help with GetDP needed
Christophe Geuzaine
Christophe.Geuzaine at ulg.ac.be
Wed Dec 1 14:56:40 CET 1999
Samuel Kvasnica wrote:
>
> > Your mistake was that you associated the HBF basis functions to the
> > nodes, not to the edges...
>
> Well, I'm really blind, I checked everything twice and didn't notice that. Now it works
> perfectly, very smooth results. Thanks a lot. Is there some reasonable short .pdf or .ps
> document
> covering overview of FEM and explanations of basis functions, integration methods etc. ?
Hmm, I dont't have something in mind right now, but we were thinking
about adding some more 'technical' comments to the user's guide, just to
explain a bit more the fundamentals. Otherwise, I could recommend you a
very good book, by Alain Bossavit :
@book{mixt:bossavit:98,
author = "A. Bossavit",
title = "Computational Electromagnetism, Variational Formulations,
Edge
Elements, Complementarity",
publisher = "Academic Press",
year = 1998}
>
> > PS : is your problem truly 2D? Or is it axisymmetric? In the latter,
> > your jacobian methods are not correct...
>
> Yes, it's truly _axissymetric_. Seems like I forgot to replace Vol and VolSphShell by
> VolAxi and VolAxiSphShell in jacobian. So it seems like I was computing field of
> 6 infinite inducotors with infinite core. Now I replaced it. There's almost no difference
> in
> the form of the field but the results don't quantitatively correspond to my measurements !
> The Br component should be 0.07T 17mm from axis at pole position (with 150 windings of
> inductor with
> 7A current at each segment), which was in a strange way
> true for Vol and VolSphShell. Now it is ~50 times less. Well, actually a factor of 16*pi.
> It there something else to be changed except jacobian ?
Oups, yes, there is an another small error in the PostProcessing field:
you should give each postprocessing quantity the type of jacobian to use
in the interpolation.
Before:
PostProcessing {
{ Name MagSta_a_2D ; NameOfFormulation Magnetostatics_a_2D ;
PostQuantity {
{ Name a ; Value { Term { [ {a} ] ; In Domain_Mag ; } }
}
{ Name az ; Value { Term { [ CompZ[{a}] ] ; In Domain_Mag ; } }
}
{ Name b ; Value { Term { [ {d a} ] ; In Domain_Mag ; } }
}
{ Name h ; Value { Term { [ nu[] * {d a} ] ; In Domain_Mag ; } }
}
}
}
}
After:
PostProcessing {
{ Name MagSta_a_2D ; NameOfFormulation Magnetostatics_a_2D ;
PostQuantity {
{ Name a ; Value { Term { [ {a} ] ; In Domain_Mag ;
Jacobian Vol ; } } }
{ Name az ; Value { Term { [ CompZ[{a}] ] ; In Domain_Mag ;
Jacobian Vol ; } } }
{ Name b ; Value { Term { [ {d a} ] ; In Domain_Mag ;
Jacobian Vol ; } } }
{ Name h ; Value { Term { [ nu[] * {d a} ] ; In Domain_Mag ;
Jacobian Vol ; } } }
}
}
}
It's a 'bug' in this version of the code: if no jacobian is given, getdp
assumes that the classical placement has to be applied (-> without the
axysymetric transformation...)
--
Christophe Geuzaine
Tel: +32-(0)4-366.37.10 mailto:Christophe.Geuzaine at ulg.ac.be
Fax: +32-(0)4-366.29.10 http://www.montefiore.ulg.ac.be/~geuzaine/