Flow reversals in particle-dispersed natural convection in a two-dimensional enclosed square domain
Flow reversals in particle-dispersed natural convection in a two-dimensional enclosed square domain
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二维封闭方形域中粒子分散自然对流的流动逆转
DOI：
10.1103/physrevfluids.4.084304
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发表时间：
2019
影响因子：
2.7
通讯作者：
Kajishima Takeo
中科院分区：
文献类型：
--
作者：
Takeuchi Shintaro;Miyamori Yuri;Gu Jingchen;Kajishima Takeo
对二维方箱内颗粒分散两相流自然对流的流动逆转进行了数值模拟研究。基于域边长的瑞利数被设置为。该区域包围了中性浮力的圆形颗粒，颗粒的热导率设定为周围流体的倍。浮力驱动的颗粒分散流发展成循环流，将颗粒输送到区域的对角对角区域。垂直排列在角落区域的颗粒是一个强大的反对流方向的浮力矩的来源，并在几百对流时间尺度的间隔发生流动逆转。这与文献报道的单相自然对流或颗粒分散自然对流中的反转或振荡机理不同。在一个角落里的垂直排列的颗粒的热效应是由无量纲化的热通量建模，和交叉耦合的总和的四个角落被发现是一个前兆指标的反转事件。三个主要参数（瑞利数，电导率比，和平均粒子间距）的影响的调查表明，反转发生在一个小区域中的参数空间。
Flow reversals in natural convection of particle-dispersed two-phase flow in a two-dimensional square box are studied by numerical simulation. The Rayleigh number based on the domain side length is set to. The domain accommodatesneutrally buoyant circular particles, and the thermal conductivity of the particle is set totimes higher than the ambient fluid. The particle-dispersed flow driven by buoyancy develops into circulating flow, which transports particles into a diagonal pair of corner regions of the domain. The particles vertically aligned in the corner regions are a strong source of moment of buoyancy in the counterconvective direction, and flow reversals take place at the intervals of several hundred convective-time scales. The mechanism is different from that of the reversals or oscillation in single-phase or particle-dispersed natural convection reported in the literature. Thermal effect of the vertically aligned particles in a corner is modeled by nondimensionalized heat flux, and a cross-coupled sum of those of the four corners is found to be a precursor indicator of the reversal events. The investigation on the effects of three major parameters (Rayleigh number, conductivity ratio, and average interparticle spacing) suggests that the reversals occur in a small region in the parameter space.