolbar, or right-click the node under the Component and choose . If the nodes under the node are grouped by type, you can instead right-click

under .

Settings

The is the default infinite element domain name.

The default (for the first infinite element domain in the model) is ie. The provides a namespace for variables created by the node. For example, the scaled x coordinate can typically be accessed in equations and postprocessing as ie1.x. See the subnode for a complete list of available variables.


	To display the Equation View node under all nodes creating variables, click the Show More Options button () and select Equation View in the Show More Options dialog box. See also Equation View.

Domain Selection

Select a set of domains conforming to the selected geometry type. See Standard Geometry Configurations.

Geometry

Select a : (the default), , , or .

•

If is selected, enter the position of the center of the spherical geometry in the table. For axisymmetric models, only the z coordinate is required since the geometry must be centered on the axis.

•

If is selected, enter the position of a point on the cylinder axis in the table. For 3D models, also enter a vector.

•

If is selected, first choose the appropriate for the geometrical configuration. Then for each stretching direction specify a , evaluating to the distance from the inner boundary of the infinite element domain measured in the stretching direction, and the of the domain in the same direction.


	Each of these types (except the user-defined type) requires certain geometrical configurations and not all of them are available for all space dimensions.

Scaling

Select a : (the default) or . See Infinite Element Implementation for a detailed explanation of the options.

For the default stretching type, enter expressions for the (SI unit: m) and the (SI unit: m). The default values, 1e3*dGeomChar and dGeomChar, respectively, lead to an infinite element domain that is very large compared to the geometry dimensions and with a nearly singular 1/r stretching.

For the stretching type, select a from functions defined under or under in a component, or leave the default value , which is interpreted as f(ξ) = ξ. Any function node defining a single function of one arguments is eligible for use as a stretching function. The argument is interpreted as a dimensionless distance, ξ, in the range 0 to 1.


	If you have the AC/DC Module, see this example: Modeling of a 3D Inductor: Application Library path ACDC_Module/Devices,_Inductive/inductor_3d


	If you have the Battery Design Module, Corrosion Module, Electrochemistry Module, Electrodeposition Module, or Fuel Cell & Electrolyzer Module see this example: Voltammetry at a Microdisk Electrode: Application Library path Battery_Design_Module/General_Electrochemistry/microdisk_voltammetry, Corrosion_Module/General_Electrochemistry/microdisk_voltammetry, Electrochemistry_Module/Electroanalysis/microdisk_voltammetry, Electrodeposition_Module/Tutorials/microdisk_voltammetry, Fuel_Cell_and_Electrolyzer_Module/General_Electrochemistry/microdisk_voltammetry