Underwater impact splash

[malik]

Hi!

I'm trying to achieve something looking more or less like that: https://vimeo.com/13553804

I tried many ways, without getting even remotly close to what I'm looking for.

Any thought be welcome.

Thanks in advance.

[shawn_kearney]

TOTAL guess here, but what if you emitted pyro from the object and use that to advect through a flip tank?? This kind of disturbance comes from an pocket of air, so I am thinking that something like that might work.

[malik]

Thanks Shawn, very good idea, I'll qivr it a try.

[Atom]

That is interesting Shawn. Say I have a flip tank and a sphere on fire that I have created with shelf tools. How to I link them as you describe? What tool would I use to combine the two sims? Merge Sims?

Edited December 3, 2016 by Atom

[shawn_kearney]

I'm not 100% sure, though I do have some ideas to try once this semester is over. I don't know if I could get it to work in just one DOP.

Another thing I've done to get bubbles, and wasn't thinking about cavities when I posted, is emit fluid particles with a density of air (1.225 kg/m^3) inside a tank with a density of 1000 kg/m^3. For this I animated the emission rate on and off to get bubbles on and off. I then converted both to SDF surface volumes and did an SDF difference merge from the tank. A continuous stream of particles, or one whose emission rate is regulated by velocity of the RBD object might work to produce this kind of streaming cavitation. 

That'd probably be a better solution, really. Lately I've been pre-occupied with driving simulations with pyro, and was probably stuck thinking that way. But I do think it COULD be done. One issue though is that pyro sims want to expand, and it'd seem that cavities like this want to collapse.

[shawn_kearney]

@Atom @Malik I was able to get some basic cavitation to work using pyro. What I did was advected the the flip tank using POP Advect Volume and pointing to the Pyro sim's DOP I/O SOP. That made for some interesting churning, but the cavity still was not forming. So I took the resulting FLIP particles and used Attribute from Volume from the Density field. I then deleted flip particles less than this value and isolated both the tank particles and the cavity particles.

I then took the flips and surfaced each into an SDF volume and used SDF Difference to combine the two volumes using VDB Combine SOP. I found that this was needed in order to maintain features that lack congruency within the tank.

It does work, but the pyro simulation does not look right. I used whispy smoke, but flames might work better and I am not 100% up to speed with pyro yet. But I think with the right settings it should work. Also fuel should probably be scaled to the magnitude of the velocity vector (not hard, just didn't do it).

 

cavitation.hiplc

Edited December 5, 2016 by shawn_kearney

[malik]

Thanks for sharing Shawn I'll give it a look today.

[zinogino]

Thanks for sharing the hip file. Definitely helped me in achieving water drop impact shot as well.
I initially did a small test run by faking the effect with a timed pyro sim from the animated geo and it does work but seems like combining with an actual flip tank yields better results.

*Initial test with pro*