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Numerical analyses based on CFD steady RANS were conducted to investigate the effects of roof configuration on wind-induced natural ventilation for an isolated roofed building. Gable roof and saltbox roof building models were tested with 15˚, 25˚, 35˚ and 45˚ roof pitch in present study. The flow field information and flow characteristics were obtained from the contours and plots generated by CFD. In accordance to the increment of roof pitch, the turbulence kinetic energy and mean velocity ratio show vigorous response. The flow separated at the windward corner do not reattach onto the roof, thus induced higher velocity gradient and form a large vortex at the roof ridge. The vortices behind then building caused by the flow separation at the roof ridge extend along the mixing layer and spread up to the roof. The pressure differences mainly rely on the roof shapes. Greater pressure differences between the upstream, interior and downstream was observed in saltbox roof cases. This is due to the extended roof height which boosted the impinging effect caused by the incoming wind. Generally, the saltbox roof configuration exhibit better performance than gable roof in terms of the measured parameters.

This study investigates the effect of opening position on the indoor airflow of a natural ventilated isolated building model. Furthermore, the opening configuration which generate the highest ventilation is to be determined. Seven different opening configurations were considered by varying the opening position on the windward and leeward walls which include three cases of aligned openings and four non-aligned openings. Models with different opening position were simulated using Computational Fluid Dynamics (CFD) with 3D RANS turbulence model Shear Stress Transport (SST) k- ω. Simulation result indicates the indoor air velocity as well as pressure distribution highly depends on both inlet and outlet opening positioning. Different opening configuration influences the recirculation zone generated within the building model. Comparison shows openings located near the roof generate 6.52% higher ventilation rate compared to openings located near the ground. The study concludes that opening position holds a crucial role in affecting internal airflow pattern, air recirculation and ventilation rate for a natural cross ventilated building.

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