Jumping Bubbles in Foam

[themaxxer]

Hi there

I have another Problem i am struggling since a while. In some Scenes i am working on, Maybe a River, Beer Simulation or something else, when i increase the SPF above 6 the Foam Bubbles, the bigger ones begin to jumo out of the Fluid. I tried many Situations, lowering and increasing the SPF, the Viscosity, the Surface Tension, the Non Newtonian Value. I tested several B2B Situations, lowered and inreased the Rising Speed. The Thing is, i would like to stay with a Rising Speed for Foam around 80-90 and a B2B Interaction of around 400. All of this for a Highend Sulation. Any Ideas?
I am working with the Version 3.14 Nightly Build.

Kind Regards David

[Svetlin.Nikolov]

This likely happens because of too high B2B - you should not try to keep it high if it creates issues for you. Can you check if lowering the B2B would resolve this?

[themaxxer]

I tried it already with several B2B Values from around 1, 10,100 to 1000 i always got this Bubbles Jumping out of the Fluid. It seems like only the bigger Bubbles are affected. I followed the Beer Tutorial wich works with a B2B of 3000. My Goal is to achieve Foam with those very small Bubbles mixed with some larger Ones, like in Beer or Coffee Foam. I upload my Scene to you that you can check it.

Cheers

[Svetlin.Nikolov]

The beer tutorial is made with settings for the grid liquid solver of Phoenix 2. Phoenix 3 uses a new FLIP solver for liquids, so it does not need such a huge value for B2B.

[themaxxer]

https://www.dropbox.com/s/cb7pent6gl...eview.avi?dl=0

This is the Link to the Situation i am struggling with. B2b is now 280, but i tried lower Values with the same Problem. SPF of 12

[themaxxer]

https://www.dropbox.com/s/a0wc5jsnes..._2020.max?dl=0

and here is the Scene. i hope you can help. Thank you.
Cheers...David

[georgi.zhekov]

Hey,

Your rising and falling speed were really high for such a small scale scene so I reduced them quite a bit. I lowered the b2b to like 100 and now it looks a lot better in my opinion. Playing around with those settings should help you achieve the result you're after.

Cheers,

[themaxxer]

Ok, thank you for your help. i will try to sim this Scene with your Specifications. Ist important to me to understand how Phoenix FD works… So all those Values are Scene Scale dependend, as i learned, by raising the Density of the Grid i also have to increase the Viscosity, this is from my Honey Preset Question i posted here. When i work in a Beer Scene in real Scale, then Values wich worked for a River Scene want work here, do you know what i mean?

Cheers

[Svetlin.Nikolov]

Actually working in real world scale can only help you - for example, in both a beer setup and a river setup, you would not want the bubbles to rise at 3 meters/second, so you'd set the foam rising speed to 30-40 cm/second. Same goes for falling speed - you can use the same value for both beer and river. The difference is in the settings which are related to the balance between speed and quality of the simulation, such as steps per frame, conservation quality, viscosity, etc - the ones which are not in world units in 3ds Max's interface. I hope this makes sense and helps you look at the parameters in simple terms.

[themaxxer]

https://www.dropbox.com/s/cb7pent6gl...eview.avi?dl=0

[themaxxer]

As you can see in the Movie, it doesnt work in my Scene. I took the exact same Values wich you took for the Foam Situation. I saw it in the attached Picture. It works for About 40 Frames, after that, the same Problem. Any Idea?

[georgi.zhekov]

Indeed I have simmed only the first 40 frames in here.
So in order to improve the result - you can dial down the falling and rising speed even further.

Another thing you can do is to reduce the foam amount a bit and increase the birth threshold. In your scene the liquid is moving really fast and it's creating a lot of foam, which is bounced around from the fast moving liquid particles.