Home / Examples / Electric Analysis [Coulomb] / Example 4: Floating Electrode's Potential

Example 4: Floating Electrode's Electric Potential

General

• The model consists of four plate electrodes arranged in parallel. Electric potential is applied
  between the top and bottom electrodes. Intermediate electrodes are floating.
   

• The capacitances across the electrodes, 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

 

The electric field exists outside the analysis region. 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 4 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.

The other two are used to imprint the floating electrode 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
3/Sheet	Imprinting body
4/Sheet	Imprinting body

* Available from the material DB

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Specifications
Electrode1/Face	Electric	Electric Wall	Electric Potential Specified -1 [V]
Electrode2/Face	Electric	Electric Wall	Electric Potential Specified +1 [V]
Floating1/Face	Electric	Electric Wall	Floating Electrode
Floating2/Face	Electric	Electric Wall	Floating Electrode
Outer Boundary Condition *	Electric	Open Boundary

 

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

 

and click [Outer Boundary Condition] .

 

Results

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

 

 

 and click [Show Numerical Summary Table] .

 

The capacitances of floating electrodes are as follows.

 

 

The capacitances of fixed electrodes are as follows.

 

 

The vectors of the electric field are shown below.

 

 

 

The gradation contour of the voltage on the XZ section is shown below.

 

 

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