Investigation into two-sided windcatchers used for room ventilation

University of Technology Sydney. Faculty of Engineering and Information Technology.A windcatcher is a structure for ventilation purposes fitted on the roof of a building to induce the stale inside air to the outdoors and supply the fresh outside air into the building. The experimental studies of windcatcher systems for all cases are obviously costly or even impossible in practice. The assessment of the performance of windcatcher systems using Computational Fluid Dynamics (CFD) is very important for both their designs and improvements; CFD has become a reliable tool for flow analysis in buildings. This thesis investigates the effects of some key factors on the performance of a two-sided windcatcher fitted on the roof of a typical room. A CFD software package developed by the ESI group is used for the quantitative and qualitative analysis of velocity magnitude, flow patterns, and ventilation flowrate. For all cases, RANS (Reynolds Averaged Navier-Stokes) CFD technique with the standard two-equation K-εturbulence model is employed in steady state conditions for incompressible turbulent air flows. Based on the simulations and analysis, a model is selected. A LES (Large Eddy Simulation) CFD technique employing the Smagorinsky subgrid-scale (SGS) turbulence modelis used for evaluating the selected model in transient conditions. Results from RANS and LES are compared; and they show good agreement. To verify the computational results, a laboratory scaled model from the selected computational model is constructed and these are compared with the experimental measurements; and fair agreement has been obtained. All these investigations would lead to a significant development in evaluation and performance of two-sided windcatcher systems. This work has resulted in 8 research publications which are listed in Publications Section