Home / Examples / Electric Analysis [Coulomb] / Example 1: Parallel-Plate Air-Gap Capacitor

Example 1: Parallel-Plate Air-Gap Capacitor

General

• The capacitor analyzed in this example consists of two parallel conductive plates which have the electric potential difference.
   

• The capacitance, the electric field, and the equipotential map 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)
Options	N/A

 

In actuality, the electric field exists outside the analysis domain. Therefore the open boundary condition below is applied initially.

Tab	Setting Item	Settings
Open Boundary Tab	Type	Absorbing Boundary
	Order of Absorbing Boundary	1st-order

Model

Create 2 sheet bodies for electrodes. Then, specify the electric potential on each as boundary condition.

Body Attributes and Materials

Two sheet bodies are used to imprint the electric potential-specified boundary condition.

They are called "imprinting body".

You don't need to set the body attribute or the material property on them.

Body Number/Type	Body Attribute Name	Material Name
1/Sheet	Imprinting body
2/Sheet	Imprinting body

* Available from the material DB

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Electrode1/Face	Electric	Electric Wall	Electric Potential Specified -1 [V]
Electrode2/Face	Electric	Electric Wall	Electric Potential Specified +1 [V]
Outer Boundary Condition *	Electric	Open Boundary

 

To set Outer Boundary Condition, go to the [Model] tab
 

 

and click [Outer Boundary Condition] .

Results

To see the calculation results, go to the [Results] tab

 

 

 and click [Show Numerical Summary Table].

 

 

 

The vectors of the electric field are shown below.

 

The electric field is generated between two plates.

 

The gradation contour of the electric potential on the XZ cross section is shown below.

 

You can visually grasp the distributed electric potential in the space around the electrodes.