[Getdp] [GetDP] Calculation of an Integral quantity
Olivier Castany
castany at quatramaran.ens.fr
Tue Apr 24 14:48:59 CEST 2007
Hello,
I would like to compute a magnetic field in two ways :
- by FEM Galerkin
- by integration (Biot and Savart law)
I am trying these calculations on a simple geometry (a troidal coil) and
want to compare the results (hoping they will be the same).
I can solve the Galerkin equations with a vector potential formulation
(gauged by a spanning tree) and the result is perfect. However I have
problems with GetDP's integral quantities...
The .geo and .pro files are attached and here are my questions :
-----------
On the gmsh mailing list Christophe Geuzaine wrote (Sun, Apr 22, 2007) :
> In an "Integral" quantity the coordinates of the "source" integration
> point are denoted by XS[], YS[] and ZS[]. X[], Y[] and Z[] will give you
> the coordinates of the "observation" point.
OK, I managed to do something with $XS (I thought the source point
would be implicitly taken, but this is not the case), but :
GetDP : Error ('torus.pro' line 130): Unknown Function: XS
are you really sure you have implemented XS[] ? or how can it be used ?
(I have seen no example of $XS or XS[] on the web, the wiki or the GetDP
mailing list)
-----------
There are several results which are weird or simply wrong :
- as a test, I tried to calculate \int_{Coil} J_s : the result should be
\vec 0 but something very different and weird is obtained (see a2.pos)
(I think this point should really be clarified, because if it doesn't
work, there is few chance that the rest will)
- the direction of B2Z is reversed (although I think I carefully checked
the signs of GradLaplace and the cross products)
- B2Z should be equal to B1
- does the integral quantity result depend on the FunctionSpace basis
type used (BF_Edge or BF_Facet) ? it seems it does not.
-----------
It would be quite encouraging if someone could tell the correction which
would make the file torus.pro work properly.
Have a nice day,
O.C.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: torus.tgz
Type: application/x-gtar
Size: 68069 bytes
Desc: not available
URL: <http://www.geuz.org/pipermail/getdp/attachments/20070424/00cd7b7d/attachment.tgz>