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HELP WITH AC/DC MODELING

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Hi, I would like to model the Voltage induced in a coil, between its ends, by moving a permanent magnet back and forth inside the coil.

The User's Guide suggest to solve, when possible, the problem in 2D, but for a spiral coil I think there is no symmetry for the coil (since if I rotate the circles which represent the circular cross-sections of the wire they are going to form straight loops and in the spiral coil the loops are not straight), so maybe I should work in 3D.

Anyway,

1. Which application in ACDC module is more suitable for this model: STATICS MAGNETIC OR QUASI-STATICS MAGNETIC?

2. Can somebody give me advice on how to represent in COMSOL the motion back and forth of the magnet?

Please see the attached file.

Thank you for your help.




1 Reply Last Post 22 nov. 2010, 15:35 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 22 nov. 2010, 15:35 UTC−5
Hi

firsst of all to make it simple use 2D, it's so much faster to solve, then check in 3D to be sure you have not forgotten any 3D coupling effects, or border effects.

Then conceptually what is different from N turns of a coil and 1 turn ? N being fixed you can put it anywhere in the equations, including extracting it fully from your problem, at least to begin with.

Now static field is "not moving", by definition, you should rather check the BC's availble in the two cases to see which one seems the best (and read carefully the doc about the limitations of each physics / application mode)

for moving objects you have either specific BC's, or you define a moving Br or M of the magnet. Anyhow, should you use transient of a harmonic devvelopment of the type frequency sweep ?

--
Good luck
Ivar
Hi firsst of all to make it simple use 2D, it's so much faster to solve, then check in 3D to be sure you have not forgotten any 3D coupling effects, or border effects. Then conceptually what is different from N turns of a coil and 1 turn ? N being fixed you can put it anywhere in the equations, including extracting it fully from your problem, at least to begin with. Now static field is "not moving", by definition, you should rather check the BC's availble in the two cases to see which one seems the best (and read carefully the doc about the limitations of each physics / application mode) for moving objects you have either specific BC's, or you define a moving Br or M of the magnet. Anyhow, should you use transient of a harmonic devvelopment of the type frequency sweep ? -- Good luck Ivar

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