The Curvilinear Coordinates Interface

With the Curvilinear Coordinates interface, you can create a vector field v and a base vector system (with basis vectors e1, e2, and e3) that can be used by other physics to specify, for example, external currents or anisotropic material properties of a bundle of wires or fibers. The resulting coordinate system can be — but does not have to be — curvilinear. Right-click the Curvilinear Coordinates node () to add one of the available methods for computing the vector field for the curvilinear coordinates:

•	Diffusion Method

•	Adaptive Method

•	Elasticity Method

•	Flow Method

•	User Defined

The first node added will be applied to all domains by default. Additional nodes will have an initially empty selection. You can use more than one vector field computation method (of the same or different types), by applying the corresponding nodes on different sets of domains.

The Curvilinear Coordinates interface is available for 2D, 2D axisymmetric, and 3D geometries. The Settings window contains the following sections:

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 Curvilinear Coordinates interface in the model) is cc.

Equation

See Physics Nodes — Equation Section.

Settings

The Normalize vector field check box is selected by default because a normalized vector field simplifies the use of curvilinear coordinates and a base vector system.

Select the Create base vector system check box to add a Curvilinear System node under Definitions, which is a Base Vector System node with a name that indicates that it is created by a Curvilinear Coordinates interface and contains the base vectors from the curvilinear coordinate computation. Selecting this check box also adds a Coordinate System Settings subnode for specifying the second basis vector e2 (the software then forms the third basis vector as the cross product of the first and second basis vectors).

Working with Geometric Entities

Anisotropic Heat Transfer through Woven Carbon Fibers: Application Library path COMSOL_Multiphysics/Heat_Transfer/carbon_fibers