[FLASH-BUGS] Bug in quadratic_cartesian interpolation scheme?

[Robi Banerjee]

Hi Mike,

  I have set up a web page showing the outcome of the quadratic_cartesian
interpolation scheme compared with the old second order one. You can
find the page at: 
http://physwww.physics.mcmaster.ca/~banerjee/problem.html

  I used FLASH 2.3 on our Alpha with Tru64 Unix. I initialized the
the data with a simulation done with Zeus, therefore it is not easy
for me to rewrite the code for a 2D simulation. Here are some more
information of the modules I used:

REQUIRES driver/time_dep
REQUIRES hydro
REQUIRES gravity/poisson/multigrid
REQUIRES materials/eos/gamma
REQUIRES source_terms/cool/radloss
REQUIRES mesh/amr/paramesh2.0


  The 'stripes' appear in all variables but are most prominent
in the velocities. Maybe the 'stripes' show up only in regions
with a large gradient of the variables?

  Robi


On Wed, 5 Nov 2003, Mike Zingale wrote:

> Hi Robi, the only problem that I am aware of with those prolongation
> routines is that the monotonicity constraint does not operate on the mass
> fractions as a whole, so it does not guarantee that they sum to one at the
> end -- this is something that I've been meaning to fix, but have not had
> the time.  
> 
> I have not seen a problem like you describe.  More information would be
> useful -- especially if you could reproduce the problem in 2-d, as it
> would be easier to debug then.
> 
> Mike
> 
> ------------------------------------------------------------------------------
> Michael Zingale
> UCO/Lick Observatory
> UCSC
> Santa Cruz, CA 95064
> 
> phone:  (831) 459-5246 
> fax:    (831) 459-5265
> e-mail: zingale at ucolick.org
> web:    http://www.ucolick.org/~zingale
> 
> "Once something has been approved by the Government, It's no longer immoral."
>    -- Reverend Lovejoy
> 
> 
> 
> 
> 
> 
> 
> On Wed, 5 Nov 2003, Robi Banerjee wrote:
> 
> > Hi,
> > 
> >   I ran into a problem (non convergence in the Riemann solver)
> > using the new 'quadratic_cartesian' interpolation scheme in a
> > 3D simulation including selfgravity. 
> >   Looking into the details after a refinement step I figured 
> > that the data in the newly refined blocks develop stripe-like
> > structures. This leads, for instance, to overshooting in 
> > velocities, resp. mach numbers. 
> >   Using the old interpolation scheme (second_order_old) 
> > everything is fine and the variables are smoothly prolongated 
> > onto the newly refined blocks.
> > 
> >   Is this a known problem, or is there a problem with the
> > new (quadratic_cartesian) interpolation scheme?
> > 
> >   If you need more information, please don't hesitate to
> > ask for (e.g. 2D slices of the simulation data with the
> > two different interpolations schemes)
> > 
> >   Thank you,
> > Robi
> > 
> > ====================================
> > Robi Banerjee
> > Department of Physics and Astronomy
> > ABB-320, McMaster University
> > Hamilton, ON L8S 4M1
> > CANADA
> > e-mail: banerjee at physics.mcmaster.ca
> > phone : (905) 525-9140 x 23189
> > fax   : (905) 546-1252
> >  
> > 
>