Loading Minerals into container?

Hi Folks

Looking for some ideas on loading (simulating ) coal, gravel etc into an open bodied actor (eg Railway wagon).

The way it has usually been done is when loading is triggered a shower of short life particles parly obscures mesh(s) that rise up the wagon body.
I am looking for something a little different as with that method you always finish up with the same load profile.

Can particles have an infinite life ?
Can they be constrained by geometry (movable)?

I am thinking along the lines of
Intial small particle stream, that changes to very large infinite life particles that represent the finished load profile.

I am sure that there will be better ways can particles deform a mesh ?

All avenues open, looking for some off the wall ideas

Cheers

Sly

Railway Progress