Purpose

This study aims to investigate the flow impinging on a stagnation point of a shrinking cylinder subjected to prescribed surface heat flux in Al₂O₃-Cu/water hybrid nanofluid.

Design/methodology/approach

Using similarity variables, the similarity equations are obtained and then solved using bvp4c in MATLAB. The effects of several physical parameters on the skin friction and heat transfer rate, as well as the velocity and temperature profiles are analysed and discussed.

Findings

The outcomes show that dual solutions are possible for the shrinking case, in the range λc<λ<−1, where λc is the bifurcation point of the solutions. Meanwhile, the solution is unique for λ≥−1. Besides, the boundary layer is detached on the surface at λc, where the value of λc is affected by the hybrid nanoparticle φhnf and the curvature parameter γ. Moreover, the friction and the heat transfer on the surface increase with the rising values φhnf and γ. Finally, the temporal stability analysis shows that the first solution is stable in the long run, whereas the second solution is not.

Originality/value

The present work considers the problem of stagnation point flow impinging on a shrinking cylinder containing Al₂O₃-Cu/water hybrid nanofluid, with prescribed surface heat flux. This paper shows that two solutions are obtained for the shrinking case. Further analysis shows that only one of the solutions is stable as time evolves.

中文翻译：

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具有规定表面热通量的收缩圆柱体上的混合纳米流体流

目的

本研究旨在研究在Al ₂ O ₃ -Cu /水杂化纳米流体中，在规定的表面热通量作用下，收缩流停滞在收缩圆柱体上的流动。

设计/方法/方法

使用相似变量，获得相似方程，然后在MATLAB中使用bvp4c求解。分析和讨论了几个物理参数对皮肤摩擦和传热速率以及速度和温度分布的影响。

发现

结果表明，在范围缩小的情况下，双重解决方案是可能的 λC<λ<-1个， 在哪里 λC是解决方案的分歧点。同时，该解决方案是唯一的 λ≥-1个。此外，边界层在 λC，其中的价值 λC 受杂化纳米粒子的影响 φHñF 和曲率参数 γ。此外，表面上的摩擦和热传递随着值的增加而增加 φHñF 和 γ。最后，时间稳定性分析表明，从长远来看，第一个解决方案是稳定的，而第二个解决方案则不是。

创意/价值

本工作考虑了停滞点流撞击具有规定表面热通量的，包含Al ₂ O ₃ -Cu /水杂化纳米流体的收缩圆柱体的问题。本文表明针对收缩情况获得了两种解决方案。进一步的分析表明，随着时间的流逝，只有一种解决方案是稳定的。