Foam Bubbles "Variation Large" jump out of the Water

[Guest]

Hello everybody,
i know i posted this Question already a long Time ago i always struggle with the same Foam Issue/Problem... when i use the Variation Large Amount int the Foam i got those Foam Bubbles leaving the Mesh with to much Speed. Even if i use the Half Life "Vary" Button. You can trust me i tried so many Variations of Rising Speeds, Sizes, B2B interactions and SPF. My Goal is to achieve a Foam Volume with much different Sizes as you can see in the Image. I would like to see those "Black Holes" do you see what i mean? The Rising for the Average and small sized Bubbles must be enough to form those nice Foam Patterns on the Surface of the Water Body. In my Opinion it would be great to have more Control for the Foam. Something like biggest Bubbles stuck to every other Bubble. Another Thing i already tried could possibly the Solution. More SPF, but this takes all Turbulence out of the Sim, yes it is more stable but boring. Maybe someone can help. Thanks in Advance.
Kind Regards David

[Svetlin.Nikolov]

Use foam patterns to get the black holes. B2b to get the clunky strings. And use less rising speed or more steps per frame if your bubbles fly out of the liquid too fast

[Guest]

hi svetlin
thanks for your quick answer. as i explained above i already tried this. By black Holes i mean the Largest Bubble in the Foam Volume. The Largest Bubble itself should be big enough that i can see the Ground. This means i have Bubble Sizes vary from 0.16 to 0.5 in Variation Large. Even this Value is enough to speed up those Bubbles to shoot out the Mesh. I am satisfied with the Rising Speed and the SPF. So then i have to raise the SPF, but it happens with every Value. I can try the Foam Patterns but i think in my Scene it is not the right Thing. The Creek is only 80 Cm wide. Foam Patterns are for larger Simulations, right? When i change the Rising Speed the smallest Bubbles stuck to much on the Ground but i need this to fill the Water Volume/Mesh.

[Joelaff]

You can use two different Particle shaders to set two different sizes. That might help. Use two subgroups with greater than and less than a threshold size.

[Ivaylo Katev]

So, if i understand correctly, the core of the problem is that the large bubles are throwed away with latge speed from the main foam body? I would suggest that exactly the high b2b value may be the cause of the issue. You need only single bubble layer over the surface, not a thick volumetric foam like in a beer. Try to use as low as possible value of b2b, just to keep the bubbles from overlapping each other

[Svetlin.Nikolov]

I think it would be best if you attach the scene simulation setup you have up to this point here.

[Guest]

ivaylo Katev, yes that's exactly what i mean. If i use the the Variation Large Value this happens every Time. If i don't use it it works. So for Simulations this works, maybe? But what i tried to explain is that Water Foam has so many different Sizes and if i would like to render a Picture out of the Simulation i would like to see those bigger Foam Bubbles showing the, as i described it, Black Holes. I played a lot with different Distributions. Am i getting this right Distribution only works if i enable Variation Large? Wouldn't it be great to have the same Value for Variation Small? I filmed a lot of Reference Material of Creeks and Rivers and i learned that the Bubbles remain in the Water Volume/Body, so for that i have to have a lot of Small Bubbles and then they reach the Surface of the Main Water Body and form those nice Foam clunky Strings. In the Picture i attached, you can see what i mean.

Thanks for your Ideas Guys, i am trying to lower the B2B first resim it a few Times and look how it behaves. What has the Rising Speed of the Foam to deal with the shooting out of the Foam Volume? A Few Months back i tried to achieve Foam falling with the same Speed as Water Droplets or simulated Water Splashes in the Mesh. I found out that a Value of around 240 to 280 behaves like the Foam Bubbles behave like they are forced by Gravity. So then i thought this would be "the" Value to go.

[Guest]

Joelaff, thanks for your Input. I don't exactly know what you mean with your Suggestion?

[Ivaylo Katev]

But what i tried to explain is that Water Foam has so many different Sizes and if i would like to render a Picture out of the Simulation i would like to see those bigger Foam Bubbles showing the, as i described it, Black Holes.

Yes, i understood what you mean, the natural size distribution is like this, small count of large bubblesand big count of small bubbles, and the size variation algo is designed to produce exactly this behavior. The value of the "distribution"parameters controls how rare the big bubbles are. Do you have any problems to achieve the desired presence of large bubbles?

[Guest]

Hi Guys
After simulating the scene over and over again, I realized what my mistake was, namely, I always started with the middle foam bubbles as the starting point for the simulation. It was then clear that the larger bubbles always acted too quickly and shot out of the surface. I went back to the source, zeroed each value and slowly worked my way forward. So I got much smaller values for B2B, Variation Large and Rising Speed. In this sense, I have learned from my mistakes and thank you for drawing attention to it.
I am now trying to finish my simulations with this new knowledge. Happy new year to you guys.

[Svetlin.Nikolov]

Awesome, thank you for sharing! Maybe it would be good thar we set up a workflow here and record a video with the recommended steps when doing this kind of effect... And wish you a great new year as well!

[Guest]

Hello everybody
I enjoyed a little bit my free Time. Yes i will record a Video or make a Tutorial about that. Does anybody know a Software which i can use to record a Video of my 3ds Max Screen?
Kind Regards David

[Svetlin.Nikolov]

Oh, this will be even better!

I am often using OBS, it's very much out of the box, after many years of recording with all kinds of fishy software, this one is actually great!