[FLASH-USERS] Coupling RHD with self-gravity

[Klaus Weide]

On Thu, 5 Jul 2018, María Fernanda Clever Uribe wrote:

> I'm not sure I can use a periodic boundary condition. Could I use another
> solver like tree gravity instead?

I don't think so - the Barnes-Hut Tree solver in FLASH has this code
(in gr_bhInit.F90):

  ! Check if we support the requested grid geometry.
  if ((NDIM /= 3) .or. (gr_geometry /= CARTESIAN)) then
     call Driver_abortFlash ('[gr_bhInit] ERROR: tree Poisson solver works only in 3D Cartesian geometry')
  endif

The gravity solvers in FLASH all appear to be for threedimensional 
physics.  Some may be usable in 1D or 2D, but that is just the 
dimensionality of the numerical representation - the physics represented 
is still 3D (with some added assumption of symmetry, e.g., spherical).
So you can find a gravity solver for 1D spherical or 2D cylindrical, but 
not 1D or 2D Cartesian.

It isn't quite clear what 2D (physical) gravity is actually supposed to 
mean. (Try a Web search for "Gravity 2D"...) Just solving a 2D Poisson 
problem instead of a 3D one isn't quite enough!

Klaus