Vortex structure of flow around a cube.  Not happy with it since it's
begging for scattering, but I thought I'd plug the simulation results in to
POV-Ray and get something pretty.  This took a while, so I might never get
around to animaing the other 199 frames.  Seemed worth sharing.

- Ricky

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Attachments:
Download 'test2.jpg' (86 KB)

Preview of image 'test2.jpg'

"triple_r" <rre### [at] hotmailcom> wrote:
> Vortex structure of flow around a cube.  Not happy with it since it's
> begging for scattering, but I thought I'd plug the simulation results in to
> POV-Ray and get something pretty.  This took a while, so I might never get
> around to animaing the other 199 frames.  Seemed worth sharing.
>
> - Ricky

This looks neat--but maybe you could explain what you mean by "vortex
structure of flow"?  Just curious--sounds interesting.

-- Kirk

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It's explaned in the following link somewhere in the middle, but it
basically amounts to the vorticity minus the shear, leaving the rotation.
Not my paper of course, but I just tried (unsuccessfully) to replicate the
results.  I couldn't get mine even close to turbulent.

http://www.bgu.ac.il/~yakhot/homepage/publications/JFM_2006.pdf

Say, does anyone know how to get decent render times out of good-looking
media?  Method 3 tends to give me 'slices' and Method 2 needs too many
samples.  Here are my current settings for a smokey-looking wake, but it's
taking quite a while.  Maybe that's to be expected.

media {
  method 3
  intervals 30
  ratio 0.9
  samples 4,4
  jitter 1.0
  aa_level 3
  aa_threshold 0.05
  emission <1,1,1> * 8
  absorption <1,1,1> * 2
  scattering {
    1, <1,1,1>*10
    extinction 2.5
  }
  confidence 0.99
  variance 1/100
  density {
    density_file df3 "output.df3"
    interpolate 1
    color_map {
      [0.0 rgb 0]
      [1.0 rgb 1]
    }
  }
}

 - Ricky


"Kirk Andrews" <kir### [at] hotmailcom> wrote:
> "triple_r" <rre### [at] hotmailcom> wrote:
> > Vortex structure of flow around a cube.  Not happy with it since it's
> > begging for scattering, but I thought I'd plug the simulation results in to
> > POV-Ray and get something pretty.  This took a while, so I might never get
> > around to animaing the other 199 frames.  Seemed worth sharing.
> >
> > - Ricky
>
> This looks neat--but maybe you could explain what you mean by "vortex
> structure of flow"?  Just curious--sounds interesting.
>
> -- Kirk

Post a reply to this message

"triple_r" <rre### [at] hotmailcom> wrote:
> It's explaned in the following link somewhere in the middle, but it
> basically amounts to the vorticity minus the shear, leaving the rotation.
> Not my paper of course, but I just tried (unsuccessfully) to replicate the
> results.  I couldn't get mine even close to turbulent.
>  ...
>  - Ricky
>
>
> "Kirk Andrews" <kir### [at] hotmailcom> wrote:
> > "triple_r" <rre### [at] hotmailcom> wrote:
> > > Vortex structure of flow around a cube.  Not happy with it since it's
> > > begging for scattering, but I thought I'd plug the simulation results in to
> > > POV-Ray and get something pretty.  This took a while, so I might never get
> > > around to animaing the other 199 frames.  Seemed worth sharing.
> > >
> > > - Ricky
> >
> > This looks neat--but maybe you could explain what you mean by "vortex
> > structure of flow"?  Just curious--sounds interesting.
> >
> > -- Kirk




Oops, I top-posted.  Sorry.

 - Ricky

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Hash: SHA1

triple_r wrote:
> It's explaned in the following link somewhere in the middle, but it
> basically amounts to the vorticity minus the shear, leaving the rotation.
> Not my paper of course, but I just tried (unsuccessfully) to replicate the
> results.  I couldn't get mine even close to turbulent.
> 
> http://www.bgu.ac.il/~yakhot/homepage/publications/JFM_2006.pdf
> 
> Say, does anyone know how to get decent render times out of good-looking
> media?  Method 3 tends to give me 'slices' and Method 2 needs too many
> samples.  Here are my current settings for a smokey-looking wake, but it's
> taking quite a while.  Maybe that's to be expected.
> 
	First thing first, try:
intervals 1
samples 120

	This should be faster and give better results than your settings.
Then, try to play with the samples (only one number has meaning with
method 3), but *keep the intervals at 1*.

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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Version: GnuPG v1.4.7 (GNU/Linux)

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triple_r nous apporta ses lumieres en ce 23-04-2007 10:05:
> It's explaned in the following link somewhere in the middle, but it
> basically amounts to the vorticity minus the shear, leaving the rotation.
> Not my paper of course, but I just tried (unsuccessfully) to replicate the
> results.  I couldn't get mine even close to turbulent.

> http://www.bgu.ac.il/~yakhot/homepage/publications/JFM_2006.pdf

> Say, does anyone know how to get decent render times out of good-looking
> media?  Method 3 tends to give me 'slices' and Method 2 needs too many
> samples.  Here are my current settings for a smokey-looking wake, but it's
> taking quite a while.  Maybe that's to be expected.

> media {
>   method 3
>   intervals 30
>   ratio 0.9
>   samples 4,4
>   jitter 1.0
>   aa_level 3
>   aa_threshold 0.05
>   emission <1,1,1> * 8
>   absorption <1,1,1> * 2
>   scattering {
>     1, <1,1,1>*10
>     extinction 2.5
>   }
>   confidence 0.99
>   variance 1/100
>   density {
>     density_file df3 "output.df3"
>     interpolate 1
>     color_map {
>       [0.0 rgb 0]
>       [1.0 rgb 1]
>     }
>   }
> }

>  - Ricky




When using method 3, intervals >1 is a NO-NO.
Leave it at 1 and increace samples, MUCH faster!

-- 
Alain
-------------------------------------------------
My toes were playing the piano under the blankets.
They made so much noise that I woke up singing.

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> When using method 3, intervals >1 is a NO-NO.
> Leave it at 1 and increace samples, MUCH faster!
>
> --
> Alain

Thanks for the advice.  Seems to work even if the colors are a little dull.
It was faster though.  I guess inefficiency is what you get for
once-every-couple-months pov-ing.  As for an animation, that still may take
a while.

 - Ricky

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Attachments:
Download 'qvol2.jpg' (41 KB)

Preview of image 'qvol2.jpg'

The first version was pretty, but this one is genuinely cool. Now the 
media feels genuinely 3D.

-- 
William Tracy
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|w|t|r|a|c|y|@|c|a|l|p|o|l|y|.|e|d|u|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
You know you've been raytracing too long when you boot up in the morning 
and your computer has a message waiting for you that says "Come on buddy 
get a life !".
Ken Tyler

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triple_r wrote:
>>When using method 3, intervals >1 is a NO-NO.
>>Leave it at 1 and increace samples, MUCH faster!
>>
>>--
>>Alain
> 
> 
> Thanks for the advice.  Seems to work even if the colors are a little dull.
> It was faster though.  

...and with the greater volumetric effect, it's much more illustrative.

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Do plan on sharing your code, or at least do a large render?  I wouldn't
mind this as a desktop bg.

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