臺灣博碩士論文加值系統

The purpose of this study is to examine the possibility of urban design in the aspects of building envelope, arrangement and height to improve the wind and thermal conditions in buildings area on urban community scale in hot-humid climate region. The study compares different urban designed options for a site in Thanh Hoa city, Viet Nam on the micro-climate conditions. The designed options are computationally simulated by two models CFD-ACEs V2006 and ENVI-met 3.1 in order to calculate the potential wind field and air temperature.
Comparison of simulating results shows that the well-designed option for urban community could improve wind and thermal condition by taking advantages of wind channeling effect, Venturi effect, right direction of building to reduce air stagnations, as well as a suitable building height strategy.
- Wind channeling effect could drive wind into and through all streets in community as well as gather air flows to certain place to speed up the wind in that place, reducing the air temperature in street about 2 degrees.
- Suitable building direction can significantly reduce stagnant areas in front of or between buildings, lessening the temperature 2 degrees at same position.
- The Venturi effect appeared in the “Ventury shape” street could increase wind speed at narrower section, make its temperature 1.5 degrees lower that at the street entrance.
- Down-flow in the step-up canyon produces diverged flow from mid of canyon to canyon entrances, while up-flow in the step-down canyon can induce the converged flow from canyon entrances into canyon before is pulled out through canyon roof level.
- Net effect of intersections, where connect the step-up and step-down canyons with wind-parallel street, makes the air temperature generally decreases 1 to 2 degree due to well-mixing of cool air and releasing of heated air out of urban area.

The purpose of this study is to examine the possibility of urban design in the aspects of building envelope, arrangement and height to improve the wind and thermal conditions in buildings area on urban community scale in hot-humid climate region. The study compares different urban designed options for a site in Thanh Hoa city, Viet Nam on the micro-climate conditions. The designed options are computationally simulated by two models CFD-ACEs V2006 and ENVI-met 3.1 in order to calculate the potential wind field and air temperature.
Comparison of simulating results shows that the well-designed option for urban community could improve wind and thermal condition by taking advantages of wind channeling effect, Venturi effect, right direction of building to reduce air stagnations, as well as a suitable building height strategy.
- Wind channeling effect could drive wind into and through all streets in community as well as gather air flows to certain place to speed up the wind in that place, reducing the air temperature in street about 2 degrees.
- Suitable building direction can significantly reduce stagnant areas in front of or between buildings, lessening the temperature 2 degrees at same position.
- The Venturi effect appeared in the “Ventury shape” street could increase wind speed at narrower section, make its temperature 1.5 degrees lower that at the street entrance.
- Down-flow in the step-up canyon produces diverged flow from mid of canyon to canyon entrances, while up-flow in the step-down canyon can induce the converged flow from canyon entrances into canyon before is pulled out through canyon roof level.
- Net effect of intersections, where connect the step-up and step-down canyons with wind-parallel street, makes the air temperature generally decreases 1 to 2 degree due to well-mixing of cool air and releasing of heated air out of urban area.

Table of Contents
Abstract………………………………………………………………………………….i
Acknowledgement…………………………………………………………………...…iii
Table of Contents …………………………………………………………..……..iv - v
List of Figure ……………………………………………………………………....vi - vii
List of Table…………………………………………………………………………...viii
Chapter I. Introduction………………………………………………………………...1
1.1. Introduction………………………….…………………………………………1
1.2 Research purpose………………………………………………………………3
1.3. Content and scope……………………………………………………………..4
1.4 Research processes……………………………………………………….….5
1.5. Study limitations………………………………………………………………6
Chapter II. Literature Review…………………………………………………………..7
2.1. Urban heat island effect………………………………………………………..7
2.1.1.Scale of urban climate……………………………………………….….8
2.1.2. Urban heat island (UHI)……………………………………………….10
2.2. Urban energy transfer………………………………………………………..12
2.3. Urban wind field theory……………………………………………………..14
2.3.1. Building and Wind…………………………………………………….14
2.3.1.1. Single building…………………………………………………....14
2.3.1.2. Group of buildings……………………………………………...16
2.3.2. The cooling effect of wind field on the urban…………………..……18
2.4. Urban geometry……………………………………………………………...19
2.4.1. Building height…………………………………………………….....19
2.4.2. Urban canyon………………………………………………………...19
Chapter III. Research Methods…………………………………………………..……21
3.1. Simulation process………………………………………………………..….21
v
3.2. CFD-ACE+ model……………………………………………………….…..22
3.2.1. Introduction………………………………………………………..….22
3.2.2. Grid generation by CFD-GEOM………………………………..……22
