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对流边界层大涡模式的改进及对夹卷速度的研究
引用本文:苗世光,蒋维楣,李昕,刘衡.对流边界层大涡模式的改进及对夹卷速度的研究[J].大气科学,2001,25(1):25-37.
作者姓名:苗世光  蒋维楣  李昕  刘衡
作者单位:1.南京大学大气科学系,南京210093
基金项目:国家自然科学基金资助项目49775257和中国科学院重大项目KZ952-S1-405共同资助
摘    要:对已建的对流边界层(CBL)大涡模式进行了改进,将次网格闭合方案改为次网格能量闭合,并考虑了水汽的源汇项和水汽相变潜热的作用。通过对均匀下垫面上由热扰动发展的对流边界层的模拟及与实验结果的比较表明,模式较好地模拟了对流边界层的主要物理结构,较好地反映了各物理量之间的对应关系。本文在一定的对流理查森数(Ri*)范围内给出了一些算例,对无量纲夹卷速度(We/W*)进行了研究。结果表明,无量纲夹卷速度随地表热通量(Qs)的增大而增大,随对流边界层上部温度递减率(γ)的增大而减小。当9.06≤Ri*≤45.29时,无量纲夹卷速度We/W*可以拟合成A(Ri*)-1的形式,其中A=0.226。并且与我们的对流槽实验结果,Sullivan等人的大涡模拟结果以及Deardorff等人的对流槽实验结果作了比较,四者吻合较好。

关 键 词:对流边界层    大涡模拟    夹卷速度    理查森数

Improvements of the Large Eddy Simulation Models and a Study of the Entrainment Rate
Miao Shiguang,Jiang Weimei,Li Xin and Liu Heng.Improvements of the Large Eddy Simulation Models and a Study of the Entrainment Rate[J].Chinese Journal of Atmospheric Sciences,2001,25(1):25-37.
Authors:Miao Shiguang  Jiang Weimei  Li Xin and Liu Heng
Abstract:A previous large eddy simulation (LES) model of convective boundary layer (CBL) is improved, in place of the original subgrid closure scheme with energy closure scheme and considers water vapour source, sink and the effect of the latent heat due to phase change of water vapour. The simulation of CBL increasing as a result of the thermal disturbance on the homogeneous terrain and comparison with the results of the experiment display that the model simulates the main physical structure of CBL effectively and reflects the corresponding relationship among several physical variables.Over a certain range of bulk Richardson numbers, Ri*, some cases are calculated to study the dimensionless entrainment rate, We/W*. We can see from the results that the dimensionless entrainment rate, We / W*, increases with the increasing of the thermal flux on the ground, Qs, and decreases with the increasing of the temperature lapse rate above the CBL. The dimensionless entrainment rate, We / W*, where We and W* are entrainment and convective velocities, varies as A Ri * withA = 0.226 in the range of 9.06≤ Ri * ≤ 45.29 and is in good agreement with our convection tank experiment, the LES by Sullivan et al. and the convection tank measurements by Deardorffet al.
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