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?
it’s not the lifespan, can you post the numbers in the info panel of these frames?
i mean, for both the frames, to compare the numbers
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 …
it definitely helps. but i still get the problem. but less of it.
is the baubles decrease in size over time?
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
beer_test.zip (139 KB)
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
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
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
so i have changed to rate like you said and it looks great!
thank you!
here is a link to the preview:
And some more explanations
Perhaps you have noticed that usually the size related units are using the scene units, but the velocity threshold is not using the scene units, it’s in grid units, that’s why changing the cell size changes the foam birth.
apparently it’s a bit unexpected for the users, and one may ask why the velocity threshold is not in scene units that will make it cell size independent. The reason is simple - when you run a sim, you have no idea what the threshold must be. But using the preview ranges you can measure what is the liquid velocity in the area that you want to produce foam, and putting the measured value as threshold you have a good starting point for experimenting
Thank you for that.
now i have issue with he behavior of the liquid.
as i increase the cell size, the liquid is moving much faster, too fast and it looks like it was speed up.
i tried to increase the SPF but it didn’t changed that.
i’ve attached in this link 3 files:
one is with cell size 0.4 and SPF 4.
one is with cell size 0.2 and SPF 4.
one is with cell size 0.2 and SPF 8.
what am i missing here?
i can’t see speed difference in the attached files, in all of them the beer hits the glass bottom in frame 7
true, but the splashing is much faster after the hit. looks like fast forward
