海岸城市上空热力内边界层的基本特征

发布时间：2018-07-07 16:05

本文选题：热力内边界层 + 海岸城市　；参考：《力学学报》2016年02期

【摘要】：海岸热力内边界层内大气在热力驱动下产生垂向对流运动,对海岸带的大气运动规律产生深刻的影响.在海岸城市地区,受城市冠层复杂结构的影响,热力内边界层呈现诸多独特的性质.采用大涡模拟的方法,研究了海岸城市热力内边界层内的流动特征.将海岸城市建筑物拟形为一系列有序排列的立方体块,并基于浸入边界方法考虑其对大气流动的影响.和常见的区域尺度数值研究中将城市下垫面假设为均质属性平面的方法相比,模拟结果的精度明显提高,海岸热力内边界层内各种尺度的动力过程也能在一定程度上得以描述.模拟计算了海岸城市热力内边界层、中性海岸城市边界层和开阔的自然海岸热力内边界层共3种情况,对比研究了城市摩阻和海岸热力作用对海岸城市上空大气运动的影响.研究结果表明:在空间上,边界层中各紊流特征量均在街谷尺度呈现出有规律而非均匀分布的特点;在强度上,热力作用与城市构筑物的摩阻作用相互促进,使得紊流强度显著提升并大于两种作用线性叠加的结果.此外,还发现有城市冠层海岸的热力内边界层发展远快于相同热力条件下的自然海岸带,边界层的发展规律也有显著的不同.
[Abstract]:The vertical convection movement of the atmosphere in the inner boundary layer of the coasts is driven by heat, which has a profound influence on the atmospheric movement in the coastal zone. In coastal urban areas, the thermal inner boundary layer presents many unique properties due to the complex structure of urban canopy. The characteristics of flow in the thermal boundary layer of coastal cities are studied by means of large eddy simulation. The coastal urban buildings are modeled as a series of ordered cube blocks, and their effects on the atmospheric flow are considered based on the immersion boundary method. Compared with the common numerical method in which the urban underlying surface is assumed to be a homogeneous attribute plane, the accuracy of the simulation results is obviously improved, and the dynamic processes of various scales in the thermal inner boundary layer of the coast can be described to a certain extent. The thermal inner boundary layer of coastal city, neutral coastal city boundary layer and open natural coastal thermal inner boundary layer are simulated and calculated. The effects of urban friction and coastal thermal action on the atmospheric movement over coastal cities are compared and studied. The results show that, in space, the characteristic quantities of turbulence in the boundary layer are regular and not uniformly distributed in the scale of the street valley, and in the intensity, the thermodynamic action and the friction action of the urban structure promote each other, and the characteristic quantity of the turbulent flow in the boundary layer shows the characteristics of regular and non-uniform distribution in the scale of the street valley. The turbulence intensity is significantly increased and larger than the result of the linear superposition of the two actions. In addition, it is found that the thermal inner boundary layer of the urban canopy coast develops much faster than that of the natural coastal zone under the same thermal conditions, and the law of the boundary layer development is also significantly different.
【作者单位】：清华大学水利水电工程系水沙科学与水利水电工程国家重点实验室;
【基金】：国家自然科学基金资助项目(11472156)
【分类号】：P732

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