Wind Loading on Scaled Down Fractal Tree Models of Major Urban Tree Species in Singapore
| Autor: | Daryl Lee, Yong Eng, Woei Leong Chan, Boo Cheong Khoo, Like Gobeawan, Chi Wan Calvin Lim, Yongdong Cui, Zhengwei Ge, Daniel J. Wise, Hee Joo Poh, Daniel C. Burcham |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Drag coefficient
010504 meteorology & atmospheric sciences Geometry Real tree 01 natural sciences frontal area density 010305 fluids & plasmas porous volume symbols.namesake Pythagoras tree 0103 physical sciences particle image velocimetry wind loading 0105 earth and related environmental sciences Wind tunnel large eddy simulation Forestry lcsh:QK900-989 frontal silhouette area Particle image velocimetry Water tunnel Drag symbols lcsh:Plant ecology fractal tree model frontal optical porosity Decision tree model Geology |
| Zdroj: | Forests, Vol 11, Iss 803, p 803 (2020) Forests Volume 11 Issue 8 |
| ISSN: | 1999-4907 |
| Popis: | Estimation of the aerodynamic load on trees is essential for urban tree management to mitigate the risk of tree failure. To assess that in a cost-effective way, scaled down tree models and numerical simulations were utilized. Scaled down tree models reduce the cost of experimental studies and allow the studies to be conducted in a controlled environment, namely in a wind or water tunnel, but the major challenge is to construct a tree model that resembles the real tree. We constructed 3D-printed scaled down fractal tree models of major urban tree species in Singapore using procedural modelling, based on species-specific growth processes and field statistical data gathered through laser scanning of real trees. The tree crowns were modelled to match the optical porosity of real trees. We developed a methodology to model the tree crowns using porous volumes filled with randomized tetrahedral elements. The wind loads acting on the tree models were then measured in the wind tunnel and the velocity profiles from selected models were captured using particle image velocimetry (PIV). The data was then used for the validation of Large Eddy Simulations (LES), in which the trees were modelled via a discretized momentum sink with 10&ndash 20 elements in width, height, and depth, respectively. It is observed that the velocity profiles and drag of the simulations and the wind tunnel tests are in reasonable agreement. We hence established a clear relationship between the measured bulk drag on the tree models in the wind tunnel, and the local drag coefficients of the discretized elements in the simulations. Analysis on the bulk drag coefficient also shows that the effect of complex crown shape could be more dominant compared to the frontal optical porosity. |
| Databáze: | OpenAIRE |
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