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Resistance in 2D and 3D model
 
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radoslaw.jez
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Joined: 10 Nov 2008
Posts: 12
Location: Silesian University of Technology, Gliwice, Poland

PostPosted: Mon May 18, 2009 7:54 am  Reply with quote

I would like to ask about difference in results of 2D and 3D simulation. I have simulated massive Cu conductor in two cases 2D and 3D (all dimesions are the same, element types are correspondingly 2D - PLANE53, 3D - SOLID97, DC simulation without Fe-materials, conductor supplied by external circuit CIRCU124).

In the case of 2D simulation results of resistance is the same as the value calculated from equation (R=rho*lenght/(cross_section)). But in the case of 3D model the value of resistance is lower and is equal about 70% of resistance calculated in 2D model. This phenomenon occurs in different geometrices of massive conductor. (All parameters and dimensions are directly the same in both (2D and 3D) models).

Where can be a problem with proper result of 3D model?

Thank you very much for any answer or suggestion

Best regards

Radoslaw Jez
Silesian University of Technology
Gliwice, Poland
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mike.yaksh
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Joined: 05 Feb 2009
Posts: 291

PostPosted: Mon May 18, 2009 9:09 am  Reply with quote

Hi Radoslaw

Is this static or a harmonic at some frequency? How does the current
distribution over the cross section between the 2D and the 3D compare
between the two models? What are the peak values of both? I am
assuming this is a planar model for the 53's (keyopt(3)=0), correct. I
am assuming the powers (POWERH) are also off by the same 30% factor,
correct? What were the element options for each model?

Mike Yaksh
NAC International
Norcross GA

-----Original Message---- radoslaw.jez [--email address suppressed--]
I would like to ask about difference in results of 2D and 3D simulation.
I have simulated massive Cu conductor in two cases 2D and 3D (all
dimesions are the same, element types are correspondingly 2D - PLANE53,
3D - SOLID97, DC simulation without Fe-materials, conductor supplied by
external circuit CIRCU124).

In the case of 2D simulation results of resistance is the same as the
value calculated from equation (R=rho*lenght/(cross_section)). But in
the case of 3D model the value of resistance is lower and is equal about
70% of resistance calculated in 2D model. This phenomenon occurs in
different geometrices of massive conductor. (All parameters and
dimensions are directly the same in both (2D and 3D) models).

Where can be a problem with proper result of 3D model?

Post generated using Mail2Forum (http://www.mail2forum.com)
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radoslaw.jez
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Joined: 10 Nov 2008
Posts: 12
Location: Silesian University of Technology, Gliwice, Poland

PostPosted: Mon May 18, 2009 9:35 am  Reply with quote

Hi Mike

This is static analysis DC . In both cases (2D and 3D) current value is I=1A (current source). Next, the voltage along the conductor is read and the resistance is calculated. In 2D case: ET,1,53, !air area; ET,2,53,4 !conductor area, in 3D case: ET,1,97, !air volu; ET,2,97,4 !conductor volu.

In 3D case the voltage along the conductor is smaller. This fact gives also smaller value of resistance, power losses, maximal magnetic field distribution.

The shape and dimensions of mesh are identity in case 2D (triangle) and 3D (tetrahedral).

Radoslaw Jez
Silesian University of Technology
Gliwice, Poland
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mike.yaksh
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Joined: 05 Feb 2009
Posts: 291

PostPosted: Mon May 18, 2009 1:29 pm  Reply with quote

Hi Radoslaw

If this is a static analysis, you are basically solving a electrical
conduction problem, only. The magnetic field does not contribute to any
redistribution of the current due to an eddy current effect.

I tried a simple 97 with massive option, and ran into a similar problem.
I will look at some more. The 69 works well and gives good numbers
which would be the same as the 97 in static problem with the massive
conductor.

Mike Yaksh
NAC International
Norcross GA

-----Original Message---- radoslaw.jez [--email address suppressed--]

This is static analysis DC . In both cases (2D and 3D) current value is
I=1A (current source). Next, the voltage along the conductor is read and
the resistance is calculated. In 2D case: ET,1,53, !air area;
ET,2,53,4 !conductor area, in 3D case: ET,1,97, !air volu; ET,2,97,4
!conductor volu.

In 3D case the voltage along the conductor is smaller. This fact gives
also smaller value of resistance, power losses, maximal magnetic field
distribution.

The shape and dimensions of mesh are identity in case 2D (triangle) and
3D (tetrahedral).

Post generated using Mail2Forum (http://www.mail2forum.com)
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