The theory of plumes adapted to model air movement in naturally ventilated buildings

This paper describes ongoing research toward the development of simplified techniques for the prediction of air movement in large, naturally ventilated spaces containing hot and/or cold surfaces. Me situation where two distinct sources of heat are present on the floor of a naturally ventilated room is discussed Thermal stratification develops such that two layers of warm air form above a lower layer at ambient temperature. The heights and temperatures of these layers are predicted using forced plume theory, ie. where a plume is initiated from, a source of buoyancy with finite mass and momentum flux). Interface heights are found to depend on room height, ventilation opening size and on the ratio of the heat fluxes from the two sources. The intensities of the heat sources have no influence on interface heights. A theoretical and experimental investigation of a naturally ventilated enclosure containing both positive and negative sources of buoyancy is also presented. Large glazed spaces such as atria exhibit significant thermal stratification due to radiative heating of internal surfaces. The possibility of extending the plume analysis for isolated sources of buoyancy in a space to that where the sources of buoyancy are distributed is discussed.