[Getdp] basic permant magnet question - please help

[Pei-Ying Hsieh]

Dear GetDP users:

I just started learning about magnetism.  I have a couple of basic 
questions that I am not able to figure out.  It will be appreciated if 
someone here can shed some light on this.

I have a permanent magnet - no electric current in the domain.  I would 
like to calculate the magnetic flux density.

I have found a 3D code posted by Jasper in 2006.  The questions are:

1. The governing equation for magnetostatics filed is:
    Curl ( nu * Curl A) = J, where A is vector potential and J is electric 
current density.
    Now, since there is no current, I will think that J is zero.
2. In the Formulation of getdp code (2D Magnetostatics example on getdp 
wiki),
    it showed:
       Equation {
                    Galerkin { [nu[] * Dof{ Curl a}, {Curl a}]; In Domain; 
Jacobian JVol; Integration I1; }
                    Galerkin { [hc[], {Curl a}; In Domain_M; Jacobian 
JVol; Integration I1;}
        }

How does {hc[], {Curl a}} come into the equation? I believe that hc is 
Coercitivity of the magnet?

Thanks in advance for your reply!

Best Regards,

Pei
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