A hybrid displacement mixing ventilation regime in a naturally ventilated room.

The evolution of the temperature profile in a warm room driven by a natural ventilation flow which develops when the room is connected to a cold exterior by two openings at different vertical heights is explored. With the openings at the top and base of the room, we find the classical displacement ventilation regime provides a leading order description of the flow. With openings at the centre and top of the room, the ventilation is hybrid, with the lower part of the room being well-mixed, and the upper part being stratified by an upward displacement ventilation flow. We present some dimensional scaling, two end-member models and a series of analogue experiments of the process. The suite of experiments involve two different configurations of openings and a variety of temperature differences between the interior and exterior temperature.