The function of the swirl pot is to use centrifugal force to remove the oil from the air.
The air is then passed through a second chamber (see second step below), and extracted through the top of the AOS. Gravity then sends the remaining oil down the walls of the swirl pot and collects in the bottom of the AOS. At this point the separated oil sitting on the bottom of the AOS is returned to a baffled chamber in the center of the engine block.
The second step involves a second chamber located within the first chamber. As the separated air moves up inside the AOS, it must enter the second chamber before it can vent out the top of the AOS. The function of the secondary chamber is to remove any residual oil that may have made its way up the swirl pot. The secondary chamber also has a drain to return any separated oil back to the engine.