[Getdp] High error by calculating the time derivative in postprocessing
Jürgen Schuhmann
schuhmann at enertex.de
Thu Oct 4 19:36:13 CEST 2007
Dear Christophe,
first i want thank you for developing such a mighty tool like getdp.
I am calculating the current distribution in busbars for currents up to 5kHz
with getdp.
In case of higher frequencies the skin and proximity strongly inluences the
current distribution. This leads to very low currents in the interior of the
busbars.
By posprocessing the current-distribution a high error occurs at the
locations, where the vector-potential a is very low. I think this results
from the time derivative of the vector potential in the formula:
jz=sigma[]*CompZ[(Dt[{a}]+{ur}).
Of course, the error vanishs by decreasing the time step. But i have to set
2000 timesteps per period to get an useful result.
If i calculate the same problem in frequency domain, then the resulting
current distribution is very accurate.
So my Question:
Is there any way to increase the accuracy of the time derivative used in the
postprocessing?
By the way is there a way to calculate the time derivative of a an integral,
i.e.
Dt {Integral { [ - sigma[]*CompZ[({a} ] ] ; In DomainC_Mag ;Jacobian Vol ;
Integration CurlCurl ; } }}
This would be useful because the time charakteristic of the integrated field
is much smoother than the local field.
Thank you for your help.
J. Schuhmann
--
___________________________________________________
Dipl.-Ing. Jürgen Schuhmann
Simulation u. Hardware-Entwicklung
Enertex Bayern GmbH
Geschäftsführer: Dr.-Ing. Michael Schuster
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