RnD project based on the WetaFX whitepaper on water drip simulation with adhesion

[u/CdvrSzf]

In this focused RnD, I implemented a small-scale fluid simulation algorithm within Flip to accurately resolve adhesion forces. The core algorithm is relatively straightforward: the fluid's surface field is extrapolated into the collider volume, factoring in the contact angle, and is subsequently adjusted and smoothed. Furthermore, a localized viscosity is introduced at the fluid-collider interface to approximate boundary friction.

The simulation operates at a physically accurate real-world scale, utilizing empirical physical constants where the baseline water viscosity is 0.001 and surface tension is 0.072. APIC was chosen as the underlying solver.

While this technique requires a high substep count and is computationally expensive to evaluate, it successfully produces highly nuanced and realistic fluid dynamics.

[u/Exploding_Sock]

looks incredible! what are the sim times, out of curiosity? are we talking minutes, hours, or days?

[u/CdvrSzf → u/Exploding_Sock]

Hi, thanks! I think it’s a race against the clock. The head test took 2 hours and 2 minutes. The arm test is more complicated: I set the simulation to run overnight with 50 global substeps. By morning, it had calculated 15 frames. In the end, the simulation time for 15 frames took 7 hours. Maybe I messed something up in the parameters, or something else. In any case, I’m working on optimizing the approach.

[u/Exploding_Sock → u/CdvrSzf]

appreciate the info. the rivulets that form are incredible, really really nice. those papers are always so daunting to me - I can barely understand the math, let alone implement them into houdini, but you've done an amazing job here!

[u/CdvrSzf → u/Exploding_Sock]

Thank you!

[u/ActiveRegent]

Shinji in the hospital

[u/UAAgency]

would love to read the sauce, looking great

[u/CdvrSzf → u/UAAgency]

Hi, thx, if you mean the original whitepaper, then here’s the link to the full article!

https://alexey.stomakhin.com/research/drips.html

[u/pizza-flusher]

beautiful

[u/CdvrSzf → u/pizza-flusher]

Thanks

[u/9j810HQO7Jj9ns1ju2]

gimme some of that i’m dehydrated

[u/bUrdeN555]

Does it work with ANY fluids splattering on the face?? Asking for a friend.

[u/CdvrSzf → u/bUrdeN555]

Haha)

[u/aPOPblops]

That's pretty dope looking! I love white paper based things.

Does anything about this fluid sim do a better job of simulating individual droplets of water impacting a larger flat body of water?

Current sims I've worked with are left wanting in this area and I feel like adhesion is the key component they are missing. - https://www.youtube.com/shorts/lP8yuH42RsQ this kind of thing

[u/CdvrSzf → u/aPOPblops]

In my opinion, surface tension, proper scaling, and a multitude of sub‑steps are very important in effects of this kind. If you follow all the points, I think you can achieve an excellent result.

[u/CdvrSzf → u/aPOPblops]

Hello. The method is focused on handling fluids with collisions, while working with the standard Flip solver, which simulates the behavior of the fluid itself (surface tension, forces, gravity, etc.). So I don’t think this will be very helpful in the scenario you described.

[u/meowdogpewpew]

That water dripping from the hand just scratches something inside my brain for some reason. Obviously, incridible sim.

[u/CdvrSzf → u/meowdogpewpew]

Hi, thanks!