Methodology for the Evaluation of Natural Ventilation in ... - Cham

uoyancy case the air from the ground floor rose in the atrium and ‗fell‘ over the solid railinginto the heated zone of the first floor zone above. This also occurred between the first andsecond floors on the north side of the model, the physical reduced-scale air model, reduced-scaleCFD model and full-scale CFD simulation. Having the railings in the models allowed cooler airto collect at the base of the railing near the column in the pure buoyancy-driven case, whereas inthe case without railings, the cooler air mixed with the warmer air in the atrium. Figure 84shows the temperature distribution with and without railings for the reduced-scale CFDsimulations.Figure 84. Influence of Railings on Temperature Distribution for Reduced-Scale CFDSimulation; a) without railings, b) with railings.Field measurements from the prototype building provided unusual airflow patterns on a day withrelatively low ambient wind velocity. At the first floor south zone, a flow reversal was observedusing the smoke pencils for airflow visualization. A full-scale CFD simulation was completedby G. Tan, for the specific space within the building, and included details such as desks,computers and individual people, rather than a uniform distributed load, as was used in thereduced-scale air model. An image from the simulation, with the curved lines indicating airflowstreamlines predicted by CFD and arrows indicating flow direction from field measurements isshown in Figure 85.158