Predicting the influence of subtropical trees on urban wind through wind tunnel tests and numerical simulations

Senlin Zheng, Jean Michel Guldmann, Zhixin Liu, Lihua Zhao*, Junsong Wang, Xueli Pan, Dongfang Zhao

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Better prediction of turbulent airflow around urban trees is necessary because it impacts urban pollutant dispersion, outdoor thermal comfort, energy efficiency, pedestrian-level comfort and urban heat island mitigation. A major challenge is how to obtain an accurate numerical model of the turbulent flow field around trees and an improved parameterization of the turbulent momentum deficit using the drag coefficient (Cd). To address this challenge, we use wind tunnel tests and real trees to measure Cd for four common subtropical tree species: Ficus microcarpa, Mangifera indica, Michelia alba and Bauhinia blakeana. The results show that the Cd of the four trees ranges from 0.523 to 0.932, and that the negative relationship between Cd and wind speed (U) can be expressed by the exponential formula Cd=a*U−b. A three-dimensional model of wind modification by trees is proposed, and its accuracy is verified with wind tunnel measurements. With precise Cd and model, the predictability of the influence of trees on urban wind in subtropical areas is enhanced (root mean square error RMSE ranging from 2.89 m/s to 0.45 m/s). Future development and applications of the numerical model will help provide useful guidelines for urban landscape management and sustainable urban planning in terms of urban ventilation.

Original languageEnglish
Article number102116
Pages (from-to)1-11
Number of pages11
JournalSustainable Cities and Society
Early online date26 Feb 2020
Publication statusPublished - Jun 2020


  • Tree drag coefficient
  • Turbulent flow model
  • Urban heat island
  • Urban ventilation
  • Wind tunnel test

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