Natural Convection in An Open-ended Isothermally-heated Three-dimensional Building Shaft

Abstract

The increased rates of mortality and morbidity in urban areas have been associated with increased levels of pollutant concentration. This study aims at employing natural convection effects to ventilate urban street canyons passively. This is a numerical study, which investigates turbulent three-dimensional natural convection flows in isothermally-heated open-ended building shafts. Five shaft size values {1, 2, 3, 4, 5} m and six temperature difference values {5, 10, 15, 20, 25, 30} C. are taken. Air is modeled as an ideal gas, and the SST k-w model is used for turbulence modeling. The maximum wall y+ value among all cases is 7.2. Results include streamline plots at the entrance of the shaft, average velocity profiles at different elevations, wall heat flux rate profiles, centerline velocity profiles, isotherm plots at different elevations, mass flow rate contours, and a plot of the mass flow rate and total heat rate emitted by the walls. Flow separation occurs in all cases. The mass flow rate generated in the shaft ranges between 1.05-23.53 kg/s, and the total heat rate emitted by the walls ranges between 1.67-91.47 kW.