Amount of fluid keeps increasing without discharge

[bobweb]

Thanks a lot for all your effort! Unfortunately my result is not the way you described. Yes, it behaves differently, it is right there without settling time and I had to lower the viscosity now to get it even out of the glass. But now I have cells stuck in the wall of the glass and the volume problem persists (see attached previews). Don't get me wrong here, your support is absolutely great (!!), but the hunt for the right combination of system units/SPF/gravity/viscosity is becoming rather tedious, since every value can change everything, and the deadline approaches menacingly.

What would you consider as a high SPF value to get it over with?

And thanks for the hint on the velocity checkbox, I forgot to check that.

[Ivaylo Katev]

well, because your scene produces some UI lag that i can't explain, i decided to make a very fast setup that makes what you need (if i understand correctly), so just replace the geometry with yours.
you can try to retype the settings into your scene, but it's very probably that the reason for the problems will remain.
in the attachment is the scene and a small avi showing the result.
however, you will need the latest nightly build to achieve the same result, because i'm using forward transfer to simulate the upper container, the classic advection is less physically correct but unfortunately is very stable and only with it you can achieve perfect flat liquid surface. in the official build the forward transfer advection produces boiling, this was fixed last month. beside the viscosity i'm using surface tension, it improves the viscosity result, but also requires nightly build.
so, contact the support, and tell them why you need nightly access (or directly paste a link to this thread).

btw, note that i'm using different cascade setup, now the transferring source is in brush mode, seems to work better like this.

[Paul Oblomov]

Surface tension still drags liquid somewhere...

[bobweb]

Thanks for the nightly build access, several simulations later here is an update to my case:

- At first I tried a very high SPF increase to 128. It made things a lot worse, the liquid mass raised so quickly, it shot out of the second container like a small volcano.
- For testing purposes of my machine I rebuilt your scene completely from scratch and it simulated just the same, so at least no installation oddities as it seems.
- I merged my geometry into your scene. My objects came in a lot smaller than yours. I am not sure anymore if this was just a result of fiddling with the system units or they were smaller all the time. Anyway, I made everything bigger to fit your objects.
- I could not use the penetrating fill technique, because of all the cells stuck in the wall and having to render transparent glass, so I made the emitter smaller. This lead to vanishing cells. They did not drop out anywhere, they just disappeared downward, at the time of the rotation it was nothing left to pour out. This was fixed by switching back to classic.
- Then I fiddled around with all the settings to get the viscosity I was after. Some settings basically worked, some don't, some had new strange problems, where the fluid did not stop to pour out from the upper container, like a stuck cell producing new cells all the time - I can't recall them all. Eventually I came up with a sim I could use for the intended shot.
- The only problem left were some visible grid steps along the round glass walls. So I made only the cells smaller, simulated again - and got again a volume increase of about twice the amount of the further simulation and the viscosity got a little more fluid. Frankly, this is driving me crazy. Change one value and you have to start from scratch for all the others, and with more cells to simulate this becomes even more tedious. It is a pity there is no absolute interpretation of a value, e.g. viscosity of 1 can be anything, like very fluid freshly melted chocolate or a slug, all being relative to other values. Therefore I often did not know, which value to change first to get a behaviour in this or that direction.

To deliver on time I surrendered. I got away with highly mesh-smoothed sim keeping the bigger cells, but I am not really satisfied. Whenever there is the next project with fluids, I will have to calculate way more sim and testing time... And maybe you can do some magic to make volume preservance more easy or at least find a solid guideline to work around.

And by the way, why did you block the option in the nightly build to start a simulation via script? This was quite handy to automatically start the sim of the second container, after the first one finished. Now I had to stay in front of the computer and wait for it to not lose sim time. An overnight sim of the whole cascade would not be possible anymore. So please bring this feature back.

Thanks for all your help, maybe you still have some tipps, what could have went wrong, I would still be interested in that!
Bob

[Ivaylo Katev]

The only problem left were some visible grid steps along the round glass walls. So I made only the cells smaller,

and

I could not use the penetrating fill technique, because of all the cells stuck in the wall and having to render transparent glass,

this problem is very common and is described here . the solution is described in the help (use gizmo), just to add that by default the liquids are rendered with the mesh option, that does not support gizmo yet, and you have to replace it with a standard max boolean operator.
the beer sample scene (see in your documents/phoenix fd/samples folder) uses gizmo to render the glass.
i strongly recommend to use FT in your case, beacuse it has no problems with the liquid quantity. can you post simple animation of these vanishing cells that made you to use classic advection?

[bobweb]

Ah, ok, I did not know about the gizmo feature in conjunction with the render mesh option. That helps a lot. It is in the docs, so I should have get it there. Still I would say this feature could be named more like what it does instead of just "gizmo" in the UI and grey out, when render mesh is on. Especially when calling it gizmo, I first thought only atmospheric gizmo objects could be used for that.

I have attached two videos, both using Forward transfer in the upper container, one with a non-penetrating emitter where the quantity just fades away and one with a penetrating emitter, very nice and stable behaviour - but still about three times the volume in the second container.

Thanks,
Bob

[Ivaylo Katev]

well, then make the advection of the lower container FT too, the volume will be stable and because the liquid is viscous will be no problem (hopefully).
the vanishing animation is strange, not sure what causes this

[bobweb]

Oh yes, finally, this works (see attachment), and did not even take a lot of simulation time.

Thanks for all your help,
Bob

[Ivaylo Katev]

congrats!
could you share the final video?