flame/

   A combustion-mode problem where we model a thermonuclear flame in a
   small domain.  This enforces the low Mach combustion constraint
   div{U} = S.  Hot ash and cool fuel are put into contact and a flame
   will ignite and propagate across the grid.  Inflow boundary
   conditions are used to allow for an inflow velocity to be set to
   keep the laminar flame stationary.

   An old/react_state.f90 exists in this problem averages the state
   laterally and calls the burner only on this 1-d average state.
   Since the flame is (should be) laterially invariant, this is an
   optimization to speed things up.

   Currently this problem has issues with high densities (> 5.e7
   g/cc).  Reducing the CFL number (to 0.1) helps.  Experiments with
   the SNe code show that SDC can overcome these problems.


sub_chandra/

   Surpise! We're modelling convection.  This time in 3D spherical
   in the helium shell on the surface of a sub-Chandrasekhar mass
   carbon/oxygen white dwarf.  Such systems can potentially yield
   a variety of explosive outcomes.  This setup is the basis for
   Zingale et al. 2013 (ApJ, 764, 97) and
   Jacobs et al. 2015 (ApJ, submitted)


toy_convect/

   A nova-like problem for studying convection.  This problem has seen
   extensive use in understanding which prediction types are the best
   when we have sharp species gradients.  See Mike Z or Ryan for
   details.


wdconvect/

   Model convection leading up to ignition in the Chandraseskhar-mass
   SNe Ia progenitor model.  This setup was the basis for Zingale et
   al. 2009 (ApJ, 704, 196), Zingale et al. 2011 (ApJ, 740, 8), and
   Nonaka et al. 2012 (ApJ, 745, 73).


xrb_mixed/

   Model convection in a H/He layer on a neutron star -- the early
   stages of a type I X-ray burst.  This setup was the basis for
   Malone et al. 2014 (ApJ, 788, 115) and Zingale et al. 2015 (ApJ,
   807, 60).
