摘要:对具有复杂下垫面的小区精细化风环境进行数值模拟是当前城市气象研究的热点，而针对具有复杂地形的山地型城市（如重庆）的研究还比较匮乏。本文采用能显式分辨下垫面陡峭地形和复杂建筑物的计算流体力学（CFD）模式对重庆市渝北区龙湖社区气候态下的精细化风环境进行高分辨率的数值模拟。结果表明，下垫面能显著调节小区内风场的分布，风速大值区主要出现在九龙湖等开阔区域以及与中尺度背景入流方向一致的街道中。在夏季，小区整体风场以东南风为主，而其他3个季节则以偏东风为主。4个季节中，夏季小区内的风速最大，平均风速为0.3 m/s左右，局地能出现大于背景风的风速，可达0.8 m/s；其他3个季节的风速则较弱，区域平均的风速在0.2 m/s左右。不同的建筑物布局对局地风环境的影响也不同：单个孤立高层建筑迎风面的近地面存在明显地绕流，局地风速有所增加，而在背风面则形成尾流区，水平风速较低；在低矮分散的建筑群，建筑物的整体高度不高，区域内流场相对来说比较一致，风速较大，有利于小区的通风；在密集高层建筑群内，由于建筑物群本身的布局比较封闭，加之不同建筑物的环流场存在相互干扰及影响，使得小区近地面风速几乎为零，不利于小区通风和污染物扩散。建筑物的这些影响在城市冠层内尤为明显，高度越高这种影响越弱。
关键词:复杂下垫面/
风环境/
精细化特征/
计算流体力学
Abstract:Super-high-resolution numerical simulations on the wind environment in neighborhoods have been a hot research area in urban meteorology. In this study, a computational fluid dynamics model based on large-eddy simulation was utilized to simulate the climatic wind environment in Longhu Community in Chongqing, and the impacts of local building configurations on the fine-scale structures of the wind field was investigated. Results show that complex underlying surfaces played an important role in regulating local circulations. The strong winds were mainly found over open spaces and at broad streets parallel to the background inflow. The overall wind speed in summer was larger than that in other seasons and could reach a magnitude of 0.8 m/s. Different building configurations led to different patterns of local wind fields. The isolated tall building resulted in strong downward motions and winding flows at the windward side of the building, where strong winds frequently occurred. The scattered low buildings had little impact on the local inflow, resulting in a wind field with a homogeneous pattern. The densely built tall complex with an enclosing shape greatly blocked the wind, which led to a relatively weak wind speed in the vicinity and was unfavorable for pollutant dispersion.
Key words:Complex underlying surfaces/
Wind environment/
Fine-scale structures/
Computational fluid dynamics (CFD)
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