How to exclude smoke from collision mesh I am trying to achieve an effect where I drive an invisible cone through a simple smoke domain, which clears the smoke from the cone-shaped region. I'm planning to make the cone invisible by disabling "Camera" in its Cycles settings.

The problem I'm having is that even though the cone is a collision object for smoke physics, and although it does indeed disturb the smoke, there is new smoke appearing inside the cone as it advances. I need the inside of the cone to be a smoke-free region.

I've tried Boolean modifiers on the particle emitting plane, and on the smoke domain cube, but to no avail. I still get smoke inside.

Any idea how I can achieve this?
Ah. It looks like I was misled by the viewport. In the viewport, I see smoke inside the cone (I've got the cone set to wire). However, when I render in Cycles, the area where the invisible cone is has no smoke in it. Confusing, but I can live with it... :)