how to Flow in PhysX

[oneanime]

I am trying to simulate fluids using PhysX and accelerate the process on the GPU. However, I couldn't find any examples or demos in the flow folder.

[vreutskyy]

Hi @oneanime,

PhysX and Flow are separate libraries, although they share the same repository. Flow is not actually part of PhysX.

You can find Flow's documentation here: NVIDIA Flow Documentation.

On the other hand, PhysX has its own method for simulating particle-based fluids. For examples, you can check out SnippetPBF and other related snippets in the PhysX SDK. You can find the documentation for PhysX's particle systems here: PhysX Particle Systems Documentation.

[oneanime]

And
Thank you for the amazing project! I'm currently studying physics-based simulations and I wanted to ask if the fluid simulation in this project is based on the SPH (Smoothed Particle Hydrodynamics) algorithm? If not, could you briefly explain which method is used for the fluid simulation?

[vreutskyy]

Hi @oneanime,

Thank you for your interest in the project! The fluid simulation in PhysX is not based on the traditional SPH (Smoothed Particle Hydrodynamics) algorithm. Instead, it uses a more advanced method called Position Based Fluids (PBF).

PBF was introduced in this paper: Position Based Fluids by Macklin and Müller.

Here are some key points about the fluid simulation in PhysX:

1. It's based on Position Based Dynamics (PBD), with PBF being an extension specifically designed for fluid simulation.

2. PBF improves upon SPH in several ways:

   • It's more stable, allowing for larger time steps
   • It better preserves fluid volume
   • It handles surface tension more effectively

3. The main difference is that PBF solves for particle positions directly, rather than computing forces and then integrating to get positions. This approach makes it more stable and easier to constrain.

4. PhysX's implementation also includes further optimizations beyond the basic PBF algorithm to improve performance and visual quality.

If you're studying physics-based simulations, I'd recommend reading the paper I linked above. It provides a great introduction to the PBF method and its advantages over traditional SPH.