Trying to get viscous fluids to stick

[Steve_Green]

Hi,

I've been asked to simulate a spot being squeezed in slow motion, and a requirement for it to hit the 'camera'

I'd like it to be fairly viscous and not run down the surface, but whenever the fluids hit it, they seem to keep spreading more than the volume of the droplet, and I'm finding it hard to make them not spread as much and stick.

I do have frost, so I'm thinking maybe PhoenixFD isn't the best way to do it, and I should do it the old fashioned way with pflow?

Thanks,

Steve

[Ivaylo Katev]

try the flip solver in the nightlies, it is particle based, this means it keeps the liquid quantity and it has stronger viscosity and ability to stick to objects. if you hit some troubles we can send you fixed/modified builds in the same day.

[Steve_Green]

Great, thanks - have requested access.

[Steve_Green]

Had a bit of a play - finding the only way to get it to stick is to up the viscosity so much that the fluids are almost rigid, frozen into shape and sliding down the collision surface - maybe a world scale issue?

I take it there's no way to set friction on a collision object?

[Steve_Green]

https://www.dropbox.com/s/isqyj4ia5fre3fz/flip.avi?dl=0

Viscosity is set to .1 not sure why it's quite so stiff.

Tried scene scale of 1-10 doesn't seem to make much difference that I can see.

[Ivaylo Katev]

well, this is the nightly builds purpose to help us to achieve production quality before the release.
so, you need liquid to stay stuck to the wall even with low viscosity. actually the reason for the residual slow motion now is the lack of wetting control. we have wetting option, but the wetting is not implemented in the flip core. apparently it's time to implement it, hopefully in few days. if you are in rush, i can send you a build directly, to spare one day nightly builds waiting

[Steve_Green]

Hi,

it would be great if you could, thanks.

Also I'm not sure what level of stability I should expect - Max seems to hang fairly regularly, particulary when stopping a simulation, seems to happen more often when mesh is displayed in the preview but not really had that much opportunity to test exactly.

This is on Max 2013, Windows 7.

[Ivaylo Katev]

yes, the stability is lower of course, currently you can't render during a simulation, i think the pause operation is not 100% stable, the stop issue is new for me, but i don't use mesh preview and it can be related. it's good idea to save often and to avoid pause of the simulation.

[Steve_Green]

Thanks, yeah that's what I've been doing so far.

Cheers

Steve

[flipbook]

I find selecting the source helper and stopping the sim through that doesn't cause a crash. It crashes a lot when stopping through the simulator. Is there any news on friction/object sticking?

Thanks

[Ivaylo Katev]

what you mean with "stopping through the source helper" , is it just to stop the simulation when the source helper is selected?
the friction and stick are not implemented yet, perhaps they will be controlled by the wetting option.

[flipbook]

Yes I select the source helper then press stop, it's an extra step but better than crashing

[Ivaylo Katev]

helps to know that. but still is a mystery why it happens only with flip. it's sure that only flip is causing the crash isn't?

[flipbook]

I will try some tests with the old solver. Not used that in a long time ! Shall report back sometime this afternoon, got some proper work to do first :P

[flipbook]

Well, doesn't appear to crash on the normal solver.

I had a crash using the 'workaround' of stopping through the source helper just so you know, on the FLIP solver.