Excitation Coil Model Reference

In finite volume simulations, the Excitation Coil model allows you to model the electric current density that is produced by an excitation coil in solid materials.

For finite element simulations, see Finite Element Excitation Coil Model Reference.

Simcenter STAR-CCM+ calculates the coil electric current density from Eqn. (4332) and adds it as a source term in the magnetic vector potential equation Eqn. (4241). Simcenter STAR-CCM+ also calculates the specific magnetic flux linkage according to Eqn. (4341).

In transient simulations, the Excitation Coil model also computes the specific electromotive force.


Model Name	Excitation Coil
Theory	See Excitation Coils.
Provided By	[physics continuum] > Models > Optional Models
Example Node Path	Continua > Physics 1 > Models > Excitation Coil
Requires	Physics Models: Space: one of Two Dimensional, Axisymmetric, Three Dimensional Time: either Steady or Implicit Unsteady Material: one of Solid, Multi-Component Solid > Multi-Part Solid- Optional Models: Electromagnetism Electromagnetism: one of the magnetic potential models When using harmonic balance models, the Excitation Coil model always requires the Eddy Current Suppression model. When using the other magnetic potential models, the Eddy Current Suppression model is only required in transient simulations.
Activates	Region Inputs	Electric Current Density Magnitude, Excitation Coil Resistance Option, Excitation Coil Reference Cross Section, Local Direction Field. See Region Settings.
	Report Options	Excitation Coil Conductor Resistance, Magnetic Flux Linkage. See Reports.
	Field Functions	Specific Electromotive Force, Specific Magnetic Flux Linkage, Local Direction Field. See Field Functions.

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

J_{coil}

(see Eqn. (4332)).

Simcenter STAR-CCM+ calculates the cross-section of the coil,

a_{0}

, with respect to a specified reference area,

a_{ref}

, which can be the actual cross section, or the area that is obtained by cutting the coil with an arbitrary section (see Eqn. (4337)).

To set the quantities in Eqn. (4337), you use the following child nodes:

Ampere Turn: specifies the number of turns $n_{t}$ of the coil that cut though the coil region. When the reference area is equal to the actual cross section of the coil, $n_{s} = 1$ .
- Electric Current: 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.

In three-dimensional analyses, the magnitude of the electric current density is calculated with respect to the reference area specified in the Excitation Coil Reference Cross Section node. In two-dimensional simulations that use the Transverse Magnetic Potential model, the magnitude of the electric current density is calculated with respect to the 2D region area, which is computed automatically.

Excitation Coil Conductor Area

In three-dimensional situations, you specify the area covered by the conducting material. Set Specify by Part Subgroup to Off (the default) for Current-driven, Stranded coils. Set it to On for Current-driven, Solid coils and define individual coils; see Applying Quantities by Subgroup.

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)).

Excitation Coil Number of Sections

In three-dimensional situations, you specify the number of sections

n_{s}

that cut though the coil region. When the reference area is equal to the actual cross section of the coil,

n_{s} = 1

. Set Specify by Part Subgroup to Off (the default) for Current-driven, Stranded coils. Set it to On for Current-driven, Solid coils and define individual coils; see Applying Quantities by Subgroup.

Excitation Coil Reference Cross Section

In three-dimensional simulations, you specify the reference area

a_{ref}

(see Eqn. (4337)) by selecting an appropriate reference part. The reference part can be an internal interface boundary or one of the following derived parts that cuts through the coil region:

plane section
constrained plane section
cylinder section
arbitrary section

Excitation Coil Reference Height

In two-dimensional simulations that use the Transverse Magnetic Potential model, the cross section

a_{0}

is the area of the 2D domain. You define the volume over which the specific magnetic flux linkage is integrated by specifying a reference height for the 2D region.

Local Direction Field

Sets the direction field

f

in Eqn. (4337).

In three-dimensional analyses, the available properties are:

Method: specifies the method for the definition of $f$ . The Part Curve method allows you to define the field orientation using a closed loop. Local Direction Field > Part Curve properties:
- Curve Parts: allows you to select the part curves that represent the local field orientation. Select a closed loop or a curve that extends to the ends of the simulation domain. Selecting all part curves in the coil does not give a correct representation.
- Representation: allows you to choose between the available geometry and mesh representations.
- Direction: sets the current flow direction to either Forward or Backward. This setting is relative to the orientation of the specified part curve.

In two-dimensional analyses that use the Transverse Magnetic Potential model, the Local Direction Field lies along the Z-axis. Specify the sign by setting the Direction property to the appropriate value, Go (current flowing in the +Z direction), or Return (current flowing in the -Z direction).

Reports

Excitation Coil Conductor Resistance: Evaluates the direct current resistance of the excitation coil region (see Eqn. (4343)).; 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. If you use the Excitation Coil model with the Finite Element Magnetic Vector Potential model, do not use this report. In this case, activate the Excitation Coil Lumped Parameter model and use the Regularized Magnetic Flux Linkage report. For more information see Modeling Excitation Coils

Field Functions

Specific Electromotive Force: Corresponds to the specific electromotive force $ρ_{ϵ}$ defined in Eqn. (4342).
Specific Magnetic Flux Linkage: Corresponds to the specific magnetic flux linkage $ρ_{ψ}$ defined in Eqn. (4341).
Local Direction Field: Corresponds to the local direction field $f$ defined in Eqn. (4337) and Eqn. (4336).