Modeling a pile of dry sand: Angle of Repose - FleX

Hello, I’ve recently been playing around with the demo that comes coupled with the FleX repo in order to simulate dry sand particles.

Something I have noticed is that even though I set the the friction properties as needed, the “sand” particles keep spreading out slowly and never achieve the expected angle of repose.

According to: https://en.wikipedia.org/wiki/Angle_of_repose the angle is based only on the static friction coefficient.

I have set values in the range of 10-400 for staticFriction, dynamicFriction and particleFriction but they particles still spread out slowly and never seem to come to a rest.

I am still fairly new to FleX and was wondering if anyone can give some insight as to why this might be happening and possible steps moving forward.

A temporary solution was to set the sleepThreshold param to fix the particles when they are moving slow.