reliable(r) collision objects in FLIP

The deforming object shelf button serves most collision purposes, even for static objects (turn off use deforming objects) but sometimes it doesn't quite cut it.

Add a trail node, set to "calculate velocity" to your moving geometry.
Create a VDB from polygons node, setting the name of the volume to "collision" and add a point attribute at the bottom, choosing the "v" as the option. Name this "collisionvel". These names are defaults in Houdini.

In your FLIP sim dop-network, add a "volume source". Set the initialisation to "collision" and navigate the SOP path to the VDB you made earlier. Set the scale to -1, because that's how the maths work..and change the velocity to whatever you want..1 is probably sensible.
Finally plug the volume source into the "volume" connection tab of the Flip solver.

That should be it.