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coupling Electric Currents and Magnetic Fields

Posted Jul 25, 2012, 6:16 a.m. EDT Low-Frequency Electromagnetics, Modeling Tools & Definitions 4 Replies

Ceren B
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Hi everyone!

If a model consists of both electric currents (or electrostatics) and magnetic fields separately (not using MEF), how do you couple them to make possible the magnetic fields can be produced due to the existence of electric currents?

It is not enough to create both interfaces and leave like that, right? I tried it, observed it didn't work.
I also tried a way to couple but I'm not sure of my method. Is it safe to define external current density in magnetic fields and type the ec.Jx, ec.Jy and ec.Jz in the vector components to make it?


thank you
4 Replies Last Post Aug 6, 2014, 4:20 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 25, 2012, 4:31 p.m. EDT
Hi

check your dependent variables, ES and EC solves for V, MF for A (vector), and MEF for A and V.
Therefore normally with MEF you include ES or EC in addition to MF.

The main difference between ES and EC is that ES is static (no current flow) while EC you have charge displacements i.e. currents flowing

If you add ES and MEF you are solving twice for V (V & V2), that is tricky as you need to manually couple both to respect continuity

--
Good luck
Ivar
Hi check your dependent variables, ES and EC solves for V, MF for A (vector), and MEF for A and V. Therefore normally with MEF you include ES or EC in addition to MF. The main difference between ES and EC is that ES is static (no current flow) while EC you have charge displacements i.e. currents flowing If you add ES and MEF you are solving twice for V (V & V2), that is tricky as you need to manually couple both to respect continuity -- Good luck Ivar
Jumril Yunas
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Posted: 1 decade ago Apr 4, 2013, 11:19 a.m. EDT
last time I used separate module to see the membrane bending due to the magnetic force . first I used AC/DC module to analyze the magnetic field induced by current carrying coil. then calculate the Fz. next I used Fz to create Pressure on membrane. The value is then used to analyze the membrane deflection using MEMS module.
do I have the right method ?
last time I used separate module to see the membrane bending due to the magnetic force . first I used AC/DC module to analyze the magnetic field induced by current carrying coil. then calculate the Fz. next I used Fz to create Pressure on membrane. The value is then used to analyze the membrane deflection using MEMS module. do I have the right method ?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 4, 2013, 2:49 p.m. EDT
Hi

this is the decoupled method, assuming that the displacement of the SOLID is small and will not change the magnetic force evaluation (or for other cases the electrostatic force, if this applies). This approach is the cassical one, one pyhsics at the time and used by older traditional FEM programmes.
But with COMSOL it's rather easy to couple fully both physics, then you are sure that any changes in the solid deformation is observed by the ACDC physics and taken correctly into account (true coupled multi-physics ;)

To get the solid deformation to change the ACDC physics, you need mostly to use the ALE physics to adjsut the "air shape" (just ensure you put the ALE node BEFORE = ABOVE the SOLID physics node in your node tree list, use the up/down commands).

There are a few examples in the model library I kind to remember ;)
--
Good luck
Ivar
Hi this is the decoupled method, assuming that the displacement of the SOLID is small and will not change the magnetic force evaluation (or for other cases the electrostatic force, if this applies). This approach is the cassical one, one pyhsics at the time and used by older traditional FEM programmes. But with COMSOL it's rather easy to couple fully both physics, then you are sure that any changes in the solid deformation is observed by the ACDC physics and taken correctly into account (true coupled multi-physics ;) To get the solid deformation to change the ACDC physics, you need mostly to use the ALE physics to adjsut the "air shape" (just ensure you put the ALE node BEFORE = ABOVE the SOLID physics node in your node tree list, use the up/down commands). There are a few examples in the model library I kind to remember ;) -- Good luck Ivar
gsairus
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Posted: 1 decade ago Aug 6, 2014, 4:20 p.m. EDT
Hello Ivar,
could you possibly tell how it could be done with "manually couple" for V&V2? I have got my solution in ec/frequency domain and now I really wonder if I can use obtained current density for second physic - mf (somehow through Je?) to get a magnetic field pattern?
Thank you very much for the replay!
Hello Ivar, could you possibly tell how it could be done with "manually couple" for V&V2? I have got my solution in ec/frequency domain and now I really wonder if I can use obtained current density for second physic - mf (somehow through Je?) to get a magnetic field pattern? Thank you very much for the replay!

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