Data sources: statistical annals of Chongqing in 2003
2. CFD Introduction
2.1 PHOENICS Introduction 
2.2 PHOENICS Mathematical Model Basement
2.2.1 Fluid-flow Control Equation 
2.2.2 κ – ε Turbulent Model
- RNG κ – ε turbulent modelThe way of RNG are suitable to large scale, and influences of the small scale are described through improving the transferring coefficient. The RNG κ – ε model made a great progress with the disadvantage of overhigh value of vortex viscosity in the primary κ – ε. Furthermore, this RNG model can give an accurate simulation to dissociation and associative fluid-flow. However, it can not give a correct result with jet stream fluid and feather fluid. The RNG κ – ε model amends some of the constant values, and one item is added to the ε model as equation 2-3.
- Chen-Kim κ – ε turbulent modelIt is the model amended by Chen and Kim in 1987 aiming at avoiding the disadvantages of sing-time-scale in primary κ – ε model. The dynamic effect of ε equation is improved through increasing an external time-scale item under following:Chen-Kim κ – ε model not only keeps the merits of RNG κ – ε model but also have nice results happening to jet stream fluid and feather fluid.
- LVEL turbulent modelLVEL is the unique model in PHOENICS and it belongs to zero equation models. It adopts Spalding wall law to compute νi and is the same with a number of solid blocks arranged in room, three-dimensional questions as well. This LVEL model is suitable to the low Reynolds.
3.1. Field Measurement
3.2. Simulations and Analysis
3.3. Validations of the consistency between field measurement and simulation
3.4. Brief Summary
- The influence of high-rise building to the wind field: it is not obvious in the field measurement because of too many factors including predominant wind direction, brush-fire wind and underlying roughness. Furthermore, the measuring points are always at the height of 1.5m above ground. However, we can see clearly from the simplified simulation model that the predominant wind is blocked directly by the high-rise building, which finally induces a large low speed area in the southeast. Besides, there is “stagnant water region” near auditorium between two annexes where the wind speed is less than 0.5m/s.Two ways can be selected to strength the ventilation effect around the high-rise building: one is widening the air channels in the North-South trend of the building. Because the main roads near the high-rise building are always in the East-West trend, and both simulated values and measuring results show that the speed is much higher in the North-South trend; the other is to channel wind holes through the annex which could make the northwest and southeast wind go through the building so as to decrease the area of the stagnant water region.
- The influence of air-conditioning heat: high-rise buildings are big heat sources, the simulated results which are with air-conditioning heat show that the temperature of the surroundings especially along the predominant wind direction can be 1°C higher than other regions and this influence continues to beyond. The higher the outdoor atmospheric temperature, the higher air-conditioning burden is. That is to say, it is easy to form a vicious circle. Therefore, it is necessary to build a large green area region as well as water area in the downwind areas which can not only absorb the air-conditioning heat but decrease the stay of personnel.
4. Discussions and Improvement
4.1. Influences of different architectural compositions to wind environment
4.2. Different architectural layouts
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|region||GDP per capital /$||Land area /km2||Total population /thousand||nonagricultural population /thousand||Population density/person/km2||Level of urbanization/%|
|Three gorges ecological zone||7,503||1564.31||2129.8||581024.9||5853||13.6|
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