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首页> 外文期刊>International Journal of Heat and Mass Transfer >Momentum and heat transfer from a heated circular cylinder in Bingham plastic fluids
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Momentum and heat transfer from a heated circular cylinder in Bingham plastic fluids

机译：Bingham塑料流体中加热圆柱体的动量和热传递

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摘要

In this work, heat and momentum transfer characteristics of a heated circular cylinder submerged in Bingham plastic fluids over wide ranges of conditions as: plastic Reynolds number, 1 ≤ Re ≤ 40, Prandtl number, 1 ≤ Pr≤ 100 and Bingham number, 0 ≤ Bn ≤ 10~4 have been studied numerically. The governing equations in conjunction with the Papanastasiou regularization for the discontinuous-viscosity behavior of a Bingham fluid have been solved using the finite element method. Extensive new results on streamlines, distribution of shear rate and velocity, morphology of yielded/unyielded regions and drag coefficient are presented and discussed to delineate the influence of the fluid yield stress on the structure of flow field. As expected, while the yield stress acts to stabilize the flow by suppressing the phenomenon of flow detachment, the inertial forces act to destabilize the flow. A delicate balance thus exists between the viscous and yield stress effects on one hand and the inertial effects on the other. For a fixed Reynolds number, there exists a critical Bingham number beyond which no flow separation is observed. Also, the laminar forced convection heat characteristics have been analyzed in terms of the isotherm contours, local Nusselt number and average Nusselt number. In order to facilitate the estimation of drag coefficient and Nusselt number in a new application, the present numerical values have been correlated in terms of the pertinent dimensionless parameters with acceptable levels of accuracy. Finally, due to the occurrence of steeper gradients in Bingham plastic fluids otherwise under identical conditions (same Reynolds and Prandtl numbers), the drag is augmented by 37-100% and the Nusselt number by ～30-57% over and above its value in Newtonian fluids (Bn = 0) over the range of conditions spanned here.
机译：在这项工作中，浸在宾厄姆塑性流体中的加热圆柱体的热和动量传递特性在以下条件范围内：塑料雷诺数，1≤Re≤40，普朗特数，1≤Pr≤100和宾厄姆数，0≤ Bn≤10〜4的数值研究。结合宾汉姆流体不连续性行为的Papanastasiou正则化控制方程已使用有限元方法求解。提出并讨论了关于流线，剪切速率和速度的分布，屈服/非屈服区域的形态以及阻力系数的大量新结果，以描述流体屈服应力对流场结构的影响。正如预期的那样，尽管屈服应力通过抑制流分离现象来稳定流，但惯性力却使流不稳定。因此，一方面在粘性和屈服应力效应与另一方面的惯性效应之间存在微妙的平衡。对于固定的雷诺数，存在一个关键的宾厄姆数，超过该值则没有观察到流分离。此外，还根据等温线轮廓，局部努塞尔特数和平均努塞尔特数分析了层流强迫对流热特性。为了便于在新应用中估计阻力系数和Nusselt数，已根据相关的无量纲参数将当前的数值与可接受的精度相关联。最后，由于在相同条件下（相同的雷诺数和普朗特数）在宾厄姆塑性流体中会出现较陡的梯度，因此阻力比其值增加了37-100％，努塞尔特数增加了约30-57％。牛顿流体（Bn = 0）在此处跨越的条件范围内。

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