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

Figure 85. Detailed Full-Scale CFD Simulation of Flow Reversal on First Floor South-Buoyancy-Driven Flow 4A similar flow pattern was observed using flow visualization techniques discussed in Chapter 4.For the buoyancy-driven full model case, the air from the ground floor entered the atrium, slowlyrising over the railing and then entered the first floor south zone. The air from the atrium washeated and mixed with the heated air in the first floor south zone and then exited at the ceiling.This corroboration of the field measurements, with the full-scale CFD, reduced-scale CFD andreduced-scale air model validates the reduced-scale air model as a method to model even unusualflow patterns observed in the full-scale building. The simplification of the internal loads as auniformly distributed load is adequate in assessing the airflow patterns within the space.The temperatures measured in the reduced-scale air model, when scaled for full-scale buildings,were validated based on the measured building site data for several summer days. The additionof the atrium fans and thermal mass influenced the resulting internal temperatures in theprototype building, but were of less significance in the reduced-scale air model. Had the thermalmass in the prototype building been better used with night cooling, the reduced-scale air modelstill may prove as valid a methodology, however further research is required. The airflowpatterns within the model were validated by both field measurements and observations, andthrough CFD simulations, though additional field tests would need to be completed under otherconditions.4 G. Tan. CFD Simulations of Houghton Hall, Luton, 2004.159