[Getdp] Possible Bug: 2*pi missing when integrating over Volumes in Axisymmetrical Models

Ruth V. Sabariego r.sabariego at ulg.ac.be
Sun Mar 8 09:05:51 CET 2009


Hi Malte,
There is no error in the formulation. The factor 2*Pi should be included 
manually when integrating or using global quantities in the formulation. 
For the local quantities, it is properly accounted for within the Jacobian.
We usually define a 'CoefGeo=2*Pi ;' in the axisymmetric problems.
Your result is thus correct.

Regards,
Ruth



Dr.-Ing. Malte Hinrichs wrote:
> Hello!
>
> First of all, I want to thank your for your great dedication to the 
> development of a powerful OS-FEM-Suite!
>
> When evaluation the total field-energy in an axi-symmetrical model  I 
> stumbled across the phenomenon that the result is too low by the 2*pi. 
> I verified this behaviour by integrating the constant 1 over a 
> cylindrical Volume with the dimensions D=10 mm and L=10 mm.
> The result yields 0.5e-7 (= Rm * D * L, Rm=D/2), while it should be 
> 2*pi*Rm*D*L=pi*1.e-7.
>
> I included an example project, which is mainly an adaptation of your 
> magnetostatic example files.
> Name of cylindrical Volume: Arm - Armature
> Relevent lines:
> debug.geo: 5-9, 31-42
> debug.pro: 23, 116
> Mag-2D-AZ-Debug.pro: 174
>
> Please let me know, if this is not a Bug, but an error on my side!
>
> Sincerely,
>
> Malte Hinrichs
>
>
> "getdp --version"
> 1.2.1
>
> "getdp debug -pre MagSta_a   -cal -pos a" :
> ...
> P o s t - P r o c e s s i n g . . .
> Info      : Selected PostProcessing 'MagSta_a'
> Info      : Selected Mesh 'debug.msh'
> Operation : PostOperation 1/5
>          > 'a.pos'
> Operation : PostOperation 2/5
>          > 'b_a.pos'
> Operation : PostOperation 3/5
>          > 'Wint.pos'
> Operation : PostOperation 4/5
>          > 'w.pos'
> Operation : PostOperation 5/5
> 0  4.999999999979999e-07                             <--- This is it
> Resources : cpu 0.576036 s
> E n d   P o s t - P r o c e s s i n g
> E n d
>
>
>
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>   


-- 
Dr. Ir. Ruth V. Sabariego
University of Liege, Institut Montefiore,
Dept. of Electrical Engineering & Computer Science, 
Applied & Computational Electromagnetics (ACE),
Sart Tilman Campus, Grande Traverse, 10 (B28), B-4000 LIEGE, Belgium
phone: +32-4-3663737 -- fax: +32-4-3662910 -- http://elap.montefiore.ulg.ac.be/




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