COMSOL 6.4 - Materials

Ideally, the metal is an equipotential body and the electric field inside the metal is zero. Usually, the metal parts are excluded from the computation domain since their potential is known in advance. One can also include the metal parts and define the potential using the Domain Terminal feature. In this case, the domain of the metal parts is not solved and thus it is not necessary to assign a material to it. For other domains, the relative permittivity of the material needs to be defined, as listed below.


Material	Relative permittivity
Core rod	5
Weather shed	3
Air	1

1

In the Model Builder window, under Component 1 (comp1) right-click Materials and choose Blank Material.

2

In the Settings window for Material, type in the Label text field.

3

Select Domains 3–5 only. An easy way to do this, is to first clear the selection and then manually select domains 3–5 (the Core Rod). Alternatively clear the selection, choose the “Paste Selection” option, and type “3, 4, 5” in the Paste Selection dialog.

4

Locate the Material Contents section. In the table, set the value of relative permittivity to 5.

The Settings of the Core Rod material are shown in the figure to the right. Next, add similar settings for other materials.

1

Right-click Materials and choose Blank Material.

2

In the Settings window for Material, type Weather Shed in the Label text field.

3

Select Domain 7 only.

4

Locate the Material Contents section. In the table, set the value of relative permittivity to 3.

For the air, the default Free Space properties will suffice. It is therefore not necessary to add the material properties explicitly.