Purpose

This paper aims to accentuate the behavior of second-grade hybrid Al₂O₃–Cu nanofluid flow and its thermal characteristics driven by a stretching/shrinking Riga plate.

Design/methodology/approach

The second-grade fluid is considered with the combination of Cu and Al₂O₃ nanoparticles. Three base fluids namely water, ethylene glycol (EG) and methanol with different Prandtl number are also examined. The formulation of the mathematical model of second-grade hybrid nanofluid complies with the boundary layer approximations. The complexity of the governing model is reduced into a simpler differential equations using the similarity transformation. The bvp4c solver is fully used to solve the reduced equations. The observation of multiple solutions is conducted for the assisting (stretching) and opposing (shrinking) cases.

Findings

The impact of suction parameter, second-grade parameter, electromagnetohydrodynamics (EMHD) parameter, velocity ratio parameter and the volumetric concentration of the alumina and copper nanoparticles are numerically analyzed on the velocity and temperature profiles, skin friction coefficient and local Nusselt number (thermal rate) of the second-grade Al₂O₃–Cu/water. The solution is unique when (static and stretching cases) while dual for a specific range of negative in the presence of suction effect. Based on the appearance of the first solution in all cases of, it is physically showed that the first solution is stable. Further examination reveals that the EMHD and suction parameters are the contributing factors for the thermal enhancement of this non-Newtonian working fluid. Meanwhile, the viscosity of the non-Newtonian fluid also plays a significant role in the fluid motion and heat transfer rate based on the finding that the EG base fluid produces the maximum heat transfer rate but the lowest critical value and skin friction coefficient.

Originality/value

The results are novel and contribute to the discovery of the hybrid nanoparticles’ performance in the non-Newtonian second-grade fluid. Besides, this study is beneficial to the researchers in this field and general audience from industries regarding the factors, which contributing to the thermal enhancement of the working fluid.

中文翻译：

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Riga板诱导的二级杂化纳米流体的驻点流动

目的

本文旨在强调二级混合 Al ₂ O ₃ -Cu 纳米流体流动的行为及其由拉伸/收缩 Riga 板驱动的热特性。

设计/方法/方法

二级流体被认为是Cu和Al ₂ O ₃纳米粒子的组合。还检查了三种基础流体，即具有不同普朗特数的水、乙二醇 (EG) 和甲醇。二级杂化纳米流体数学模型的建立符合边界层近似。使用相似变换将控制模型的复杂性降低为更简单的微分方程。bvp4c 求解器完全用于求解简化方程。对辅助（拉伸）和相反（收缩）情况进行了多种解决方案的观察。

发现

数值分析了吸力参数、二级参数、电磁流体力学（EMHD）参数、速度比参数以及氧化铝和铜纳米粒子的体积浓度对速度和温度曲线、皮肤摩擦系数和局部努塞尔数（热速率）的影响。 ) 的二级 Al ₂ O ₃–铜/水。该解决方案在（静态和拉伸情况下）是独特的，而在存在吸力效应的情况下，针对特定范围的负向双重解决方案。基于第一溶液在所有情况下的出现，物理上表明第一溶液是稳定的。进一步研究表明，EMHD 和吸力参数是这种非牛顿工作流体热增强的促成因素。同时，基于EG基础流体产生最大传热率但最低临界值和皮肤摩擦系数的发现，非牛顿流体的粘度对流体运动和传热率也起着重要作用。

原创性/价值

该结果是新颖的，有助于发现混合纳米粒子在非牛顿二级流体中的性能。此外，本研究有助于该领域的研究人员和行业的普通观众了解有助于工作流体热增强的因素。