Oscillations of the large-scale circulation in turbulent mixed convection in a closed rectangular cavity
Oscillations of the large-scale circulation in turbulent mixed convection in a closed rectangular cavity
复制标题
封闭矩形空腔内湍流混合对流大尺度环流的振荡
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
C. Wagner
中科院分区：
文献类型：
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作者：
D. Schmeling;J. Bosbach;C. Wagner
流体温度时间序列是在立方体对流槽内特定位置的湍流混合对流中记录的。它们揭示了大尺度流动结构的不稳定性，大尺度流动结构在阿基米德数的中间范围内组织热量传输，其中浮力和惯性力具有相似的强度。这种不稳定性导致了三个和四个对流辊之间的周期性或自发的转变。此外，对于高瑞利数或雷诺数，流动分别由浮力或惯性力控制，形成稳定的大尺度环流(LSC)。在中间Ra-Re数区域，我们将这种复杂的动力学归因于天花板压力驱动的壁射流与浮力驱动的LSC的相互作用，这种复杂的动力学在温度时间序列中可见振荡。最大主振荡频率比壁面喷流诱导环流涡旋或热致LSCS的翻转频率小一个数量级左右。结果进一步表明，通过调节流入速度，即雷诺数，可以控制LSC的周期性重构，从而产生稳定的LSC。
Fluid temperature time series are recorded in turbulent mixed convection at specific locations inside a cuboidal convection cell. They reveal instabilities of the large-scale flow structures, which organise the heat transport in an intermediate range of Archimedes numbers, where buoyancy and inertia forces are of similar strength. The instabilities lead to periodic or spontaneous transitions between three and four convection rolls. Further, for either high Rayleigh or Reynolds numbers, for which the flow is either governed by buoyancy or by inertia forces, respectively, stable large-scale circulations (LSCs) develop. In the intermediate Ra–Re number regime, we ascribe the complex dynamics, visible as oscillation in the temperature time series, to the interaction of the pressure-driven wall jet at the ceiling with the buoyancy-driven LSCs. The maximal main oscillation frequency is about one order of magnitude smaller than the turnover frequencies of either the wall jet-induced circulation rolls or thermally induced LSCs. It is further shown that the periodic reconfigurations of the LSCs can be controlled by adjusting the inflow velocity, that is, the Reynolds number, to generate stable LSCs.