@danmoreno i tried it out, it works okay. to make life painful i did it in one dop and using sparse. i recommend 2 dops for simplicity
find_densitymask on the left looks for the intersection of the rising smoke and the sphere and handles the dissipation inside the sphere. transfer_density on the right side reaches into the other dop object and uses the densitymask as an emission source. because it has collisions on, the smoke stays inside.
warning: this one-dop-sparse setup has all sorts of dumb shit to keep the second solver active and tracking the other one
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http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20204005/18/20/smokefill.mp4
http://fx-td.com/houdiniandchill/wp-content/uploads/discord/20204005/18/20/smokeFill.hiplc