Hello,

I have a system of two different particles interacting in a container, I want them to interact until they reach an equilibrium based on their charges and the area of the container, any idea how I should set the charges to create this scenario?

Thanks!

Can you be a bit more specific? Are you taking about two individual particles, or two particle systems? Inside of a container, in sops/pops or are you referring to the dops container of a particle fluid simulation? Are you using flip or sph at all or pure pops?

What is the expected behaviour when the particles are near each other? Are they supposed to behave like oil and water, or what do you mean by charges?

A rough pops solution might be to have two streams of particles, grouping them based on where they were emitted from and using an interact pop and a drag pop. Interact will push/pull and drag will slow them over time. If the result is too jittery you can pull the resulting points through chops and filter them.

If you are dealing with interacting fluids, a modified version of the SPH object with two configure objects seems like the only way to set different particle properties (density, surface tension,…). I have not yet found a way to have two flip fluids with different parameters interacting with each other.

You mean something like this?

http://vimeo.com/8164185 [vimeo.com]

Complete equilibrium is not possible in that case, I think, because the interact pop only works on pairs of particles, so you often end up with little clumps disconnected from the rest living in their own little happy world, or constant movement. Point clouds dont work well in pops so I'd look into dops. But since you talk about particle charges, I think a bit of custom solver setup would be necessary. As far as I know there are no default solutions for charges.

Apologize for the segue in advance.

Soothsayer
Point clouds dont work well in pops so I'd look into dops.

They work very well if you build your POP networks in DOPs.

Take a look at the attached file. FWIW, I build almost all my Particles in DOPs these days. I hate not having scrubbing and this makes using Point Clouds quite pleasant in the POP context.

The problem with Point Clouds in any other context (SOPs) is that the POP results aren't cached. When you try to query the result as a point cloud, it doesn't work. In DOPs, it's easy to set up a method to do this.

Additionally, since this set-up passes the particles through SOPs, well anything you do to the particle points in SOPs is fair game as it will be fed back to the Geometry data attached to the POP Object and yes, this will be used by the POP rules in the next time step.

I've only scratched the surface with FLIP and SPH sims using this technique but it seems to hold together. Remember they are both particle primitive geometry.

That's great Jeff! I also found recently that dops and pops are a superb combination but I always hesitated, thinking there was some hidden performance penalty.

Seems you give the go-ahead on this!

i have attached the file i was working on, the problem is the particles doesn't stop moving.

@pclaes> i was referring to two different particles systems, in pops. i was hoping to produce an effect where the yellow particles would repel one another equally, while the green one would repel the others at a larger distance, but they will all spread into the nooks and crannies of the container and eventually settle down.

i guess i was referring to the effect radius when i said “charges”? like how a positively charged particle would repel a negatively charged one, but referring to the distance of the attraction/ rejection.

@soothsayer> yes, something like the video, but on a flat plane instead of three dimensional. what is a “custom solver setup”?

thanks all!

EDIT: sorry I left out the file! have attached it now