# Electrostatic simulation- getting a field value

Dear FF users and developers,

I have a general question regarding Free FEM software. To be clear, I have no experience with Free FEM. I’ve read FF user manual and a few tutrorials, but I did not manage to find the answers to my questions.

What I need to do create and solve 2D model representig the geometry around transformer windings (combination of bare/ paper insulated electrodes, insulating elements and transformer oil as liquid dielectric). For the purpose of post-processing I need to calculate („draw“) electric field streamlines in oil (between insulating elements). To do so, I need to get a field value (Ex, Ey) as well as dielectric constant (relative permittivity) at a certain point (x,y).

1. Can Free FEM do that- extract el. field values (Ex, Ey) and relative permittivity at predefined points?

2. Will domain with several regions (10-20) of different permittivty (dielectric constant) be a problem for Free Fem? Will it be complicated to write a function for permittivity?

The questions may be stupid, but answering them would save me a lot of time😊

Thanks in advance.

It is not so difficult to choose or change the numbering of the region in FreeFEM with the
“change” function.

After it is write simple so cha7nge value for a region number;

real [int] Perm=[1,2,3,4,5,6,7,8]; // 8 go region form 0 to 7.
and in formulation use
perm[region] ( this is equal (region+1) ) the the formulation.