Purpose

The purpose of this paper is to study the laminar boundary layer cross flow and heat transfer on a rotational stagnation-point flow over either a stretching or shrinking porous wall submerged in hybrid nanofluids. The involved boundary layers are of stream-wise type with stretching/shrinking process along the surface.

Design/methodology/approach

Using appropriate similarity variables the partial differential equations are reduced to ordinary (similarity) differential equations. The reduced system of equations is solved analytically (by high-order perturbed field propagation for small to moderate stretching/shrinking parameter and low-order perturbation for large stretching/shrinking parameter) and numerically using the function bvp4c from MATLAB for different values of the governing parameters.

Findings

It was found that the basic similarity equations admit dual (upper and lower branch) solutions for both stretching/shrinking surfaces. Moreover, performing a linear stability analysis, it was confirmed that the upper branch solution is realistic (physically realizable), while the lower branch solution is not physically realizable in practice. These dual solutions will be studied in the present paper.

Originality/value

The authors believe that all numerical results are new and original and have not been published before for the present problem.

中文翻译：

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交叉流和热传递通过杂化纳米流体中的可渗透拉伸/收缩片

目的

本文的目的是研究层状边界层的交叉流动和旋转滞留点流上的传热和传热，该旋转滞留点流是浸没在混杂纳米流体中的拉伸或收缩多孔壁上。涉及的边界层是沿流方向的，具有沿表面的拉伸/收缩过程。

设计/方法/方法

使用适当的相似性变量，将偏微分方程简化为普通（相似）微分方程。简化的方程组可以通过解析方法解决（对于小至中等的拉伸/收缩参数，通过高阶扰动场传播；对于大的拉伸/收缩参数，通过低阶扰动来解），并使用MATLAB的bvp4c函数对不同的控制值进行数值求解。参数。

发现

已经发现，基本相似性方程式对两个拉伸/收缩表面都允许双重（上部和下部分支）解决方案。此外，通过进行线性稳定性分析，已确认上部分支解决方案是现实的（物理上可实现的），而下部分支解决方案在实践中是物理上无法实现的。这些双重解决方案将在本文中进行研究。

创意/价值

作者认为，所有数值结果都是新的和原始的，因此尚未针对当前问题发表过。