[FLASH-USERS] FLASH2 -> FLASH3/4 Viscosity

[Klaus Weide]

On Sun, 8 Apr 2012, Dan D'Orazio wrote:

> Hi,
> 
> I noticed the following publication in the new Publications compilation:
> 
> Edgar, R.G.
> An alternative approach to viscosity in an accretion disc
> http://adsabs.harvard.edu/abs/2006astro.ph..9756E
> 
> This was published while FLASH 2(.5) was the current release. I was
> wondering if this scheme was implemented in the FLASH 3 (held over to
> FLASH4) release.

Dan,

I believe that the inplementation in Diffuse_visc.F90 in 
FLASH4-{alpha,beta}, as well as FLASH3.3, is intended to be equivalent to 
the "alternative approach" of Edgar.  However, I have not done a 
term-by-temp comparison now; and to my knowledge the current 
implementation has not been tested in polar coordinates.  I recommend you 
examine the code in Diffuse_visc.F90 yourself to see whether it is 
equivalent to Edgar's approach.

Note that with the unsplit Hydro (or MHD) solver, the relevant 
implementation is not Diffuse_visc.F90 but hy_uhd_addViscousFluxes.F90.

> More generally, are the main changes to the Diffuse_visc routine from
> FLASH 2 to FLASH 3 documented anywhere?

Not to my knowledge, but the current Diffuse_visc.F90 seems to have 
changed so much from FLASH2 that it is essentially a new implementation.

Klaus