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Wind Loading on Scaled Down Fractal Tree Models of Major Urban Tree Species in Singapore
- Source :
- Forests, Vol 11, Iss 803, p 803 (2020), Forests, Volume 11, Issue 8
- Publication Year :
- 2020
- Publisher :
- MDPI AG, 2020.
-
Abstract
- 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<br />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.
- Subjects :
- 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
Subjects
Details
- Language :
- English
- ISSN :
- 19994907
- Volume :
- 11
- Issue :
- 803
- Database :
- OpenAIRE
- Journal :
- Forests
- Accession number :
- edsair.doi.dedup.....633ec5722fcb1ee0f74b0ea13f61b92a