Large eddy simulations are performed on a fully developed turbulent flow and heat transfer in a square duct with Rayleigh-Benard convection on the basis of the dynamical Smagorinsky eddy viscosity model at turbulent Reynolds number 400 and different Grashof-numbers from 10s to 107. The influences of the buoyancy force on the mean flow, heat transfer and turbulent intensity are analyzed. The results show that the mean velocity decreases while the subgrid viscosity, turbulent intensity and heat transfer increase obviously with an increase in Grashof-number. Moreover, the turbulent intensity in the streamwise direction decreases while the turbulent intensity in the spanwise direction increases clearly near the wall with high temperature because of the buoyancy force. In addition, the initial conditions have a slight influence on the resolved-averaged velocity and temperature distributions but no effect on the mean friction factor and heat transfer coefficient.%基于动态Smagorinsky涡黏模型对矩形通道截面内具有Rayleigh-Benard对流的湍流充分流动和换热问题进行了大涡模拟研究,分析了浮升力对管道截面的平均速度、温度分布以及雷诺应力的影响.湍流雷诺数为400,格拉晓夫数从105变化到107.研究结果表明:随着格拉晓夫数的增大,浮升力增强,通道内平均速度减小;亚格子黏性系数明显增大,湍流强度增强,换热也明显增强;由于浮升力的存在,在高温壁面附近,主流湍动能减小,展向湍流强度大大增强;初始条件对平均速度及温度的分布有一定的影响,但对平均的阻力系数及换热系数没有影响.
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