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How to model magnet falling inside copper tube in 3d?
Posted 5 gen 2016, 01:54 GMT-5 Low-Frequency Electromagnetics Version 5.0 0 Replies
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I have done all the geometries and physics, replicating the 2d axisymmetric version of the falling_magnet.mph in 3d but I do not have a velocity, lorentz term that I can use for my copper tube domain.
I read Ivar's answer in this thread www.comsol.co.in/community/forums/general/thread/14891/
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If we consider the magnetic field you can solve it in stationary mode, extract the Eddy current forces related to a velocity displacement (note: in v4.1 the Lorentz velocity term is not yet set up in 2D, you must complete the BC with the equations, good exercise to write out the curl ;) and then add a global equation GE solving the velocity of the falling magnet expressed as derived from canceling out / minimising gravity forces with the magnetic Eddy current forces. Then you solve this independent ODE in the time domain and at each step you run a stationary for the MEF. You have hence a coupled problem and you solve it in the time domain, with MF/MEF
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But I do not know how to "complete the BC with the equations" .I know that the equation I have to add is : Ji=sigma*E + sigma*v x B where Ji is the induced current density.
How does one give such an equation and where? How are the vectors "v" and "B" defined? I have defined sigma as a parameter and hence, I have no problem with it.
Please tell me as to how I have to proceed, in a detailed manner.
Hello Sidarth S
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