Elmer Discussion Forum

Dear all,

I started to work with elmer recently and I wanted to do some tutorials. The first tutorial Heat equation – Temperature field of a
solid object worked well, but the harmonic current in a wire shows strange output values. While the field looks the same, the scaling is off.
I attached my .sif and a picture of the output of the real part of the magnetic flux density.

Cheers,
Tobi

You are plotting magnetic field strength not magnetic flux density. The tutorial does the latter.

Hi Kevin,

thanks a lot for your fast reply and sorry that I have attached the wrong image. The manual states a flux density of 0.524 T and 0.107 T (im and re) . In the picture I only get a peak density of 5.2e-3T and 1.1e-3T (im and re) so I am 2 magnitudes wrong. Do I converte the unit wrong, I thought it is in T.

Cheers,
Tobi

There is an inconsistency in the tutorial, the calculations and results are for a wire 0.01 M radius. However the wire.grd file provided has a radius of 1.0 and with the coordinate scaling in the sif file 0.001 the radius being used in the solver is 0.001 M.

You may want to review this topic
viewtopic.php?f=7&t=7021&p=22382&hilit=wire.grd#p22382

Hi Kevin,

thanks a lot for your answer. I read throught the forum post you have linked, but as far as I have understood it, Ilja used 0.01m as radius while the radius used in the simulation is 0.001m for calculating the analytical solturion. If he had put in 0.001m it would have been the stated 0.037T. I only solved the harmonic case before, I set the frequncy to 100Hz and solved the static case too. The thing is now I get the 0.037T for my flux density for the same scaling and wire.grd, so here I get what is stated in the manual (I attached the result of the flux density and my casae.sif). Only the harmonic case output shows a difference of 2 magnitudes.

i am sorry for my confusion.

Cheers,
Tobi

Because of the radius inconstancy and scaling, even 100 Hz is too high. Use 1 HZ and you will get the same answer as steady state.