Thermal convection with strongly temperature-dependent viscosity
Thermal convection with strongly temperature-dependent viscosity
复制标题
热对流，粘度与温度密切相关
DOI：
--
复制
发表时间：
1976
影响因子：
3.7
通讯作者：
J. Booker
中科院分区：
文献类型：
--
作者：
J. Booker
本文通过实验研究了高普朗特数流体层中的热传输和对流结构，该流体层的粘度在边界温度之间变化高达 300 倍。瑞利数 R 的适当定义使用顶部和底部边界温度的平均值的粘度。在刚性边界和从下方加热的情况下，随着粘度比的增加，用恒定粘度流体的努塞尔数 N0 归一化的努塞尔数 N 略有下降。变化为 300 时下降了 12%。N/N0 对 R 的轻微依赖性与关系式 N ∝ Rβ 中的指数从 R [lsim ] 5 × 104 的恒定粘度值 0·281 到 0·25 的下降一致。这可能与从三维流向二维流的转变有关。在 R ∼ 105 和粘度变化为 150 时，细胞结构仍然由边缘稳定状态的水平波长主导。对于自由和刚性上限都是如此。流动是强三维的，具有自由的上边界，而它是近二维的，具有刚性的上边界。
This paper experimentally investigates the heat transport and structure of convection in a high Prandtl number fluid layer whose viscosity varies by up to a factor of 300 between the boundary temperatures. An appropriate definition of the Rayleigh number R uses the viscosity at the average of the top and bottom boundary temperatures. With rigid boundaries and heating from below, the Nusselt number N normalized with the Nusselt number N0 of a constant-viscosity fluid decreases slightly as the viscosity ratio increases. The drop is 12% at a variation of 300. A slight dependence of N/N0 on R is consistent with a decrease in the exponent in the relation N ∝ Rβ from its constant-viscosity value of 0·281 to 0·25 for R [lsim ] 5 × 104. This may be correlated with a transition from three- to two-dimensional flow. At R ∼ 105 and viscosity variation of 150, the cell structure is still dominated by the horizontal wavelength of the marginally stable state. This is true with both free and rigid upper boundaries. The flow is strongly three-dimensional with a free upper boundary, while it is nearly two-dimensional with a rigid upper boundary.