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Unknown variables ec.Jx, ec.Jy and ec.Jz?

Posted Oct 5, 2011, 2:02 p.m. EDT 0 Replies

W. Wong
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I am using COMSOL V4.1 and I am trying to model the deformation of a metal sheet under the influence of magnetic forces, caused by a time-dependent current on a (3D) coil. Using only Electric Currents (ec) and Magnetic Fields (mf), there does not seem to be any issue. One end of the coil is assigned Ground and the other end a time-dependent potential. I linked this current to Magnetic Fields by setting ec.Jx, ec.Jy and ec.Jz as external current density. With this, I get Arrow Volumes and Surfaces of the electric current and magnetic flux that seem reasonable.

However, I ultimately need the deformation of the metal sheet, for which I need Solid Mechanics. For some reason, after adding this, the ec.Jx, ec.Jy and ec.Jz in the external current density immediately become orange, with COMSOL claiming those variables are unknown. I tried this with several other "random" Physics such as a few from Acoustics and Fluid Flow, but none of these cause those variables to turn orange.

Can anyone explain to me why Solid Mechanics turns the components of the external current density in Magnetic Fields to unknown? Merely its existence alone has this effect, even when disabled.
0 Replies Last Post Oct 5, 2011, 2:02 p.m. EDT
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Hello W. Wong

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