Haven't had much luck trying to create a mask for a gas dissipate node in a pyro solver. The mask I have set up currently works with the gas turbulence node according to the documentation:

https://www.sidefx.com/docs/houdini/pyro/pyro_look.html [www.sidefx.com]

However it isn't immediately clear how to use this to mask a gas dissipate effect. The goal is to ‘feather’ the top of a smoke sim. It's not something I think would happen in real life, which is probably why I'm struggling.

Picture attached - the increased turbulence at the top would idealy be more diffused after using this node. Any ideas? Might need to do multi solver and a seperate sim. Or something else entirely.

6-months-later follow up on this, maybe it'll help someone down the line. It's really pretty straightforward.

The pyro look development page suggests to attach it to the density binding on the node, which works for turbulence but it more generically works when the custom-made scalar field is entered into the ‘control field’ of the dissipate/turbulence/disturb nodes and so on. If you dial up the control influence to 1, it should just work if the values in your scalar field are correct.