Describing material media
Introduction
The material media are described by using of material regions :
- mainly volume regions in 3D problems; surface regions and line regions are also possible in 3D
- mainly surface regions in 2D problems; line regions and point regions are also possible in 2D
For additional information about the role of the regions, see chapter Physics: principles.
Material regions: overview
Volume, surface or line material regions enable the modeling of the material media. The physical properties of the medium are those of the corresponding material region.
| A region … | enables the modeling … |
|---|---|
| conducting | of a conducting medium (resistivity ρ ) |
| inactive | of an insulating medium |
Thin regions
Thin regions enable the modeling of regions of slight thickness.
In 3D problems for a conducting region, the direction of the electric field can be selected by the user, as indicated in the table below.
| Thin region | Direction of the electric field (and the current) | ||
|---|---|---|---|
| no restriction | quasi normal | quasi tangential | |
| conducting | thin region with random ρ resistivity |
thin region with: ρ2 >> ρ1
|
thin region with: ρ2 << ρ1 |
Filiform regions
The filiform regions enable the modeling of the regions of small cross-section.
In 3D problems for a conducting region, the direction of the electric field is imposed by Flux. The electric field is considered tangent to the line that models the filiform region.