[Sidefx-houdini-list] Flipping viscosity

nicholas pliatsikas nicholas.pliatsikas at gmail.com
Wed Sep 21 10:24:46 EDT 2011


Yeah flip in h11 isnt a one fits all solution, defo has its limitations in
its current state.
Sph is much more robust and reliable but so much slower, so much so I wrote
a maya nparticle geo exporter at one point as the guys here where able to
get better results quicker in some cases.
H12 im sure will change everything!! have fun with realflow :¬) (i have a
love hate relationship with it to be honest)
Cheers
Nick




On Wed, Sep 21, 2011 at 3:14 PM, andy at andynicholas.com <
andy at andynicholas.com> wrote:

> Thanks for the info Nick. Yes, I've been having the same issue with the
> friction
> that you mentioned.
>
> So yes, it seems to be a bit of a non-starter really. I'm currently testing
> stuff in Realflow, and it's got everything I need, as well as generally
> being
> slightly faster. So it would seem that that's gonna have to be the weapon
> of
> choice on this one. I've got no time to sit and try and reverse engineer
> DOPs
> (and don't even get me started about the lack of documentation for
> that!!).
>
> (BTW, despite frustrations with DOPs, I am starting to feel a little more
> comfortable setting up custom stuff, but I'd love to know if anyone has
> what
> they'd consider to be the "definitive" resource for it.)
>
>
> Roll on Houdini 12 is all I'm gonna say. The speed ups are gonna be a real
> game
> changer for getting into this :)
>
> Cheers!
> Andy
>
>
>
>
> On 21 September 2011 at 15:02 nicholas pliatsikas
> <nicholas.pliatsikas at gmail.com> wrote:
>
> > Its the same in most companies ;¬) No worries.
> > Anyhoo I hope that stuff helps you Andy. One other thing that was
> > problematic on flip was the stickyness or lack of it when hitting other
> > objects, so the fluid tends to slide and fall off anything that moves in
> an
> > unnatural way. Friction was also problematic... Not sure if we worked
> around
> > it in the end.
> > Cheers
> > Nick
> >
> > On Wed, Sep 21, 2011 at 2:34 PM, Nick Zutphen <nvanzutphen at live.com>
> wrote:
> >
> > > Hi Nick,
> > >
> > > Well I'm not allowed to talk about any of that, I'm sorry.
> > >
> > > If you intern with a R&D company like SideFX, you have to sign a NDA
> (non
> > > disclosure agreement). Which basically says: you can't talk publicly
> about
> > > anything you read, hear, see or smell (:p) within the walls of the
> office.
> > > Such an agreement last for an x period of time, I guess a year after
> your
> > > contract ends. It's due to protect the intellectual property of a
> company
> > > like SideFx, especially when it comes down to competitors. This makes
> sense
> > > to me.
> > >
> > > Cheers,
> > > Nick van Zutphen
> > > ----
> > > http://www.nickvanzutphen.com
> > >
> > > On Sep 21, 2011, at 2:21 PM, nicholas pliatsikas wrote:
> > >
> > > > Nice one Nick van Zutphen !! ;¬) Did you come up with fix too?
> > > > Cheers
> > > > Nick
> > > >
> > > > On Wed, Sep 21, 2011 at 12:58 PM, Nick Zutphen <nvanzutphen at live.com
> >
> > > wrote:
> > > >
> > > >> Hi Nick!
> > > >>
> > > >> I just had a look at the file that you shared and I figured it
> looked
> > > very
> > > >> familiar to me. Turns out, I made this file during my internship
> with
> > > SideFX
> > > >> in Toronto last summer :p. When I started writing this email I
> suddenly
> > > >> remembered that at  some point I was in contact with a 'Nick'.
> > > >>
> > > >> Cheers!
> > > >> Nick van Zutphen
> > > >> ----
> > > >> http://www.nickvanzutphen.com
> > > >>
> > > >> On Sep 21, 2011, at 1:41 PM, nicholas pliatsikas wrote:
> > > >>
> > > >>> Hey andy
> > > >>> Ok there where various fixes that we came across and sidefx also
