[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

Innovative Systemlösungen der Energie- und Elektrotechnik
www.enertex.de           

Erlachstraße 13                 91301 Forchheim
St.-Nr. 9216/125/50473      UST-ID DE 216 837 306
Registergericht Bamberg   HRB 4569
Volksbank Forchheim eG, BLZ 763 910 00, Kto.-Nr. 7200480       
Tel: ++49-9191-975217 Fax: ++49-9191-974 687

 CAUTION: 
 This message may contain privileged and confidential information intended
 only for the use of the address named above. 
 If you are not the intended recipient of this message you are hereby notified
 that any use, distribution or reproduction of this message is prohibited.

 If you have received this message in error please notify the sender of this
 message immediately.