Modelling heat plumes that promote air flow

Cities tend to be subject to the Urban Heat Island (UHI) effect, where they experience higher air and surface temperatures than surrounding rural areas. The negative impacts on public health and thermal comfort are exacerbated with increased urban density, when wind is unable to penetrate densely built-up areas, resulting in large stagnant areas with weak incoming wind.

In cities with limited incoming wind, buoyancy-driven airflow could improve both thermal comfort and air quality outdoors. A study at Future Resilient Systems (FRS) is based on 3D simulation of urban heat plume to better understand the mechanisms of buoyancy-driven airflow and how it could be incorporated in urban planning to promote urban planning.

Prof. Yuan Chao, leader of the Climate Resilience in High-Density Cities research module at FRS programme, and Dr Mei Shuojun from his team at NUS perform turbulence evaluations and turbulence structure analysis to understand the mechanisms of merging heat plumes and the effect on urban climate.

They conducted a study at Newton – one of densest urban areas in Singapore with complex urban geometry – to show the impact of merging heat plumes in high-density urban areas. In this case study, convergence airflow at the pedestrian level is estimated at 2 - 4 metres per second (m/s), which is comparable to wind-driven ventilation. This shows that merging heat plumes can improve thermal comfort and air quality.

This work “external page Three-dimensional simulation of building thermal plumes merging in calm conditions: Turbulence model evaluation and turbulence structure analysis” is published in Building and Environment (October 2021).