Hi all,

I have this grain simulation going which is showing very unrealistic breakup patterns( see attached images.)
The grains are initailly sleeping and are awoken by the proximity of the butterfly via a POP awaken. The clumping of the grain has been mapped with a turbulence noise. Both work and look great at lower sim resolutions. Dialing up the Sim resolution results in this artificial looking rectangluar splits in the body, which are certainly not lining up with the mapped turbulence.
Any idea on how to get rid of this?
It's especially frustrating since the Sim at high resolution takes along time and the problem does not show up or is more likely just not noticeable at lower resolutions.
Kind regards,

Ben

I once encountered what I think must be the same issue. IIRC I narrowed it down to the way the constraints propagate throughout the model and/or how the grains are stacked. Unfortunately I don't remember the specifics or if I found an easy fix. Would like to know too.

Try to increase the constraints on the grain solver. The constraints works like how much layer can stacked one over another. So if you have 20 constraints, the solver can stack 20 particllayer. I am not sure if its 100% right…
But if you increase the resolution, you have much more „stacked layer“ to solve in stable way. so you have to increase the constraints much higher which cost a lot of simtime.

So my approach is to use low particle count as possible. Then I would upres the sim with point replicate SOP or you could use the vel field from the grainsim to drive some dumb particles(high count).

I found that not using “Self Awaken (awaken by nearby particles)” solves this issue. It might still be related to the contraints number though.
I had it set to the default of 10. Just like you suggested I had used the particle replicate in my above examples already, the initial point number even before duplicating was already high though, around 27Million points.

Here is a screengrab of the sim without Self awaken.:

comming out quite nicely. I like how the face coming down. Now I want to see the animation