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Water inside of air field

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A hip file just with a simple scene would greatly help all of us here to understand the concept.

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I don't think that will cut it, as we would like to have the larger scale motion of the air affecting our fluid.

Check it out: https://vimeo.com/60134752

Air is added only where it's needed basing on sdf of main fluid.

Looks like I'll just have to eat my words, now =)

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This looks really good! Any more info on how to set this up? I just started learning Houdini a few weeks ago, and I can't really figure out where to start with this. Any pointers?

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I seem to be getting a hang of it. but I get to much mixing at the boundaries, like air is not rising up from inside the water fast enough and causing very noisy boundry between water and air. I wonder If you have used a sop solver to mix the trapped air particles into water particles ????

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Thanks for your share.I have tried this effect following your thought. But what I got is different. I noticed that some of your particles are floating in the air. Even if I give 0 to the parameter of the density of particles in the air, My particles also drop down . Did you control the graviety to get that effect? I love that effect very much.Please help me.

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Ok I've got this working with a sop solver grabbing the surfaceField and scattering points with zero density in it, thats fine.

But seeing as density is a field and it's a just splatting the density point attribute into the field I thought I'd have a go at just doing it with gas microsolvers.

I'm a bit tired (well past midnight here) so my apologies if it's something glaringly obvious, but I can't get it to work. I've made a new field "mydensity" and copied the "massdensity" values to it, normalized them by finding the min and max, bit of a blur, vop to pull in the region a bit, then multiplied the "massdensity" field by the "mydensity".

This should work by the look of things, but obviously I'm missing something.

Thanks for any help

C

airField_gasMicro_v001.hip

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Messed around for an hour with this, based off of Christian's scene, got something approaching the effect but it isn't quite beautiful (and it's pretty slow). Still, you can see the general idea of seeding air particles. Plenty of work still to be done. 12.5 only, was messing with the VDB nodes a bit. Maybe this will be helpful to people.

air_flip_interaction.hipnc

Edited by Bonedaddy

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Took me a while to figure out exactly what exactly people were trying to do, and then considerably longer to find a suitable way of doing it, but I've attached a file with a very basic control for getting the air effects on water. I wouldn't pay much heed to the surfacing I've applied to them, it was more for a better visual comparison, but the fluid is certainly behaving in a much nicer pattern by controlling the density.

It's a basic fliptank, and on the initial fluid there's an attribute density created where any particle above an arbitrary line is given the density of air (1.225), and everything below is given water density (1000). Then in the final result you simply delete the lower density particles before surfacing. I'm only relatively new to houdini so I don't know any particularly great ways of surfacing water, but this will at least give you the correct breakup on the surface.

For more dramatic effects you'll want to aerate the water more, which should be easily done with some turbulence in it's affecting forces.

Density.hipnc

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The question to be asked now is, can a similar effect be achieved in reverse wherein water surrounds air (bubbles)? My puny attempts at this have proven ineffective...

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The question to be asked now is, can a similar effect be achieved in reverse wherein water surrounds air (bubbles)? My puny attempts at this have proven ineffective...

Pretty easy using the density attribute + sop solver...

h12_5_Flip_Density_Bubbules.hip

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That's cool Ian.

The other approach to bubbles in the flow may be using reseeding in flip solver.

Playing with oversampling settings to get different sampling settings for the surface and interior of the fluid gives cavities as well.

That trick is working great in Naiad (https://vimeo.com/47556195 skip to the end of the video).

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Sorry to hijack the thread, but it seems here is all the talk about it. I came up with an idea out of the blue and tried it, adding airparticles around the fluid only where it's needed. It isn't perfect yet, but pretty good for an hours work:

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Nice man, what's the secret?  ;)  I can seem to get to work well unless I fill the entire container up.

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Guest tar

Ya - it's nice work but I'm not sure of the point of posting here it if the formula isn't shared. How does it help us?

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Nice man, what's the secret?   ;)  I can seem to get to work well unless I fill the entire container up.

Basically just creating particles around the surface field, which is an SDF, and deleting them at the end of each timestep. I just had a look at what I did yesterday, and while it worked, it was not very optimal at all - close to impractical in every way in terms of speed. I currently suffer from time constraints so it will probably be later rather than sooner, but I got some ideas how to make it a lot better. If I find the solution you might hear a faint whisper ;)

 

Ya - it's nice work but I'm not sure of the point of posting here it if the formula isn't shared. How does it help us?

It doesn't help you at all probably. But I can score some boring comments like that which puts one off sharing even more, which is always nice.

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Ok, that's actually what I was trying. I was close, though I didn't get it working in the right order quite right, and my surface and velocity field both ended up getting huge. I just need to figure out the source and delete placement I think.  Thanks!

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Ok, that's actually what I was trying. I was close, though I didn't get it working in the right order quite right, and my surface and velocity field both ended up getting huge. I just need to figure out the source and delete placement I think.  Thanks!

Yeah thats why you need to delete the air, otherwise the surface will grow. It's probably the very last thing you want to do, ie after your Gravity Force and whatnot :). Also, take a look at how the Source Volume DOP sources it's particles - that's where I initially got the idea from.

Edited by Skybar

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Guest tar

 

 

It doesn't help you at all probably. But I can score some boring comments like that which puts one off sharing even more, which is always nice.

 

100 / 100 people would want to know how you achieved this fx. That's a complement if you missed it!

 

I would be put off sharing if no-one wanted to know anything about it  ;)

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