Abstract This study investigates the laminar unsteady natural convection in a square enclosure with an internal circular cylinder containing non-Newtonian fluid. The results illustrate the effect of vertical movement of an internal circular cylinder on the flow and heat transfer mechanism within a square enclosure for Rayleigh numbers ranging from 103 to 106. The Prandtl number was fixed to 10. The internal cylinder was positioned at three different locations along the vertical center line near the isothermal bottom wall, at the center, and near the isothermal top wall. The effect of the power law index in the range of 0.6 to 1.6 with a step size of 0.2 on the natural convection is also examined with respect to other parameters. The numerical solution was unsteady symmetric for “at the center” case and unsteady asymmetric for “near the isothermal bottom wall” and “near the isothermal top wall” cases at n = 0.6 for Ra = 106.

中文翻译：

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充满非牛顿流体的方形外壳内自然对流的非定常分析

摘要 本研究调查了方形外壳中的层流非定常自然对流，该外壳具有包含非牛顿流体的内部圆柱体。结果说明了内部圆柱体的垂直运动对方形外壳内的流动和传热机制的影响，瑞利数范围为 103 到 106。普朗特数固定为 10。内部圆柱体位于三个不同的位置沿垂直中心线靠近等温底壁，在中心，靠近等温顶壁。在 0.6 到 1.6 的范围内，步长为 0.2 的幂律指数对自然对流的影响也相对于其他参数进行了检查。