Using Tabular Data

The tabular data method is used to provide values of a material property. The multi-dimensional bilinear interpolation method is used for interpolating between data points in the table.

By default, a linear-piecewise interpolation method is used for interpolating between data points in the table. If the point lies outside the table range, the function value is computed at the nearest data point in the table. The properties for this function are set in the Properties window.

As an example, the tabular data method is described here for the magnetic permeability material property of the Magnetic Vector Potential model.

If you want to select the B-H-mu table that is in the material database, you use the Table(B,H) method. The tabular data method does not let you select the permeability table from the material database.

The tabular data method works as follows:

• Select the Tabular > Table node and, in the Properties window, select the table containing the material property data.
  
  
• Select the Table > Interpolated node and, in the Properties window, set the Column title that matches the material property to be returned by the method.
• Select the input quantity against which the material property is interpolated:

  • Right-click the Table > Variables node and choose New.

    A new Variable child node is added.

  • Select the newly added child node. In the Properties window, set the Scalar Function property to the desired quantity. Set the Column title property to the table column that contains values of this quantity.

Setting Magnetic Permeability Property

Following the above procedure, first set the Input table property to the B-H table. The B-H table usually includes three columns: one for the magnetic flux density $\mathbf{\text{B}}$ , one for the magnetic field $\mathbf{\text{H}}$ and one for the calculated permeability $\mu$ that is determined through the relation $\mu =\mathbf{\text{B/H}}$ . An example table is shown below. Only two columns are needed for the tabular data method. For this case, either $\mathbf{\text{H-}}\mu$ or $\mathbf{\text{B-}}\mu$ is used.

Columns that are extracted from this table appear in the Columns property of the Table node.

Having selected the table, choose the mu[H/m] column for the Column title property of the Interpolated child node. This column matches the Magnetic Permeability material property for which the Tabular method has been selected.

Finally, choose either the $\mathbf{\text{H}}$ or $\mathbf{\text{B}}$ scalar field function against which permeability is interpolated. Determining which of these variables to use as the interpolation variable has a direct effect on the convergence of the magnetic vector potential solution (as discussed in the troubleshooting section of electromagnetism modeling).

Here, create a variable and set its Scalar Function property to Magnetic Field: Magnitude, and its Column title property to H[A/m].