+- Obi Official Forum (https://obi.virtualmethodstudio.com/forum)
+-- Forum: Obi Users Category (https://obi.virtualmethodstudio.com/forum/forum-1.html)
+--- Forum: Obi Fluid (https://obi.virtualmethodstudio.com/forum/forum-3.html)
+--- Thread: Help Particles stuck together (/thread-2735.html)
Particles stuck together - Samadhi - 03-02-2021
Hello, I have another new question.
There are times in which some particles get "stuck" together and start to "spin" endlessly. As seen in the attached video.
My question is why is this happening and how can I avoid it?
RE: Particles stuck together - josemendez - 04-02-2021
This is completely normal and happens due to surface tension. Pressure acts to separate particles, surface tension acts to keep them together. 3 particles is the minimum stable structure that can be formed, akin to a small drop in the real world. Anisotropy gives them that star-like shape, with minimum anisotropy (1) in the solver (see: http://obi.virtualmethodstudio.com/tutorials/obisolver.html) you'd see 3 round particles in the corners of a triangle.
They spin endlessly because there's little or no numerical damping with so few particles involved, so once they gain energy (for instance when 2 particles attract the third one) they never lose it.
You can either reduce surface tension in the fluid blueprint if you don't want clumps of particles to form (will affect the entire fluid) or apply some velocity damping in the solver if it's the spinning that bugs you (again, this will affect the entire fluid).
cheers,