Simulation bugs (low fps, missing objects)

[674716977]

When I was running the Fluid demo (simulation->Demo Scenes->particles->Fluid Isosurface), something went wrong. First of all, this fps is only 8fps, and when run to a certain point, fluid objects are lost.
Here are the symptoms of the problem:
At the beginning

In operation

As you can see, fps is low and objects are lost.The running environment is isaac sim 4.0. My system is ubuntu22.04 and GPU is 4090, as shown below:

But when I run this demo on a device with the 3070ti, I don‘t have these issues.
This is my run log：
kit_20240907_122848.log (978.3 KB)

[674716977]

Now I think it’s isaac sim 4.0 because I had this problem when I ran this demo on the previous 3070ti.

[twidmer]

Hi, it’s a fact that this demo scene is very slow, not even close to real time. Unfortunately that’s not going to change soon since fluids are not a priority anymore since they are not essential for robotics simulation, at least not now.
About the problem of the fluid disappearing: The isosurface is built on a sparse grid and once that runs out of blocks, the surface disappears. It runs out of blocks due to the leaking of fluid through the side walls (leading to the fluid particles all over the place) which happens when the simulation frequency is too low. It’s set to 60, changing it to 120 should solve the issue to a large degree. The scene used to work with 60 sim steps per second, I created a ticket to investigate the issue. You can also disable the isosurface on the particle system node by unchecking the checkbox labelled “Isosurface Enabled”. Then you see the particles which don’t disappear since they don’t rely on a grid for rendering.
Hope that helps and thanks for reporting the issue.