二维方腔热对流羽流流动特性及平均场传热特性研究  

Plume movement characteristics and heat transfer characteristics in 2-D thermal convection

作　　者：宁浩[1] 包芸[1] 

机构地区：[1]中山大学应用力学与工程系,广州510275

出　　处：《水动力学研究与进展（A辑）》2013年第2期184-189,共6页Chinese Journal of Hydrodynamics

摘　　要：本文进行了二维Rayleigh-Bénard热对流数值研究。在非等距网格上用二阶中心差分格式,并采用跳线迭代的半隐式格式求解压力泊松方程。在Pr 4.3情况下,计算了8个Ra数(2×105 Ra 2×109)的热对流场。计算结果表明:在热对流发生的初始阶段,蘑菇状羽流先在方腔内的边角位置产生,然后在方腔顶底边中部产生;不同的Ra数初始羽流数不同,Ra数越大,初始的蘑菇状羽流数越多。在热对流充分发展的流动阶段,当Ra数较小时(2×105 Ra 2×106),流动不稳定,较大尺度的羽流来回穿梭致使方腔中心涡流动不停翻转;当Ra数变大时(2×107 Ra 2×109),羽流流动形成稳定角涡,方腔中部形成了稳定的大尺度中心涡。并计算了各个Ra数迭代100万次的平均场温度边界层厚度和Nu数,得出了温度边界层厚度d与Ra数和Nu数与Ra数只有对数律关系的结论。Abstract： This paper presents the numerical study of two-dimensional Rayleigh-Bénard convection. The jumping-line iterative scheme was used to solve the pressure Poisson equation with second-order central difference scheme on the non-equidistant grids. For Pr= 4.3, the thermal convection field with eight Ra Numbers （2×10^5≤Ra 2×10^9） was calculated. The results show that in the initial stage, the mushroom-shaped plumes occurs at the comers of the square cavityfirst and then in the middle of the bottom and top. The number of plumes is different for the different Ra number. It is found that the larger the Ra number the more the mushroom-shaped plumes. In the fully developed flow stage, when the Ra number is small （2×10^5 ≤Ra 2×10^6）, two large-scale plume move back and forth, and the vortex in the center of the square cavity flips, but when the Ra number is large （2×107 ≤Ra 2×10^9）, a stable large-scale circulation at the center of the square cavity and the comer vortex are formed by the plume flow. The temperature boundary layer thickness and Nu number for 8 cases are calculated from the average field with 1,000,000 iterative. The temperature boundary layer thickness and the Nu number both have a logarithmic law relationship with the Ra number.

关 键 词：RB热对流 羽流流动特性 传热特性 数值计算 

分 类 号：O357.53[理学—流体力学]