Momentum and Heat Transfer over Urban-like Surfaces
Momentum and Heat Transfer over Urban-like Surfaces
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DOI：
10.1007/s10546-009-9381-7
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发表时间：
2009-06-01
影响因子：
4.3
通讯作者：
Moriizumi, Takanobu
中科院分区：
文献类型：
--
作者：
Kanda, Manabu;Moriizumi, Takanobu
在综合室外比例模型（COSMO）实验中，研究了城市样表面的动量和传热。同时和比较气象测量是在两个不同块几何的比例模型上进行的。通过对这些数据的分析，探讨了砌块的高度变化、障碍物伸长率和堆积密度（lambda (p)）对气动性能的影响。此外，还检验了动量和热量的体积传递系数理论表达式相对于几何参数的鲁棒性。我们的分析表明：(1)动量体传递系数C (m)和热量体传递系数C (h)的理论框架适用于均匀建筑阵列；(2)C (h)对表面几何形状的敏感性小于C (m);(3)传递系数随砌块高度的变化而增加，但不受砌块伸长的影响；(4)采用简单的理论假设，考虑高度变化的影响，可以得到两种不同高度的块体阵列的C (m)和C (h)的一阶近似；(5)块体高度的变化显著增加了动量通量，但对感热通量的影响很小。这可以用气动-热相互作用的反馈机制来解释；气动混合降低了对流速度和垂直温度梯度。
Momentum and heat transfer was examined for the urban-like surfaces used within the Comprehensive Outdoor Scale MOdel (COSMO) experiments. Simultaneous and comparative meteorological measurements were made over a pair of scale models with different block geometries. These data were analyzed to investigate the influence of height variations, obstacle elongation, and packing density, lambda (p) , of blocks on the aerodynamic properties. In addition, the robustness of theoretical expressions of bulk transfer coefficients for momentum and heat with respect to geometric parameters was examined. Our analyses showed: (1) the theoretical framework for the bulk transfer coefficient for momentum, C (m) , and that for heat, C (h) , was applicable for homogeneous building arrays, (2) the sensitivity of C (h) to the surface geometry was smaller than that of C (m) , (3) the transfer coefficients were increased by variations of block heights, but not by elongation of blocks, (4) first-order approximations of C (m) and C (h) for an array of blocks with two different heights can be made by applying simple theoretical assumptions to include the effects of height variation, and (5) variations of block heights increased the momentum flux significantly, but caused little change in the sensible heat flux. This can be explained by the feedback mechanism of aerodynamic- thermal interaction; aerodynamic mixing decreased both the advective velocity and the vertical temperature gradient.