| Author: | Li, Guangyin |
| Title: | Numerical analysis on the thermal impact of vegetation on air flow in street canyon |
| Degree: | M.Eng. |
| Year: | 2012 |
| Subject: | Plant-atmosphere relationships. Computational fluid dynamics. Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building Services Engineering |
| Pages: | xi, 77 leaves : ill. ; 30 cm. |
| Language: | English |
| Abstract: | On account of the express urbanization, microclimate inside street canyons has been in the spotlight. Urban planners attempted to mitigate the problem by introducing vegetation as a kind of compensation to environmental drawbacks. However, the overall ecological effect of vegetation is still not clear. Although the beneficial influence of vegetations on thermal comfort and dynamic field for pedestrians in street canyon has been discussed in both site measurements and wind tunnel experiments, but further developments in the aspect of the computational simulations are still needed to determine the impacts in practical applications. This paper introduces a numerical approach based on the computational fluid dynamics (CFD) models, the code FLUENT. The model considers vegetations in canyon as porous materials, and the Rossland radiation model is employed to combine with thermal conduction using standard and realizable k-ε turbulence models. After validating with the previous experimental data, with-tree models have been built based on without-tree models. In order to identify the optimum arrangement of street trees, a number of parameters were investigated, including of street canyon aspect ratio(H/W=1 and 2), crown types (9m length×9m weigh×9m height and 9m length×4.5m weigh×9m height), green coverage (12.5%, 25% and 50% ) and solar orientations (at 9 a.m., 12 a.m. and 3 p.m.). According to comparisons among the situations of street canyons with tree or without tree, this paper reveals the tendencies of average temperature and velocity in the pedestrian zone. Results from this study reveal the impacts of vegetation in street canyons and determine a reasonable density of vegetation planting for urban thermal environment control. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b25255587.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.73 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/6642