RealFlow | Cinema 4D can also be used for things like sand piles, gravel, or even as source for grass, stones, and other objects. The core of this feature is the fluid container's "Particle" tab, where you see three parameters:
The settings in this screenshot have been used for the image below.
In order to use these random values you only have to group the objects, meant to be scattered, under the fluid container. Then adjust, e.g. "Rotation Random" and "Scale Random", and RealFlow | Cinema 4D will do the rest. If there is more than one scatter object grouped under the fluid container, the probability for an object to appear is always the same: with two objects, the probability for each object is 50%, with four objects it is 25%, with 10 objects it is 10%, for example.
Scattered stones and rocks (ground collision geometry is invisible here).
Scattered objects can be separated through → object buffers by adding "Compositing" tags. This way each scatter instance can be assigned to an individual layer.