[FLASH-BUGS] was there a signbificant bug fix for hydo

[Mike Zingale]

> I was opting for numerical diffusion at first, but the pattern does not seem 
> to make sense. Maybe it is originating from corners at the individual blocks 
> ... Using more blocks gives me more ripples and the amplitude is not 
> significantely reduced ...

Markus, you can test whether this is arising at the corners of the
individual blocks by running at the same resolution, but with larger
blocks.  The default is 8x8x8, but try running with 16x16x16, using
-nxb=16 -nyb=16 -nzb=16 on your setup call.  You will want to drop the
number of levels of refinement down by one so you still retain the same
resolution.  If you have the same number of ripples, then it is likely not
a block boundary problem.  You may have to reduce maxblocks some, but you
will probably see better overall performance with these larger blocks.  I
am not aware of any block boundary problems that we've fixed recently.

The problem may simply be the result of having a circular flow represented
on a Cartesian grid, which will introduce ripples from approximating the
circle as a sequence of squares.  Going to a finer resolution would give
finer stair-step approximations to your flow.

Mike




> 
> I am still using FLASH2.1, so my question is basically: did you fix something 
> which could cause such an effect?
> 
> Many thanks for your time! I will do my best to try to upgrade to 2.3 when it 
> comes out.
> 
> 
> Markus.
> 
> 
> -- 
> _______________________________________________________________
> 
> Markus Gross AMIMechE BEng (Hons.) Mechanical Engineering
> 
> Heriot Watt University Edinburgh
> Department of Mechanical and Chemical Engineering
> 
> Associate member of the Institution of Mechanical Engineers
> Member of the SPIE
> _______________________________________________________________
> 
> further contact:
> 
> Phone   : +44 (0) 131 449 5111 etx. 4737
> 
> UNiX talk: talk markus at lasersim.mce.hw.ac.uk
> 
> _______________________________________________________________
> 
> "Plans are a place to begin," Grove said. "They rarely deliver
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> _______________________________________________________________
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