Foam is dying?

[omere]

Hello,
i've continued to play with the beer sample scene.
right now i'm getting nice foam but it doesn't stay. it looks like the particles are dying. but i have tried to increase the life span from 10,000 to 100,000 but it didn't change anything.
is there another parameter that i need to change?

[Ivaylo Katev]

it's not the lifespan, can you post the numbers in the info panel of these frames?

[omere]

sure

[Ivaylo Katev]

i mean, for both the frames, to compare the numbers

[omere]

oh ok.
here i
t is

[Ivaylo Katev]

the count of the second frame is bigger, i think just the bubble size is too small
try to increase it slowly, for example 0.15, 0.2, 0.3 ....

[omere]

it definitely helps. but i still get the problem. but less of it.
is the baubles decrease in size over time?

[omere]

i've noticed now that if i take the distribution value to 1.0 i manage to keep the volume better.
but i guess that i will not get a good size pattern during render.

[omere]

the foam is still retreating from right to left for some reason. even with higher B2B and with higher foam count and bigger bubbles.
it looks like the bubbles are dying from left to right

[Ivaylo Katev]

the bigger b2b does the opposite, it makes the foam "harder", perhaps you have to use lower value.

is the baubles decrease in size over time?

of course not, better see the attached scene, it's the beer sample reworked for flip solver

[omere]

actually this is the scene that i have started with.
but i was trying to increase the quality.
those are the changes:
cell size - 2.0
steps per frame - 14
time scale - 0.5 --------- so the liquid will pure in a regular speed.
vel.threshold - 95 --------- to get more foam
bubble size - 0.15
distribution - 2000
b2b - 50 ------------- in order to get a foam which is closer to beer foam in its consistency.
surface lock - 1.0 ------------ hoping that it will lock the foam to the liquid surface

[Ivaylo Katev]

well, i will try to describe a general way how to change the settings keeping the general behavior
cell size - you decide the new one, but the change factor is very important, it will be used in the rest of the settings. let call the old/new ratio k, i will use this below
steps per frame - increase by k
time scale - do not change, use the source parameters instead
vel. threshold - increase by k to keep the behavior, but to get more foam you have to use the birth rate, not the threshold
bubble size - it depends on the desired look of the foam, but is highly connected with the bubble count and the foam volume. if you want to decrease the size twice, you have to increase the bubble count (the birth rate) eight times to keep the same volume.

[ghiom3d]

well, i will try to describe a general way how to change the settings keeping the general behavior
cell size - you decide the new one, but the change factor is very important, it will be used in the rest of the settings. let call the old/new ratio k, i will use this below
steps per frame - increase by k
time scale - do not change, use the source parameters instead
vel. threshold - increase by k to keep the behavior, but to get more foam you have to use the birth rate, not the threshold
bubble size - it depends on the desired look of the foam, but is highly connected with the bubble count and the foam volume. if you want to decrease the size twice, you have to increase the bubble count (the birth rate) eight times to keep the same volume.

Very interesting !! thanks you

[omere]

but then changing from cell size of 0.45 to 0.2 means: 0.45/0.2 = 2.25
vel. threshold increased by k will be 100*2.25 = 225.
isn't that too high threshold? no foam is being created now

[omere]

so i have changed to rate like you said and it looks great!
thank you!

here is a link to the preview:
https://we.tl/grX9XvhqTK