Abstract

Extensive results are reported on the flow and heat transfer for Bingham plastic fluids for the same configuration as in Part I over the ranges: Reynolds number $\left(5\mathrm{}-\mathrm{}200\right),$ Prandtl number $\left(1-100\right),$ and Bingham number $\left(0.01-100\right)$ and the gap ratio $\left(0.3\mathrm{}-\mathrm{}0.7\right).$ At small Bingham numbers, the results deviate a little from that in Newtonian fluids except for the pockets of unyielded material. With the increasing fluid yield stress, the flow field consists of preferred flow channels between the inlet and outlet ports with high shear zones which directly influence the drag and Nusselt number. Depending upon the extent of fluid yielding, the drag on the middle cylinder can be higher by up to ∼100% or lower by up to ∼90% than that on the upstream cylinder. Similarly, the strong back flow observed at low Bingham numbers and high Reynolds numbers in the rear of the downstream cylinder leads to negative drag. In sparse arrays, the drag of upstream and downstream cylinders is comparable but that on the middle cylinder is always smaller. Similarly, the average heat transfer coefficient for each successive cylinder decreases with respect to the upstream cylinder. For the upper and downstream cylinder, this ratio is about 28-65% depending upon the kinematic conditions. In most cases, the first cylinder offers the maximum heat transfer.

摘要

对于与第一部分中相同配置的宾汉塑性流体的流动和传热，在以下范围内报告了广泛的结果：雷诺数 $\left(5\mathrm{}-\mathrm{}200\right),$ 普朗特数 $\left(1-100\right),$ 和宾汉数 $\left(0.01-100\right)$ 和差距比 $\left(0.3\mathrm{}-\mathrm{}0.7\right).$在较小的宾汉数下，结果与牛顿流体中的结果略有不同，除了未屈服材料的口袋。随着流体屈服应力的增加，流场由入口和出口之间的优选流动通道组成，具有直接影响阻力和努塞尔数的高剪切区。根据流体屈服的程度，中间圆柱体上的阻力可以比上游圆柱体上的阻力高约 100% 或低至 90%。同样，在下游圆柱体后部在低宾汉数和高雷诺数下观察到的强回流导致负阻力。在稀疏阵列中，上游和下游圆柱体的阻力相当，但中间圆柱体的阻力总是较小。相似地，每个连续气缸的平均传热系数相对于上游气缸降低。对于上下游气缸，根据运动条件，该比例约为 28-65%。在大多数情况下，第一个气缸提供最大的热传递。