[Bf-committers] Patch: Adaptive time step for fluid particles

michael fox mfoxdogg at gmail.com
Tue Jun 7 05:10:43 CEST 2011


I have done a little test using this already
http://vimeo.com/24544354

and yes if you keep the same value the results are predictable and
consistant

On Tue, Jun 7, 2011 at 12:13 PM, Matt Ebb <matt at mke3.net> wrote:

> What he means is that if you run two sims with the exact same settings,
> will
> the results be exactly the same? This is pretty important.
>
> cheers
>
> Matt
>
>
> On Tue, Jun 7, 2011 at 12:05 PM, Alex Fraser <adfries at vpac.org> wrote:
>
> > ----- Original Message -----
> > > From: "Shaul Kedem" <shaul.kedem at gmail.com>
> > > No, I mean is it deterministic?
> >
> > >From one run to the next, yes, you should get the same result.
> >
> > In terms of being predictable, I did some tests with the TwoPipe demo, in
> > which water drains through a hole (you may need to increase the fluid
> > interaction radius to see this effect). With zero subframes, it takes a
> long
> > time to drain; with more subframes, it tends to take less time (time in
> > frames, not computation time). However, it starts to converge for
> subframes
> > > 3 or a Courant target < 0.2, and barely changes beyond subframes = 8 or
> > Courant target = 0.1. So it seems to become more accurate with smaller
> time
> > steps, but you should rarely need to go beyond those values.
> >
> > The adaptive subframe code gives a stronger guarantee that your
> simulation
> > will be stable, but it's not predictive, so for some simulations a
> constant
> > time step is still more appropriate.
> >
> > Cheers,
> > Alex
> >
> > --
> > Alex Fraser
> > Software Engineer
> > The Victorian Partnership for Advanced Computing
> > _______________________________________________
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> > Bf-committers at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-committers
> >
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