3.2.3. Polyhedral solver CFD-ACE for flow and transfer simulation……….23
3.3. ENVI-met model…………………………………………………………….25
Chapter IV. The Influence of building shape and arrangement on Urban Thermal
Environment……………………………………………………………………….....27
4.1. Designed options………………………………………………………...….28
4.1.1. The studied site………………………………………………….…….28
4.1.2. Computational grid…………………………………………………....31
4.2. CFD simulation boundary conditions………………………………………32
4.3. Simulation result and analysis……………………………………….……..35
4.3.1. Air pathways……………………………………………………………35
4.3.2. The wind velocity within alleys………………………………………37
4.3.3. Street ventilation………………………………………………….….41
4.4. Discussion…………………………………………………………………..42
4.4.1. Wind channeling effect ………………………………………………42
4.4.2. Building direction to avoid frontal stagnation………………….…….45
4.4.3. Ventury effect…………………………………………………………47
Chapter V. Comparison of thermal conditions between building area with equal-height
and varied-height configurations…………………………………………………..…49
5.1. Designed options……………………………………………………………..50
5.1.1. The studied site………………………………………………………..50
5.1.2. Computational grids and boundary conditions…………………………50
5.2. Tunnel experiment and simulation validation………………………………51
5.3. Simulation results and analysis……………………………………….……..56
5.3.1. Wind vertical velocity in canyons…………………………………….57
5.3.2. Wind field inside canyon ……………………………………………. 61
vi
5.3.3. Air temperature distribution……………………………………..….. 65
5.4. Discussion………………………………………………………….…..68
5.4.1. Vertical air exchange ………………………………………………....68
5.4.2. Horizontal air transfer……………………………………………….. 68
5.4.3. Impact of wind to air temperature inside canyons...……………..…69
Chapter VI Conclusions and recommendations……………………………………71
6.1 Conclusion…………………………..……………………………………….71
6.2. Recommendation……………………………………………………..…….. 73
References…………………………………………………………………………....74

References
[1] Ahmad K., Khare M., Chaudhry K.K.. Wind tunnel simulation studies on dispersion at
urban street canyons and intersections—a review. Wind Eng. Ind. Aerod. 2005, 93: 697–717.
[2] Arnfield J. Review two decades of urban climate research: A review of turbulence,
exchanges of energy and water, and the urban heat island. Int. J. Climatol. 2003, 23: 1–26.
[3] Baskaran A., Kashef A. Investigation of air flow around buildings using computational
fluid dynamics techniques. Engineering Structures. 1996, 18: 861-875.
[4] Blocken B., Cameliet J. Pedestrian wind environment around buildings: Literature review
and practical examples. Journal of Thermal Envelope and Building Science. 2004, 28:
107-159.
[5] Blocken B, Carmeliet J, Stathopoulos T. CFD evaluation of the wind speed conditions in
passages between buildings – effect of wall-function roughness modifications on the
atmospheric boundary layer flow. Journal of Wind Engineering and Industrial Aerodynamics.
2007, 95: 941-962.
[6] Blocken B, Stathopoulos T, Carmeliet J. A numerical study on the existence of the
Venturi-effect in passages between perpendicular buildings. Journal of Engineering Mechanics
- ASCE 2008, 134: 1021-1028
[7] Blocken B., Moonen P., Stathopoulos T., Carmeliet J. Numerical Study on the Existence
of the Venturi Effect in Passages between Perpendicular Buildings, J. Eng. Mechan..2008, 134:
1021-1028.
[8] Bruse, M., 1995. Development of a microscale model for the calculation of surface
temperatures in structured terrain. MSc Thesis, Inst. for Geography, Univ. Bochum.
[9] Bruse, M., H. Fleer. Simulating surface-plant-air interactions inside urban environments
with a three dimensional numerical mode. Environ. Modell. Softw. 1998, 13: 373-384.
[10] Edward, Ng., 2010: Designing for Urban Ventilation. Earthscan, 384 pp.
[11] Edward Ng. Towards planning and practical understanding of the need for meteorological
and climatic information in the design of high-density cities: A case-based study of Hong
Kong; International Journal of Climatology. 2012, 32: 582-598.
[12] Eliasson. The use of climate knowledge in urban planning. Landscape and Urban
Planning. 2000, 48: 31-44;
[13] Fazia A., H. Mayer. Numerical study on the effects of aspect ratio and orientation of an
urban street canyon on outdoor thermal comfort in hot and dry climate. Build Environ. 2007,42:
1553-1554.
[14] Gebhart, B., 1959: A new method for calculating radiant exchanges. ASHRAE Trans., 59,
95-104.
75
[15] Giridharana R., S.S.Y. Laua, S. Ganesana, B. Givoni. Urban design factors influencing
heat island intensity in high-rise high-density environments of Hong Kong. Building and
Environment. 2007, 42: 3669–3684.
[16] Givoni B., Climate considerations in building and urban design (1998).
[17] Golany G.S. Urban design morphology and thermal performance. Atmospheric
Environment. 1996, 30: 45-65.
[18] Gross, G. Anwendungsmo glichkeiten mesoskaliger Simulationsmodelle dargestellt am
Beispiel Darmstadt. Meteorologie Rundschau. 1991, 43: 97–112.
[19] Huang, H., Ryozo Ooka, Shinsuke Kato. Urban thermal environment measurements and
numerical simulation for an actual complex urban area covering a large district heating and
cooling system in summer. Atmos. Environ. 2005, 39, 6362-6375.
[20] Hupfer P. Das Klimasystem Der Erde, Akademie-Verlag. Berlin. 1991: 464.
