Adding temperature to an explosion post-sim (example given)

[zbugni]

At 13:52, this video briefly glosses over using simple geometry to add temperature to a specific area of an explosion:

This is pretty much exactly what I want to achieve.

The setup looks simple enough, except for an attribute wrangle where he doesn't show what's happening. Does anyone have any idea how he might be doing this? (Any other methods are welcome too!)

[dleonhardt]

I'm assuming that he used the volumesample VEX function inside that Wrangle to get the distance from the surface of that Torus VDB, then remapping those values to a 0-1 range so he can use them in a ramp.

dl_post_sim_temp.hipnc