[Getdp] Magnetic Force 3

[Kubicek Bernhard]

I calculate a Lorentz Force density in the Postprocessing by the following expression (having a temperature-field-dependent conductivity):

f=jxB=-conducivity(T(x))*grad(V)xCurl(A)=conductivity*Curl(A)xgrad(V)

{ Name f ; Value { Term { [ con[{T}]*({Curl a} /\{d v1})] ; In Vol ; Jacobian Vol; } } }

This works in my case. 

Maybe this helps you, 
nice greetings from rainy Vienna,
Bernhard Kubicek


-----Ursprüngliche Nachricht-----
Von: getdp-bounces at geuz.org [mailto:getdp-bounces at geuz.org] Im Auftrag von Jasper
Gesendet: Donnerstag, 3. August 2006 23:01
An: getdp at geuz.org
Betreff: [Getdp] Magnetic Force 3


Hi,

I've used a scalar potential to calculate the field in a 3D magnetostatics problem. Looking at the fields the results look correct. Now I would like to calculate the force on a object due to this magnetic field.
>From what I can gather from the mailing list several people have
already done this before, but I have yet to find any examples. It appears the force can be calculated in three different ways:

- Take the B-field, and compute 1/mu0 * B x ( Curl B ) over the volume. This is probably easiest achieved in PostProcessing or Gmsh, but somehow the Curl B of my field in Gmsh returns zero...
- Compute the Maxwell Stress Tensor using the B-field, and integrate it over the surface of the object. This is probably best performed in PostProcessing, but I'm at loss on how to go from the B-field in the element volumes to the field at the surface of the object.
- Using Virtual Works. No idea how to do that, but it probably involves small displacements :-)

If anybody can show me some examples of computing these quantities it would be very much appreciated. Thanks in advance for your help. Best regards,

Jasper
_______________________________________________
getdp mailing list
getdp at geuz.org
http://www.geuz.org/mailman/listinfo/getdp