[21] Hupfer, P., 1996: Unsere Umwelt. Das Klima. (Our Environment. Climate), Stuttgart,
Leipzig.
[22] Ishizaki H. and Sung I. W. Influence of adjacent building to wind. Proc. 3rd Int. Conf. on
Wind Effects on Buildings and Structures, Tokyo .1971.
[23] Jian Hang, Yuguo Li, Mats Sandberg, Leif Claesson. Wind conditions and ventilation in
high-rise long street models. Building and Environment. 2010, 45: 1353–1365.
[24] Li X., Yu Z., Zhao B., Li Y. Numerical analysis of outdoor thermal environment around
buildings. Build Environ. 2005, 40: 853-866.
[25] Lin Hsien Teh , 1994. 現代人類的居住環境（生活環境科學之一）
[26] Lin Hsien Teh , 2009. 人居熱環境
[27] Lin T.P., Richard D., Hwan R.L. Effect of thermal adaptation on seasonal outdoor
thermal comfort. Int. J. Climatol. 2011, 31: 302–312.
[29] Mellor, G.L., Yamada, T. A simulation of the Wangara atmospheric boundary layer data. J.
Atmos. Sci. 1975, 32: 2309–2329.
[30] Mill G. Luke Howard and The Climate of London. Weather. 2007, 63: 153-157.
[31] Mirzaei P.A., Haghighat F. Approaches to study Urban Heat Island e Abilities and
limitations. Building and Environment. 2010, 45: 2192-2201.
[32] Oke T.R. Canyon geometry and the nocturnal urban heat island: comparison of scale
model and field observations. Int. J. Climatol. 1981, 1: 237-254.
[33] Oke T.R. The energetic basis of the urban heat island. Quart. J. R. Met. Soc. 1987, 108:
1-24;
[34] Oke TR. Street design and urban canopy layer climate. Energy Build. 1988, 11: 103–113.
[35] Peterke J.A., Meroney R.N., Kothari K.M., Wind flow pattern about buildings, Journal
of Wind Engineering and Industrial Aerodynamics, 21 (1985) 21-38;
[36] Priyadarsini R., Wong N.H., Cheong K. W. Microclimatic modeling of the urban thermal
environment of Singapore to mitigate urban heat island. Solar Energy. 2008, 82: 727-745.
76
[37] Sheail M. Thepapers of ProfessorGordonManley. Weather. 1985, 40: 22–23.
[38] Sketch of an Urban Heat-Island Profile (www.nasa.gov)
[39] Song C.C. Computation of Wind Flow around a Tall Building and the Large--Scale
Vortex Structure, Journal of Wind Engineering and Industrial Aerodynamics, 46 &
47 (1993) 219-228;
[40] Stathopoulos T., Storms R. Wind environmental conditions in passages between
buildings. Journal of Wind Engineering and Industrial Aerodynamics. 1986, 24: 19-31.
[41] Stathopoulos T., Wu H., Berdard C. Wind environment around building: a
knowledge-based approach. J. Wind Egn Int. Aerodyn. 1992: 2377-2388.
[42] Stathopoulos T., Hanqing Wu. Generic models for pedestrian-level winds in built-up
regions. Journal of Wind Engineering and Industrial Aerodynamics 1995, 54-55: 515-525.
[43] Soulhac, L., V. Garbero, P. Salizzoni, P. Mejean, R.J. Perkins. Flow and dispersion in
street intersections. Atmos. Environ. 2009, 43: 2981-2996.
[44] Taesler, R., Anderson, C. A method for solar radiation computings using routine
meteorological observations. Energy Build. 1984, 7: 341–352.
[45] To A.P., Lam K.M. Evaluation of pedestrial-level winds in environment around a row of
tall buildings using a quatile-level wind speed descriptor. J. Wind Egn Int. Aerodyn. 1995,
54-55: 527-541.
[46] Tsang C.W., Kwok K.C.S., Hitchcock P.A. Wind tunnel study of pedestrian level wind
environment around tall buildings: Effects of building dimensions, separation and podium.
Build Environ. 2012, 49: 167-181.
[47] Yoshihito K., Tadahiro Tuchikawab, Jin Ishii, Kenta Fukagawaa, Yoshiaki Yamatoc,
Naoki Matsubara. Radiative and convective heat transfer coefficients of the human body in
natural convection. Building and Environment. 2008, 43: 2142–2153.
[48] UN-World Urbanization Prospect. 2005.
[49] Vietnamese Construction Ministry, 2011: Vietnamese National Housing Development
Strategy period 2011 - 2020, further vision to 2030.
[50] Vietnamese Construction Ministry, 2009: QCXDVN 02-2009, Vietnamese Building Code
for Natural physical & Climatic data for Construction.
[51] Voogt J.A, Oke T.R. Thermal remote sensing of urban climates, Journal of Remote
Sensing of Environment. 2003, 86: 370–384.
[52] Wiren B.G. A wind tunnel study of wind velocities in passages between and through
buildings. Proc. 14th Int Conf. on Wind Effects on Buildings and Sructures, Healthrow, UK.
1975: 465-475.