[FLASH-USERS] Numerical Effects in Spherical Coordinates

[Klaus Weide]

On Thu, 23 Mar 2017, Jason Galyardt wrote:

> Also, you mention that the gas might be bouncing off the inner boundary:
> are your boundary conditions reflective, then? If not, there will be no
> bouncing; if so, turn the boundary conditions to 'outflow' and see what
> happens.

The reflecting boundary condition (in R-direction) at 0, by itself, should 
not cause a problem.

I am more concerned about the reflecting boundry conditions in the 
"y"-direction: The domain consists of a subrange of angles,

   75\deg <= \theta <= 105\deg ,

and applies "reflecting" boundaries at 75 and 105 degrees.

FLASH allows you to do this, but the implementation of boundary conditions 
does not take into account that "y" is a 3D polar angle and therefore may 
be inappropriate.

I wonder whether the same problems would show up in 2D "polar" coordinates
with a similarly limited angle.


Also, the number of blocks varies a lot, and may not even have converged 
during Grid initialization.
Maybe not all of the following four should be used:
refine_var_1                = dens                           [CHANGED]
refine_var_2                = velx                           [CHANGED]
refine_var_3                = pres                           [CHANGED]
refine_var_4                = temp                           [CHANGED]


Klaus