EFFECTS OF HEATED WALLS ON OUTDOOR AIRFLOW DISTRIBUTION

Abstract

In Singapore, building surfaces experience high amounts of insolation all year round. Due to the heated building surface, buoyancy of air increases, which can affect air flow patterns within a street canyon. In this dissertation, simulations of 2D canyons with aspect ratio of 1 were conducted to study the effects windward walls heated to different temperatures and heights had on airflow patterns within the canyon. Temperature contour plots, velocity contour plots and velocity vector plots were generated for the various canyon heights and temperatures. The higher the Richardson number (Ri), the more buoyant air is. For canyons with the same Ri value, airflow patterns within the canyon were similar with minute differences in velocity, regardless of the height of the canyon. For Ri = 0, there was main vortex in the canyon. For Ri = 0.5, a secondary vortex was formed in the bottom half of the canyon. For Ri = 1.0, the secondary vortex moved towards windward wall. For Ri = 5.0, the main vortex moved towards the leeward wall, and the secondary vortex moved towards the windward wall. Across canyons with the same height, the intensity of the secondary vortex that formed in the canyon increased with increasing Ri value. However, as the use of 2D square canyons in the simulations are not representative of real-world conditions due to the simple geometry, size, shape and materials used, the further experiments and simulations need to be conducted to determine the true extent that heated walls have on airflow distribution.