Liquid particles number constantly decreasing

[Oleg_Budeanu]

Hi everyone
I am trying to simulate simple one jet fountain with a pool underneath.
I've managed to set "initial fill", made the shape of the pool - everything's ok here, everything outside the pool is being deleted.
One cylinder polygon is emitting particles with high velocity and it looks great.
Now the problem is that at about 550 frames of simulation the liquid particles start to just disappear.
I am simulating from -150 to 480 frames.
The look goes from this https://drive.google.com/uc?id=1LcxG...jNPvm-uXCz2H-F
to this https://drive.google.com/uc?id=1QB1a...7d9rbpC9Wfnsw-

This is how it looks like in 3dsmax : https://drive.google.com/uc?id=1kc1l...9f1_BHnzSjXAVq
In the end the pool is almost gone : https://drive.google.com/uc?id=1PV3X...5XgKkXISvLOYMi

There is no leak or something like that - particles are just disappearing, you can see the amount in the phoenix preview going down.
Can you please let me know what the issue can be?
This is the file : https://drive.google.com/file/d/1XmQ...ew?usp=sharing
This is the early version, later on I tried to increase the grid density (decreased cell size), I also increased substeps - nothing helps.
Some help will be much appreciated.
Thanks

[Oleg_Budeanu]

I've sent this to support as well, because I've spent 2 days to find a solution but did not succeed. Please , check it out, ticket number 139735

[vladimir_krastev]

Hi, thanks for posting. I will check the scene and get back to you.

[Oleg_Budeanu]

Hi, thanks for posting. I will check the scene and get back to you.

Hi Vladimir
Thanks. Is there any update?

[vladimir_krastev]

Hi, thanks for contacting us.
The particle tuner that you are using is deleting your initial fill up particles as well as the ones from your source.
I suggest you change you setup a little. Disable the initial fill up from your Grid. Instead use the inner walls of the fountain to create a fill up geometry. Right click on it and choose phoenix properties and then enable the "initial liquid fill" check box.

This way only the selected geometry will be filled up with liquid when you start the simulation.
After that you can use the particle tuner but change the condition. Use "age" instead of "distance" or you can create a second liquid source but set the outgoing velocity to negative value and this will delete particles that come in contact with it and act as a outgoing tube of the fountain.

[Oleg_Budeanu]

Hi, thanks for contacting us.
The particle tuner that you are using is deleting your initial fill up particles as well as the ones from your source.
I suggest you change you setup a little. Disable the initial fill up from your Grid. Instead use the inner walls of the fountain to create a fill up geometry. Right click on it and choose phoenix properties and then enable the "initial liquid fill" check box.

This way only the selected geometry will be filled up with liquid when you start the simulation.
After that you can use the particle tuner but change the condition. Use "age" instead of "distance" or you can create a second liquid source but set the outgoing velocity to negative value and this will delete particles that come in contact with it and act as a outgoing tube of the fountain.

Hi Vladimir,
Thanks for investigating this and for a solution.
Can you please tell me why the tuner is deleting particles? Is it because of the distance? I've followed numerous tutorials which are using the tuner as it's the simplest option. Can you please explain why it is not a correct option?
Thanks.

[vladimir_krastev]

The particle tuner in your scene is placed between the grid boundaries and deletes not only the particles coming from your source but also the initial fill particles. That is why your fountain is slowly disappearing. The tuner could still be used but you need to change the expression. It is now using the distance to your dummy object to determine which particles to delete. If you set the expression to use "age" instead then you will keep the particles emitting from your source, keep the initial fill particles and prevent the fountain from overfilling.

[Oleg_Budeanu]

The particle tuner in your scene is placed between the grid boundaries and deletes not only the particles coming from your source but also the initial fill particles. That is why your fountain is slowly disappearing. The tuner could still be used but you need to change the expression. It is now using the distance to your dummy object to determine which particles to delete. If you set the expression to use "age" instead then you will keep the particles emitting from your source, keep the initial fill particles and prevent the fountain from overfilling.

Thanks, Vladimir, I will try it out.

[Oleg_Budeanu]

The particle tuner in your scene is placed between the grid boundaries and deletes not only the particles coming from your source but also the initial fill particles. That is why your fountain is slowly disappearing. The tuner could still be used but you need to change the expression. It is now using the distance to your dummy object to determine which particles to delete. If you set the expression to use "age" instead then you will keep the particles emitting from your source, keep the initial fill particles and prevent the fountain from overfilling.

Vladimir, I've checked the documentation, and I am unsure that changing the condition to "age" will solve the problem.
I am unsure if you checked the scene, but my pool is not rectangular, so I have to delete particles outside that shape boundaries. That's why it is set to distance. Also, if you check the scene, you will notice that the volume that is responsible for the particle "delete" condition is much lower than the "fill up" volume. Also, if your statement is correct - the particles would not die from the centre where they are falling from the emitter, but on the whole plane, rather than particles in the centre.
So my question is still there - why are particles disappearing using distance conditions in my case?

[vladimir_krastev]

Hi, the particle tuner slowly deletes the initial fill as the simulation progresses.
Please take a look at the gif below - captured from your scene with disabled emitter. We have only initial fill and a particle tuner.

[Oleg_Budeanu]

Hi, the particle tuner slowly deletes the initial fill as the simulation progresses.
Please take a look at the gif below - captured from your scene with disabled emitter. We have only initial fill and a particle tuner.

Hi Vladimir. Thanks, I understand that. I've tried setup you proposed and it is still behaving very weird :

1 is the negative volume - you can see the particles perfectly travelling in it.
2. in the bottom - is the initial fill volume - it is filled as expected
3 is the liquid source for the negative volume
4 you can see again those spots without particles and particle amount being decreased constantly.

Vladimir, to save time - can you please create a simple setup with an "irregular" pool shape? Just as it is in my scene. I have been struggling with this for a week already. This is the simplest case scenario for any simulation and for some reason, it is so complicated to create!
Thank you

[vladimir_krastev]

Hi, you could actually just use the Initial Liquid Fill and leave it overflowing with the grid set to open Z axis. It depends what is your real life model. Could you share that as well?
Below is the scene with Initial Liquid Fill.

[Oleg_Budeanu]

Hi, you could actually just use the Initial Liquid Fill and leave it overflowing with the grid set to open Z axis. It depends what is your real life model. Could you share that as well?
Below is the scene with Initial Liquid Fill.

Hi Vladimir,
Thank you, I will check the scene and see what's different from my setup.
Well, the scene I sent is actually the "save selected" from the scene. So it is exactly as you see it there. One-jet fountain in the middle of the kind of rhombic shape of the pool.
I will double the link for the max file, just in case : https://drive.google.com/file/d/1XmQ...ew?usp=sharing it's 2023 max file.

[vladimir_krastev]

Yes I meant that a real life fountain will drain somewhere, either from a pipe or from some sort of linear drain across the edge.

[Svetlin.Nikolov]

Hey folks,

I am dropping in on this issue as well.

Please notice that the bottom of the fountain is OUTSIDE of the simulation grid: