Directory:
    ${PENCIL_HOME}/samples/1d-tests/telegraph_eqn_alpha2
SVN Id:
    $Id$
Maintainer:
    Axel Brandenburg <brandenb/nordita[dot]org>
Added:
     7-Jan-2011
Status:
    succeeds # One of [succeeds|failing since <date>|obsolete| ...]
Recommended resolution:
    32x1x1 for eta=0 is fine.
References:
    The formalism is close to that used in:
    Brandenburg, A., Käpylä, P., & Mohammed, A.: 2004, ``Non-Fickian
    diffusion and tau-approximation from numerical turbulence,''
    Phys. Fluids 16, 1020-1027, astro-ph/0306521

Comments:
The equations solved are dA/dt=EMF, and dEMF/dt = (alpha*B-etat*J-EMF)/tau.
The dispersion relation is (lam+eta*k2)*(1+lam*tau)=+/-alp*k-etat*k^2.
Solutions for alp=1.2, etat=1, in a domain of length 2pi are:

  1/tau   lam
   1.0   0.171
   0.5   0.153
   0.2   0.124
   0.1   0.100