Current Solver Test

Elmer cases by the users for the users
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Joined: 07 Apr 2010, 09:56

Current Solver Test

Post by madstamm » 10 Jan 2012, 15:28

Hi All,

This is a complete file package with which you can test the CurrentSolve solver.
Current through a AWG20 wire is solved for, when applying 0.1V. The Whitney EM solver is also used to calc the resulting magnetic field.

To make sure my models were being correctly calculated, I modelled the following:
- 5cm AWG20 copper wire with expected resistance of 1.72mOhm
- 0.1V across the wire, should result in 5.8W power loss
- Aircube with 10cm sides at zero potential
- the two objects are meshed in conformal fashion using salome, allowing correct electromagnetic modeling. Note that this is key to making this work.

Result: It works nicely! Part of the solver log:
StatCurrentSolve: Total Heating Power : 5.8175872743848025
StatCurrentSolve: Effective Resistance : 1.71892565222538573E-003

The Salome python script that generates the model and mesh can be found here:
(1.21 KiB) Downloaded 451 times
The sif file is here:
(1.25 KiB) Downloaded 492 times
And finally, the project folder is below. You can extract the folder and open it as a project in elmer - but note that you have to generate the sif file, then edit it, load case2.sif, save it as case.sif and only then start the solver. I dont have the project set up for ElmerGUI, and the GUI overwrites the case by default.
(1.58 MiB) Downloaded 516 times
VTK showing the electrical potential on the wire

VTK showing the potential and the magnetic flux

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Re: Current Solver Test

Post by orcaja » 25 Jun 2012, 19:12

Thank you for sharing, I have a question about this case. In the .sif file there are two lines in the boundary conditions, they are:

P {e}= real 0
P = Real 0

and I'm tryin to understand what they mean, I also saw in the solve log, the following:

Model Input: Unlisted keyword: [p {e}] in section: [boundary condition 1]
Model Input: Unlisted keyword: [p] in section: [boundary condition 1]

can anyone explaint to me what do they mean?
thank you in advance.

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Re: Current Solver Test

Post by raback » 25 Jun 2012, 19:48


This is a special solver which includes nodal degrees of freedom used for the scalar potential and edge degrees of freedom used for the vector potential. The latter choice ensures that the vector potential by construction is divergence free i.e. satiesfies the Coulomb gauge.

In Elmer the Dirichlet conditions are high-level matrix operations. If the variable name is "varname" then the normal way to set Dirchlet conditions would be "varname = 0". Now this only sets the nodal dofs. In this case we also want to set the edge dofs and for the reason a convention "varname {e} = 0" was introduced.

So in this particular case "p=0" set the scalar potential to zero, and "p {e}=0" sets the normal component of the vector potential to zero.


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