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Reduced potential not working in transient mode (cannot find initial values)

Posted Aug 11, 2010, 1:15 p.m. EDT 0 Replies

Nicholas Eidietis
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I am trying build a model with a strong background toroidal magnetic field. As a simple test case, I am using the AC/DC module "Meriodonal Induction Currents, Vector Potential" application mode (axisymmetric) and defining a single domain, which is a square with the left edge at R=0.

I use the "reduced potential" mode to specify the background magnetic vector potential of a long straight wire at R=0:
Az = u0*I/(2*pi)*log(r).

Boundary conditions: Left: axisymmetry, Other boundaries: Az = -mu0_emqap*1e6[A]/(4*pi)*log(r)


Run in static mode, I get the correct answer (Bphi scaling with 1/r). However, if I switch to transient mode (still with constant vector potential), the results are dependent upon the conductivity of my subdomain. If I set the domain to high conductivity (copper), the transient solution is fine, simply repeating the static solution. However, if I make the domain conductivity very low or 0 (air), the solver fails with the error "Failed to find consistent initial values.".

Is it possible to specify a strong background field in low conductivity domains? I need to model my processes in air with a strong background field, so I am really stuck on what I thought would be a trivial part of my model.
0 Replies Last Post Aug 11, 2010, 1:15 p.m. EDT
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Hello Nicholas Eidietis

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