> sent
> > > >>> heres one for surface tension
> > > >>>
> > > >>
> > >
> http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=20359
> > > >>>
> > > >>> and the text from me to sidefx support regarding this
> > > >>>
> > > >>> Anyways Id like to put an rfe/bug report in for the flip fluid
> solver.
> > > >> After
> > > >>> some tests it seems that surface tension, viscosity and friction
> dont
> > > >> work
> > > >>> at all on the flipfluid solver, im thinking that they havent been
> > > >> implement
> > > >>> rather then they dont work.
> > > >>>
> > > >>> Theres a wee thread on sidefx.com regarding some of this.
> > > >>>
> > > >>> http://www.sidefx
> > > >>> .com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=20359
> > > >>>
> > > >>> The surface tension can be added to the flip solver very easily
> using a
> > > >> gas
> > > >>> surface tension microsolver. So im guessing it should be pretty
> easy to
> > > >>> integrate correctly into the flip setup.
> > > >>>
> > > >>> For viscosity, we tried gasblur on velocity etc but this messes
> with
> > > >> general
> > > >>> velocity to an extent it slows down the fluid as whole, for example
> the
> > > >>> fluid would look like its floating as gravity doesnt have the same
> pull
> > > >> on
> > > >>> it due to blurred velocity.
> > > >>> Sidefx sent me a better solution, Ive uploaded the file sent to me
> with
> > > a
> > > >>> better working viscosity, i cant quite recall what the changes
> where
> > > off
> > > >> the
> > > >>> top of my head.. but i do think there where some notes in the file.
> > > >>>
> > > >>> http://www.mediafire.com/?t1u8ts2gnntb1vp
> > > >>>
> > > >>> Either way sidefx informed me that these issues should be solved in
> the
> > > >> next
> > > >>> houdini version.
> > > >>>
> > > >>> Hope that helps
> > > >>> Cheers
> > > >>> Nick
> > > >>>
> > > >>> On Wed, Sep 21, 2011 at 11:25 AM, andy at andynicholas.com <
> > > >>> andy at andynicholas.com> wrote:
> > > >>>
> > > >>>> Hi Nick! Thanks a lot, much appreciated :)
> > > >>>>
> > > >>>> Cheers,
> > > >>>> Andy
> > > >>>>
> > > >>>>
> > > >>>> On 21 September 2011 at 10:28 nicholas pliatsikas
> > > >>>> <nicholas.pliatsikas at gmail.com> wrote:
> > > >>>>
> > > >>>>> I had the exact same problem, i ended up contacting support about
> > > this
> > > >> as
> > > >>>> it
> > > >>>>> really became a big limitation. Let me do a wee search through my
> > > email
> > > >>>> and
> > > >>>>> will pass you the relevant information.
> > > >>>>> Cheers
> > > >>>>> Nick
> > > >>>>>
> > > >>>>> On Tue, Sep 20, 2011 at 10:50 PM, andy at andynicholas.com <
> > > >>>>> andy at andynicholas.com> wrote:
> > > >>>>>
> > > >>>>>> Hi all,
> > > >>>>>> I have a feeling I know what the answer to this'll be, but I
> need to
> > > >>>> ask
> > > >>>>>> just in
> > > >>>>>> case... does anyone know if there's any way of getting FLIP
> fluids
> > > to
> > > >>>>>> exhibit
> > > >>>>>> some sort of viscosity?
> > > >>>>>>
> > > >>>>>> I've had a quick play with SPH and the speed (or lack of) means
> that
> > > >>>> it's
> > > >>>>>> not
> > > >>>>>> really an option. FLIP is so much faster, but I'm just lacking
> the
> > > >>>> control
> > > >>>>>> over
> > > >>>>>> the thickness that I need to achieve. Anyone tried any POP or
> SOP
> > > >>>> solver
> > > >>>>>> hacks
> > > >>>>>> to get this effect?
> > > >>>>>>
> > > >>>>>> Any pointers gratefully received.
> > > >>>>>>
> > > >>>>>> Thanks :)
> > > >>>>>>
> > > >>>>>> Andy
> > > >>>>>> _______________________________________________
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> > > >>>>>>
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