Here is another simulation with more options.
ga,gb,gc to adjust gravity for different particles.
gscale: adjust over all gravity scale
vscale: adjust over all velocity (to change ratio between relative thermal energy and gravitation energy )
diameter: to change the collision rate.
I can not find the right parameters to show what you would like to see.
May be some other factors need to be considered.
It seems that you are trying to using particle model to simulate fluid behavior.
I think we need to find a better model to simulate what you want!
I will be busy for a few days.