Multiple sources of buoyancy in a naturally ventilated enclosure

Abstract

This paper presents an approximate model of the flow and stratification within a naturally ventilated enclosure containing multiple sources of buoyancy. The sources are assumed to produce plumes which rise without interaction throughout the enclosure. Buoyant fluid accumulates at the top of the enclosure and flows out through upper level openings, and ambient air flows in at low levels to generate an upward displacement ventilation. It is shown that the sources produce a multiple layered stratification with each plume terminating in a given layer. The weakest plume, with the lowest buoyancy flux, produces the lowest interface, and stronger plumes rise higher up within the space before discharging their buoyant fluid into the environment. The model is approximate in that it ignores the stratification within the space when calculating the properties of each plume, and it is shown that this approximation is satisfactory over a wide range of conditions. As a result it is possible to calculate the stratification and ventilation rate for any number of unequal, and equal, sources of buoyancy within a space.