[CIG-MC] Internal heating with CitcomS

[Bradford Foley]

I'm using CitcomS-2.2.2 and am having a problem with internal heating.  When I using an insulating bottom boundary and internal heating, the mantle will only heat up to a point and then stay at the same temperature.  This is most obvious when I'm using temperature dependent viscosity, as the system doesn't start convecting, and I can see the mantle stop heating up.  When I use Q=10, the mantle reaches a max temperature of about 0.75 and then stays there.  I tried using a higher Q, Q=30, but here the mantle heats up to a temperature of 1, with a small boundary layer to 0 at the top, and stays in this configuration.  These results are different than what I got using CicomCU, where the mantle would heat up beyond 1 and eventually start convecting, while here it appears to stop heating up and doesn't reach a point where convection starts. 

-Brad Foley