Study on Flow Properties of Convective Boundary Layer over Thermally Inhomogeneous Surface

Abstract

Abstract:

The simulation of convective boundary layer (CBL) over thermally inhomogeneous surface is made using water tank for study on flow properties. By imitating the mosaic method in the numerical simulation, the low thermal conductivity materials are placed on the bottom of the water tank so that heating from the bottom is inhomogeneous. The CBL height and velocity scales are obtained by temperature profiles and collimated-laser system. PTV technique is used for retrieval of two dimensional flow fields. The flow fields have complex structure and scales. Compared with the homogeneous surface, the surface inhomogeneous heating makes the mixed layer strengthen turbulence organization and have stable local circulations. The variations of statistics of velocities with height are different from the homogeneous situation. In order to analyze the contribution of thermal inhomogeneity to the horizontal advection, the turbulent advections for turbulent kinetic energy are calculated. Results show that at the beginning and developing period the horizontal advection is large due to the large heating difference and the horizontal advection becomes weak at the end of development of CBL due to the little heating difference. Based on these results, it can be concluded that the horizontal advection depends on the thermally inhomogeneous intensity.

Key words: convective boundary layer, thermal inhomogeneity, water tank, horizontal advection

CLC Number:

P264

YUAN Ren-Min, LUO Chao, WU Xu-Ping, LU Chao, LIU Hui-Zhi. Study on Flow Properties of Convective Boundary Layer over Thermally Inhomogeneous Surface[J]. Journal of Atmospheric and Environmental Optics, 2009, 4(6): 421-431.

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