Finite Element Excitation Coil Model Reference

In Simcenter STAR-CCM+, you model an excitation coil as a solid region. The Finite Element Excitation Coil model calculates the electric current density produced by the excitation coil from Eqn. (4332) and adds it as a source term in the magnetic vector potential equation (Eqn. (4301)).

Properties

Method

The method that is used to specify the current direction.

Boundary

Defines the current direction as specified in the Electric Current Direction boundary setting.

Vector

Sets the current direction to the surface normal of a reference plane that crosses the coil. This method is intended for closed coils, for which inflow/outflow boundaries do not exist.

Boundary Settings

Electric Current Direction

Defines the direction of the electric current flow at the boundary.

• Insulating: the boundary is an insulator, that is, there is no electric current flow across the boundary (see Eqn. (4335)).
• Inflow, Outflow: electric current flows across the boundary (see Eqn. (4335)). When the local direction is Forward (see Local Direction Field), electric current flows from the Outflow boundary to the Inflow boundary. When the direction is Backward, the current direction is reversed.

Region Settings

Applies to solid regions.

Excitation Coil Resistance Option

Available when you activate one of the excitation coil models or when you create an excitation coil circuit element. Allows you to specify the resistance of the excitation coil region. You can specify the resistance value directly or instruct Simcenter STAR-CCM+ to calculate it automatically.

Method	Corresponding Physics Value Nodes
Automatic The default. Simcenter STAR-CCM+ calculates the coil resistance automatically from its conductivity, length, and cross-section area.	None
None Sets coil resistance to zero.	None
Specified Allows you to specify coil resistance as a scalar.	Excitation Coil Resistance Coil resistance, in ohms, specified in the Value property.

Electric Current Density Magnitude

Specifies the parameters that Simcenter STAR-CCM+ uses to calculate ${\mathbf{\text{J}}}_{\mathrm{coil}}$ (see Eqn. (4332)):

• Ampere Turn: specifies the number of coil turns $n_t$ in Eqn. (4335). When the coil region comprises multiple coil parts, the number of turns is the total number of turns in a single part (and not the number of turns in the entire region).
  • Electric Current (for the Finite Element Magnetic Vector Potential model): specifies the electric current $I$ that goes though an individual wire as a scalar profile. Together with the common methods for setting scalar profiles, Simcenter STAR-CCM+ provides an additional method called Circuit Element. This method allows you to select a circuit element and use the current through this element as the input for the electric current inside the excitation coil.
  • Complex Electric Current (for the Harmonic Balance FE Magnetic Vector Potential model): specifies the electric current ${\mathrm{J}}_{\mathrm{e}\mathrm{x}}$ that goes though an individual wire as a complex profile. See Eqn. (4260) and Eqn. (4261).
  • Conductor Area: specifies the area that is covered by conducting material. You can enter an absolute value or a relative value (a percentage of the total coil area). Simcenter STAR-CCM+ uses the specified value to calculate the direct current resistance of the coil (see Eqn. (4343)).

Local Direction Field

Factor that determines the direction of the current flow. The available properties are:

• Specify by Part Subgroup: Allows you to set the direction field independently on each part that is assigned to the coil region. Requires you to activate the property Allow Per-Part Values on the corresponding region.
• Direction: for Original direction (inflow to outflow, $s=1$ in Eqn. (4335)), the current flows from the Outflow boundary to the Inflow boundary (see Electric Current Direction). When the direction is Flipped (outflow to inflow, $s=-1$ in Eqn. (4335)), the current direction is reversed.

Reports

Excitation Coil Conductor Resistance

Evaluates the direct current resistance of the excitation coil region.

When you create this report, specify the regions that you want to include in the report. If you define a coil region using part sub-grouping, make sure each sub-group in the region has an identical Electric Current defined under the Electrical Current Density Magnitude > By Part Subgroup > [Subgroup] > Ampere Turn node.

Magnetic Flux Linkage

Reports the flux linkage through the selected coil parts or regions. If you select an excitation coil circuit element, its assigned regions are included in the flux linkage evaluation. In general, this is the preferred report for calculating the magnetic flux linkage. However, if you select the Excitation Coil model instead of the Finite Element Excitation Coil model, also activate the Excitation Coil Lumped Parameter model and use the Regularized Magnetic Flux Linkage report instead. For more information see Excitation Coil Lumped Parameter Model.

Field Functions

Local Direction Field

Direction field that represents the direction of the electric current flow.

Slot Fill Factor

Gives the ratio of excitation coil cross-section to the total area. The Excitation Coil Conductor Area physics value defaults to Relative.

Unlike the finite volume Excitation Coil model, the Finite Element Excitation Coil model does not provide the Specific Electromotive Force and Specific Magnetic Flux Linkage field functions. For additional field functions and reports, you can activate the Finite Element Excitation Coil model in conjuction with the Excitation Coil Lumped Parameter model (see Excitation Coil Lumped Parameter Model Reference).