[ PhoenixFD beta2 ] Some issue with liquid and Foam

[ghiom3d]

hello,

I'm trying to full of beer a glasses .
Phoenix looks very easy to setup to do this job. But it was'nt since i can't find why i can't solves my issues after 20H of searching .
Can you help me ?

First question :
When i fill with big cells for preview, my glasses is full, that's ok.
But when i use smaller cells, my glasses is near to empty . How to having the same level of liquid in preview and high quality( big cells and fine ones) ?

Second question :
If i whant to fill a glass without to compute very small cells, i need to use wetting options. but it's staying many stranginess between the liquid and glass. have you an option to solve this intead of growing the number of cells ?

Third qestion :
I want my foam finish on the top of the liquid faster . wich parameter i need to pley with to make the foam trying to go up faster ?

BUG ? :
why my liquid goes down when he must staying ?

Question :
How to make the foam material looks more than beer , less than foam shampoo ?




My parameters are based on the beer sample and looks like that :



thanks to help me , a lot of new options and feature deserve good doc to beeing learn. Phoenix2 looks very very great !

[Ivaylo Katev]

hi,

When i fill with big cells for preview, my glasses is full, that's ok.
But when i use smaller cells, my glasses is near to empty .

by default phoenix uses automatic spf (steps per frame) mode, that means the simulation step is determined automatically giving in account the resolution, the dynamics etc. however, the experiment shows that the automatic spf control is not suitable when our target is settled liquid and because of this in the beer sample manual spf mode is used. however, when the spf mode is manual, the simulation result will be not the same when the resolution is changed. you need to introduce correction in the spf. in general - if you double the linear resolution of the grid (this means the cell size , NOT the count ), you need to double the spf upper limit value.

If i whant to fill a glass without to compute very small cells, i need to use wetting options. but it's staying many stranginess between the liquid and glass. have you an option to solve this intead of growing the number of cells ?

to solve this problem you need to use the gizmo option (see the rendering dialog). currently the gizmo can't use the original glass geometry, you need to prepare a copy and to push it a bit to ensure small overlap of the glass and the water. however, this is very inconvenient and was fised, in the next update (next week) you will be able directly to pick the gizmo and forget for any adjustment.

I want my foam finish on the top of the liquid faster . wich parameter i need to pley with to make the foam trying to go up faster ?

the rising rate. i suppose here you are near to discover one of the most annoying issues of the beer simulation - the remaining circular movement. you will find that even when the liquid surface looks settled and stable, the internal content circulates slowly. just keep the wetting on and set some animated viscosity after the pour is finished to remove the movement.

why my liquid goes down when he must staying ?

the reason is that the classic advection violates the conservation laws. to compensate this the parameter "surface balance" is intended. in the beer sample it is negative, because if is zero the level grows.

How to make the foam material looks more than beer , less than foam shampoo ?

the answer is not good - the beer has too many small bubbles. i suppose for good looking beer you need more than 2M bubbles. this will take significant simulation time, perhaps more than a day. i would suggest to try some fake techniques, i mean to use the fog option. there is an option "as fog if below" that converts the bubbles into fog and shades using the smoke/fire phoenix shader. be careful with the fog resolution, you can overload the memory very easy, because there are no info for the needed RAM yet. currently you can obtain approximated expectations using a test phoenix simulator with the same cell size as the desired fog resolution, it's the same value, just the name is different.

[ghiom3d]

Many thanks for all your understandable answer !

I've seen the remaining circular movement issue that make foam moving again and again inside the liquid. I can understand now why you advice to adjust the viscosity when the liquid seems stable.
Thanks for the Gizmo tips, it's seems to work .

About the Foam wich looks like Foam Shampoo , is it possible to add inside the foam paramaters some options like opacity , bump .. with less opacity and some bubble bumps, i think it's possible to have someting wich looks more dense not ?

[Ivaylo Katev]

About the Foam wich looks like Foam Shampoo , is it possible to add inside the foam paramaters some options like opacity , bump .. with less opacity and some bubble bumps, i think it's possible to have someting wich looks more dense not ?

it will be slower than direct shading of multiple bubbles. perhaps the most realistic perspective is to add bubble count multiplier. wit such a multiplier the foam can be simulated coarse, with 2000-10000 bubbles, just to obtain the general form, and then around every bubble new bubbles will be added randomly only for the shading.

[ghiom3d]

it will be slower than direct shading of multiple bubbles. perhaps the most realistic perspective is to add bubble count multiplier. wit such a multiplier the foam can be simulated coarse, with 2000-10000 bubbles, just to obtain the general form, and then around every bubble new bubbles will be added randomly only for the shading.

yes it's could be nice to add a count multiplier on shading .

[ghiom3d]

when i use Gizmo , my Yellow liquid appear full transparent and uncolored !
when i switch off the Gizmo, it's appear fine yellow.

What i'm doing wrong ?

[Ivaylo Katev]

nothing, this is a bug that is already fixed.

[ghiom3d]

Wow !! i'm happy to know .

Thanks for your time .. chaosgroup forum is the top of the top !!

[ghiom3d]

this one look better now.
maybe it's fill a little to fast .

[Da_elf]

a little too fast but i like how the foam come over the side. cant wait to see it rendered

[ghiom3d]

Thanks you .
I'm working to find the best parameters for simulation AND rendering this beer .
I like too the foam wich go down and try to find something more natural .

at this time it's more like if i had piss in shampoo