Gas diffusion through halls

[Threehorns]

I noticed a CO2 pile up in the right most lower corner of my dormitory, just below a vent of fresh oxygen.
the pile up ended up locally well over 3kg per m³ of CO2 (over a couple of squares), while i was pumping around 300g pure oxygen through the vents.
 

solution i used was to just dig a drain tunnel for the CO2 with an inlet grate at the proper spot. Watching the resulting effect was almost like looking at the gasses of a cannon firing, in slow motion.
So there definitely was some motion, and considering the drain tunnel ran right to left, I assume the vent output somehow created a curtain of air that trapped the CO2.

No suggestions made, only an observation with a game-build solution.
But maybe creating airflow based on volume density. And allow volume density to naturally equalize.
So, its not just air that randomly move, but
- it can gain part of a volume if lower pressure or
- donate if higher pressure or
- even divide into a new bubble, forcing two other bubbles to merge.
- and than recompute from step 1.

Otherwise ... to quote Will Smith in Hancock ... Good Job! ...