Home / Examples / Electric Analysis [Coulomb] / Example 12: Periodic Boundary Condition

Example 12: Periodic Boundary Condition

General

• The basic unit of capacitors, consisting of alumina blocks and electrodes, are periodically placed in the analysis space.
   

• By applying periodic boundary conditions, the analysis area can be minimized.
   

• The distributions of electric field and electric potential are solved.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')




• Results will vary depending on Femtet version and the PC environment.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

Analysis Conditions

Select "Static analysis" as the electric potential is static.

Item	Settings
Solver	Electric Analysis [Coulomb]
Analysis Type	Static Analysis (Capacitance)
Mesh/Meshing Control	Select Use Mesher G1 *
Options	N/A

*As the default setting of Mesher G2 can not handle the periodic boundary condition for more than one pair, Mesher G1 is applied.

 

 

Disable automatic creation of the air domain.

Tab	Setting Item	Settings
Mesh Tab	Automatic Air Domain Creation	Create air domain automatically: Deselect

Model

The base unit of the periodic structure is modeled.

 

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Solid	Air	000_Air(*)
2/Solid	Block	001_Alumina *
3/Solid	Block	001_Alumina *

* Available from the material DB

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
V1/Face	Electric	Electric Wall	Electric Potential Specified 1 [V]
V2/Face	Electric	Electric Wall	Electric Potential Specified 0 [V]
Periodical1	Symmetry/Continuity		Periodic
Periodical2	Symmetry/Continuity		Periodic
Periodical3	Symmetry/Continuity		Periodic
Periodical4	Symmetry/Continuity		Periodic

 

On the [Model] tab,

 

 

click [Boundary Pair] and complete the pairing as follows.

 

 

List of Pairs

Periodical1 - Periodical2

Periodical3 - Periodical4

Results

The vectors of the electric field are shown below.

 

The isoline contour of the electric potential is shown below.

The paired faces of the periodic boundary conditions have the same values,

which proves that the solution is correct.

 

For comparison, the potential is calculated under the magnetic wall boundary condition.

The resulting isoline contour is shown below.