Modeling Permanent Magnets

Simcenter STAR-CCM+ allows you to model solids and multi-part solid assemblies as permanent magnets.

To model permanent magnets:

Set up the physics continua as described in Selecting the Physics Models and Materials.
Activate the Permanent Magnet model in the relevant solid continua.
From the Permanent Magnet Specification group, activate one of the following models:
- To specify permeability and remanence by matching demagnetization curves, activate the Alpha-Beta Scaling model. See Alpha-Beta Scaling Model Reference.
- To specify permeability and remanence for cases with no temperature dependence, or for simple temperature dependence that can be modeled by general methods such as profiles or field functions, activate the Linear Permanent Magnet General model. See Modeling Permanent Magnets.
If you want to determine when the magnet is at risk of demagnetization, activate the Demagnetization Indication model in the relevant solid continua.
For information on the Demagnetization Indication model, see Demagnetization Indication Model Reference.

For a permanent magnet, you define the magnetic permeability and the remanence flux density, which is the magnetic flux density that exists in the permanent magnet in the absence of external magnetic fields. When you model the demagnetization risk, you also define the knee point flux density, which is the magnetic flux density below which the demagnetization process becomes irreversible.

When the physics continuum associated with the magnet contains a physics model that computes or prescribes the temperature field (for example, the Segregated Solid Energy model or the Specified Temperature model), you can define the material properties of the magnet as functions of temperature.

To define the properties of the permanent magnet:
- To determine the temperature dependence of remanence or permeability with the Alpha-Beta Scaling model, set the following properties under Material Properties > Alpha-Beta Scaling for the solid model of the magnet.
  - Reference Temperature $T_{s}$
  - Alpha Linear $α_{L}$
  - Alpha Quadratic $α_{Q}$
  - Beta Linear $β_{L}$
  - Beta Quadratic $β_{Q}$
  See the B-H curve of the permanent magnet. As the software sets no constraints on these values, make sure they are realistic.
  You can also use this model demagnetization knee point on temperature. For information on the Alpha-Beta Scaling model, see Alpha-Beta Scaling Model Reference.
- To define the properties of the permanent magnet using the Linear Permanent Magnet General model:
  1. Expand the relevant [solid continuum] > Models > Solid > Material Properties node.
  2. Select the Magnetic Permeability node and define the material permeability using either the Constant, Field Function, or Table (T) method.
    For more information, see Material Properties.
  3. Select the Remanence Flux Density node and specify the remanence flux density of the magnet, using either the Constant, Field Function, Table (T), or Polynomial in T method.
If applicable to your simulation, select the Knee Point Flux Density node and define the material knee point flux density using either the Constant, Field Function, or Temperature Adjusted method.
For more information, see Knee Point Flux Density.

For solid materials, you can also store the remanence flux density and the knee point flux density as database properties. The following example is for the remanence flux density, but the same steps apply to the knee point flux density:

Expand the Tools > Material Databases > [Material Database] node.
Right-click the relevant material node and select New Database Properties....
Depending on the chosen method, select either Remanence Flux Density, Remanence Flux Density - Table (T), or Remanence Flux Density - Polynomial, click OK, then set the new property as appropriate.

After setting the remanence flux density, define the magnetization direction, that is, the direction of the remanence flux density of the permanent magnets. You can specify this direction on the physics continuum, so that it applies to all regions associated with the continuum, or you can specify the magnetization direction independently for each region or boundary.

To set the magnetization direction on the physics continuum:

Select the [solid continuum] > Models > Permanent Magnet > Magnetization Direction node and specify the magnetization direction as a unit vector.

To specify a different magnetization direction on specific regions:

Expand the relevant Regions > [solid region] > Physics Conditions node.
Select the Magnetization Direction node and set Method to Specify Region Values.
Select the Physics Values > Magnetization Direction node and specify the magnetization direction for the region.
When using per-part values, you can use a similar procedure to override region values on specific boundaries. See Boundary Settings: Magnetization Direction.