I created a model for a coil located over a conductor, coil is a multiturn coil with driving current of 1 amper. I modeled the half of geometry and the quarter of geometry. By decreasing the geometry from half to quarter the coil inductance value is getting half but this does not happen for the coil resistance. In fact I get a wrong value for the resistance of the coil. Could anybody take a look at these models and help me to find the mistake?
Are you doubling the flux to allow for looking only at a quarter? This is in your calculation of L. S.R.H. Hoole
Hello Mr.Hoole
In fact I am trying to reduce the geometry and subsequently mesh elements to get faster runs.
when I divide the complete model to half (considering that I keep the drive current and number of turns same), the inductance(L) decreases to half but this is not the same for the coil resistance. That is why I think there should be a problem in my model. Hope I could use any of your kind advises.
Regards,
Hi Ehsan,
When you cut the geometry in half (or into a quarter) in order to reduce the number of mesh elements, it's important that this symmetry operation maintains the true geometry of the original object, and that the appropriate boundary condition is enforced at the plane of symmetry. If you have a multi-turn coil, I'm not sure that you can invoke symmetry at all, so I think you might not be able to utilise a half or quarter model to represent the original coil. This might explain your results.
Regards,
Ray Simpkin
Hi, change the conductivity of wire or change the diameter of wire in the coil, it may work, good luck.
Hi Dear Ray,
For nearly two months I have been trying to run my simulations with whole model geometry. In fact, I am not able to use a complete geometry anymore due to the complexity of the coil I am working on. I read a comsol blog and subsequently decided to reduce the geometry, You could find it at:
http://www.comsol.com/blogs/exploiting-symmetry-simplify-magnetic-field-modeling
This writer started with a simple numerical multi-turn coil, however I think this could be applicable for a coil over a conductor since the same boundary conditions can be used for symmetry planes of conductor. From the other hand, the results of L seems to be promising for half and quarter model, the problem insists on the R part.
Regards,
Ehsan
Hi Mr. Shahram,
Those values inserted in simulation are mostly taken from a experimental reference work which is done by SK Burk. The title of his works is:
"A benchmark problem for computation of ΔZ in eddy-current nondestructive evaluation (NDE)"
And being honest, I don't know how changing the coil turns or conductivity could help on matching the results, I really appreciate it if you could help me on this issue by providing a more detailed explanation. Thanks in advance.
Regards,
Ehsan
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