Council on Tall Buildings and Urban Habitat

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1 CFD Simulation of Urban Pedestrian Wind Comfort Optimization in High-Rise Building Cluster - Case Study Li Kuishan Ph.D, East China Architectural Design & Research Institute Co

2 目录 CONTENTS 研究背景 Research Background 基础理论 Basic Theory 案例介绍 Case Study 结论建议 Results and Recommendation

3 研究背景 Research Background

4 研究背景 Research Background 上海陆家嘴 Shanghai Lujiazui 美国纽约 New york 中国香港日本东京 China Hongkong Japan Tokyo

研究背景 Research Background 有利影响 1. 改善区域风环境, 提高舒适性 ; 2. 改善室内自然通风, 降低建筑能耗 ; 3. 促进区域内污染物扩散, 改善区域内部空气品质 Advantage 1.

To reduce concentration of pollution SO 2 (mg/m 3 ) 0.10 0.08 0.06 0.04 0.02 0.

恶劣的风环境影响周边商店客流 ; 4. 国外相关报道, 由于风速过大, 引起两位妇女死亡 Disadvantage 1.Existing buildings 2.Building itself 3.

5 研究背景 Research Background 有利影响 1. 改善区域风环境, 提高舒适性 ; 2. 改善室内自然通风, 降低建筑能耗 ; 3. 促进区域内污染物扩散, 改善区域内部空气品质 Advantage 1.To improve comfort. 2.To improve indoor natural ventilation and reduce energy consumption. 3. To reduce concentration of pollution SO 2 (mg/m 3 ) Average Max Source : 城市绿地与风的环境效应研究, 中国园林, 不利影响 1. 对已有建筑的不利影响 ; 2. 建筑群本身存在问题 ; 3. 恶劣的风环境影响周边商店客流 ; 4. 国外相关报道, 由于风速过大, 引起两位妇女死亡 Disadvantage 1.Existing buildings 2.Building itself 3. Shops that are left untenanted because of the windy environment that discouraged shoppers. 4. Two old ladies after being blown over by sudden wind gusts near a high-rise building.

6 研究背景 Research Background 数值模拟 Numerical Simulation 风洞实验 Wind Tunnel

7 研究背景 Research Background

8 基础理论 Basic Theory

9 基础理论 Basic Theory Computing domain Inlet Comparison of different guideline AIJ (Architectural Institute of Japan) U (z) =U s (z/z s ) α I (z) =0.1(z/z G ) (-α-0.05) k (z) =(I(z)U(z)) 2 ε (z) =C 0.5 µ k (z) U sα (z/z s ) α-1 /z s COST C14 (European Cooperation in the field of Scientific and Technical Research) U(z)=U* ABL ln((z+z 0 )/z)/κ k(z)= U * ABL 2 / C µ 0.5 ε(z)= U* ABL3 / (κ(z+z 0 )) U* ABL =κu h /ln((h+z 0 )/z) Wall z0 ks should meet the logarithmic law z0 ks should meet the logarithmic law Turbulence model Grid Solution 5H max 5H max H max 10H max H max 5H max 15H W max 5H max Revise k-e and DSM minium of 10 grids on one side of a building;the ratio of the adjacent grids of 1.3 or less;more than 3 grids at the 1.5m height Scaled residuals/mass and energy conservation /monitor point 2.3W 5H max Improved k-e with the linear eddy viscosity assumption minimum of 10 grids on one side of a building; ratio of the adjacent grids of 1.3 or less; more than 3 grids at the 1.5m height Scaled residuals (10-4 )/ mass and energy conservation /monitor point Source: Yoshihide Tominaga, Akashi Mochida, Ryuichiro Yoshie, Hiroto Kataoka, Tsuyoshi Nozu, Masaru Yoshikawa, Taichi Shirasawa. AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. Journal of Wind Engineering and Industrial Aerodynamics 96 (2008)

10 基础理论 Basic Theory Wind tunnel testing Numerical simulation Validation Alternative Question? Domain Grid Model Boundary Boundary Velocity(m/s) Experiment Simulation Point Percent Converge

基础理论 Basic Theory 计算区域 Computing domain Inlet Outlet Source: Yoshihide Tominaga, Akashi Mochida, Ryuichiro Yoshie, Hiroto Kataoka, Tsuyoshi Nozu, Masaru Yoshikawa, Taichi

11 基础理论 Basic Theory 计算区域 Computing domain Inlet Outlet Source: Yoshihide Tominaga, Akashi Mochida, Ryuichiro Yoshie, Hiroto Kataoka, Tsuyoshi Nozu, Masaru Yoshikawa, Taichi Shirasawa. AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. Journal of Wind Engineering and Industrial Aerodynamics 96 (2008)

12 基础理论 Basic Theory 网格控制 Independent grid solution 模型 Model 初始网格 Initial mesh 优化网格 Refine mesh 1.5m height at least 3-4 grids Finalize mesh 10 grids

13 基础理论 Basic Theory 湍流模型 Turbulence models Comparison of different models Large Eddy Simulation Standard k-ε two equations RNG k-ε two equations RSM k-ε two equations Realizable k-ε two equations Time consuming k is usually overrated at the Stagnation point Time consuming Time consuming Meets the engineering accuracy requirements

