water slow down

[mumle]

Hi,
I have a scene where I need to go from normal speed to slow motion (because its water). I have tried changing the play speed, but when I do that, the water will pulse, no matter which grid blend I use.

Is there a way to fix this with resim, so I only have to work with what I want too and not the whole sim?

[mumle]

I am on version 4.4ish

[Svetlin.Nikolov]

Hey, it is possible that the liquid will pulsate in case there is liquid being born from a source - can you show how the setup looks? This will behave better if you have the Particle ID, Particle Age and Particle Velocity exported in the original simulation from the Output rollout - can you check if you have all of these?

[mumle]

ID and age is was enabled. I test it at 0.1 playspeed

[mumle]

ID was also enabled

[georgi.zhekov]

Hey,

Thanks a lot for the scene. In your case you have a very fast emitting liquid and slowing it down through the Input rollout won't work very well.
What you can do instead is to use the Time Scale option in the Dynamics rollout. You can find more about it here - https://docs.chaos.com/display/PHX4MAX/Liquid+Dynamics

So for your scene if you wish to make the liquid move slower only at a certain point in time you can animate the Time Scale. You can also animate the steps per frame accordingly, so if you use 16 steps per frame for the normal movement and you animate the time scale to 0.1 for example, you can animate the steps to 1 or 2.

Hope this helps!

[mumle]

Hey,
I am trying to do that right now. But when I do my timeramp the water just goes bonkers and behave erratic. Even if I leave the stepsize as the same.

[georgi.zhekov]

Seems to be working correctly here with your scene. Can you show us how it looks on your end and how you animated it?

[mumle]

Is there a mail where I can send directly to you? Client stuff and such.

[georgi.zhekov]

You can use the submit a request form link at the top right corner here - https://support.chaos.com/hc/en-us

Thanks!

[mumle]

I have submittet the file and a few examples of the sim-files.

[georgi.zhekov]

Thanks for the files, looks like it is not the slowing down that makes the liquid to move this way as it is scrambled even when it is fast at the start.

I would suggest adding a bit more surface tension and possibly a little bit of viscosity as the steps per frame are already high. You can also try to make the grid smaller at the start and use the adaptive grid to expand it over time - this should help with the simulation time.

[mumle]

The more surface tension and viscosity I add , wont I move it more away from how water looks and behave?

[georgi.zhekov]

Yes, but adding just a little should help. The other option would be to add more steps and grid resolution but this will make the sim slower so you will have to balance between these.

[mumle]

I've tried turning up for both, also alot, just to see what happend, still getting the same reaction. Now trying turning the steps up to 20