Modelling the cooling effectiveness of street trees with actual canopy drag and real transpiration rate under representative climatic conditions

Abstract

Computational fluid dynamics has proven itself as a versatile tool to study various urban physics phenomena and develop urban heat island adaptation strategies. This study is based on the development of new parameterization related to aerodynamic and thermal effects of urban vegetation; and their implementation in CFD to study its effectiveness in improving the thermal environment with approximately 100 trees having canopy width/height of 9 m. A more realistic consideration of these parameters is required to improve the quality/accuracy of CFD results. The study results show that vegetation, modeled with these developed parameters (i.e. actual form drag coefficient and variable tree transpiration rate), yields significant variation in micro-climatological results, as causes a reduction of 1.2 K and 0.9 K; 4.0 K and 1.8 K in air temperature and surface temperature respectively. The tree, modeled with the actual form drag coefficient, has highest impact in reducing velocity i.e. upto 0.5 m/sec.