Forgive me if this is basic, but I'm fairly new to working with Houdini. I'm trying to sim deforming static objects pushing up through a flip tank and can't figure out why particles aren't flowing through the open areas. My Collision Guide looks good so I'm not understanding what I'm missing.

If I switch my mode to “Ray Intersect” the particles act how I'd expect but it slows to a crawl. Should I just stick with Ray Intersect or is there something I'm missing with Volume Sample?

Figured out what I was missing thanks to the Flip Fluids Illume webinar [youtu.be].

Issue resolved by decoupling the Collision Separation on the Flip Object and reducing until my Collision Guide vis looked good.