Home / Examples / Electric Analysis [Coulomb] / Example 5: Electric Field Created by Point Charge

Example 5: Electric Field Created by Point Charge

General

• In this example, a point charge is placed in the air.
   

• The electric field created by it is solved and the equipotential map is acquired.
   

• 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

 

As air domain cannot be created automatically for this model, automatic creation is deselected.

(There are vertex bodies only. Air domain size is not fixed automatically.)

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

Model

A solid body represents the air. A vertex body placed in the center of the air represents the point charge.

Body Attributes and Materials

The vertex body is used to set the point charge in the body attribute.

Assign a material to it even though the material property does not affect the simulation.

Body Number/Type	Body Attribute Name	Material Name
0/Solid	Air	000_Air(*)
1/Vertex	Dot	000_Air(*)

* Available from the material DB

 

Point charge is set in the body attribute.

Body Attribute Name	Charge
Dot	Electric Charge: Electric Charge 1x10-12 [C]

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Outer Boundary Condition *	Electric	Open Boundary

 

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

 

and click [Outer Boundary Condition] .

 

Results

The isosurface contour of the electric potential is shown below.

At Minimum/Maximum Values on the Contour tab of [Graphics Setup], deselect [Automatic] and set 0.5 => 5.0.

 

The figure shows the equipotential map.