Numerical investigation of wake-induced non-steady ventilation flows

Ventilation of buildings by passive buoyancy and wind driven mechanisms is often exploited to maximize the displacement of contaminants so that good levels of indoor air quality and thermal comfort can be maintained at a minimal energy cost. Classical quasi-steady fluid dynamics approaches are commonly used to estimate wind driven bulk flow rates and ignore the effects of unsteady phenomena. In geometrically complex urban settings wind conditions impinging on building facades are dominated by large wake structures induced by adjacent upstream buildings. The large size of these vortex structures in relation to typical window size means that they can be powerful drivers of rhythmic variations in ventilation flows – sometimes resulting in complex pulsations of air movement in and out of adjacent or opposing windows that enhance overall ventilation rates. This project would seek to carry out numerical investigations of such wake-induced unsteady ventilation phenomena using Large Eddy Simulation approaches. The project work would make use of existing experimental data sets to develop appropriate numerical methodologies. A series of prototypical simplified building and window geometries would be investigated to evaluate the net effect of large scale fluctuations in the flow when exposed to different upstream vortex street conditions.