14 基础理论 Basic Theory 湍流模型 Turbulence models [mm] mm Source:

15 基础理论 Basic Theory Velocity(m/s) Velocity(m/s) 湍流模型 Turbulence models Experiment Simulation Point 标准 k-ε 模型, 一阶迎风差分 Standard k-ε first order upwind scheme Experiment Simulation Percent Percent Velocity(m/s) Velocity(m/s) Experiment Simulation Point RNG k-ε 模型, 一阶迎风差分 RNG k-ε first order upwind scheme Experiment Simulation Percent Percent [mm] mm Point 0.0 RNG k-ε 模型, 二阶迎风差分 RNG k-ε second order upwind scheme Point Realizable k-ε 模型, 二阶迎风差分 Realizable k-ε second order upwind scheme 0.0

16 基础理论 Basic Theory 入口边界 Atmospheric Boundary Layer H=500m H=500m H=50m H=10m X=0m X=100m X=500m X=1000m X=10000m 入口大气边界层风速廓线 Inlet atmospheric boundary layer

17 基础理论 Basic Theory 壁面边界 Wall Function Y p P ABL log law? Wall function? 矛盾 Contradiction 壁面 wall 1.5m height At least 3-4 grid 至少3-4 个网格

18 基础理论 Basic Theory 边界设置 Principal 整个流场分为三个区域, 进口段核心段出口段 ; 建筑的区域划分为核心区 ; The entire flow field can be divided into three regions, the upstream region, the core region, downstream region. 尽量缩短入口段的距离 ; Reducing as much as possible the upstream length of the computational domain will limit the development of stream wise gradients. 降低入口处壁面附近的湍动能 ; To artificially lower the turbulent kinetic energy at the inlet to decrease the momentum transfer between the fluid layers which in turn decreases the acceleration of the wind speed near the surface. 使用修正过的 k-e 方程, 采用 UDS 修正 k e 方程并编写程序从而代替商业软件 (Fluent) 中标准 k e 方程 Giving up the two-equation model of the standard commercial software, correcting the k and e equation by UDS. 入口区 Upstream region 核心区 core region NNW 15 NW 10 NWW 5 W 0 SWW 出口区 Downstream region N NNE NE SW SE SSW SSE S wind speed in winter NEE E SEE

19 基础理论 Basic Theory 树木模型 Tree model field velocity k

20 基础理论 Basic Theory Beaufort number Description 1 Light air 2 Light breeze 3 Gentle breeze 4 Moderate breeze 5 Fresh breeze 6 Strong breeze 7 High wind, moderate gale, near gale Wind speed m/s m/s m/s m/s m/s m/s m/s Land conditions Smoke drift indicates wind direction and wind vanes cease moving. Wind felt on exposed skin. Leaves rustle and wind vanes begin to move. Leaves and small twigs constantly moving, light flags extended. Dust and loose paper raised. Small branches begin to move. Branches of a moderate size move. Small trees in leaf begin to sway. Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic bins tip over. Whole trees in motion. Effort needed to walk against the wind. Sea state 8 Gale, fresh gale m/s Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded. Beaufort scale: From Wikipedia, the free encyclopedia

21 案例研究 Case Study

22 案例介绍 Case Study APEC 低碳城市示范项目 Low Carbon Model Town (LCMT)

23 案例介绍 Case Study By :SOM

25 Case 1

26 Case 2

27 Case 3

28 案例介绍 Case Study 计算域 Computing domain

29 案例介绍 Case Study 计算域 Computing domain

30 案例介绍 Case Study

31 案例介绍 Case Study

32 案例介绍 Case Study 不同工况对比 Comparison of different cases Case 1 Case 2 Case 3

33 案例介绍 Case Study 不同工况对比 Comparison of different cases Case 1

34 案例介绍 Case Study 不同工况对比 Comparison of different cases Case 2

35 案例介绍 Case Study 不同工况对比 Comparison of different cases Case 3

36 案例介绍 Case Study Comparison of different cases Case 1 Case 2 Case 3

37 结论建议 Result and Recommendation Comparing case 1 and case 2, it is obvious that greening design strategy improves air distribution and decrease eddy region. However, such green-planting planning will enlarge the uncomfortable area, especially in summer, what s more, it is difficult for the pollution dispersing around the buildings for the reason of the low-velocity. It is clear that case 3 is best for outdoor air distribution for the reason of changing greenplanting area. It is recommended that low vegetation, grass, trees should be planted in prevailing wind direction and densely built-up areas.this greening strategy will be good for air distribution as well as pollution dilution. However, high trees are suitable for coastal garden along the river. Further research on the heat island

38 Thank you for your attention

Zoomlion Concrete Placing Boom HG28G,HG28E. Zoomlion Concrete Placing Boom (without counterweight) HG28G HG28E (proportional control)

Zoomlion Concrete Placing Boom (without counterweight) HG28G HG28E (proportional control) 1 The history of HG28G & HG28E Zoomlion used to manufacture and sell HG28D separate placing boom in China market,