Purpose

The main purpose of this study is to present a non-similar analysis of two-dimensional boundary layer flow of non-Newtonian nanofluid over a vertical stretching sheet with variable thermal conductivity. The Sisko fluid model is used for non-Newtonian fluid with an exponent (n* > 1), that is, shear thickening fluid. Buongiorno model for nanofluid accounting Brownian diffusion and thermophoresis effects is used to model the governing differential equations.

Design/methodology/approach

The governing boundary layer equations are converted into nondimensional coupled nonlinear partial differential equations using appropriate transformations. The resultant differential equations are solved numerically using implicit finite difference scheme in association with the quasilinearization technique.

Findings

This analysis shows that the temperature raises for thermal conductivity parameter and velocity ratio parameter while decreases for the thermal buoyancy parameter. The thermophoresis and Brownian diffusion parameter that characterizes the nanofluid flow enhances the temperature and reduces the heat transfer rate. Skin friction drag can be effectively reduced by proper control of the values of thermal buoyancy and velocity ratio parameter.

Practical implications

The wall heating and cooling investigation result in the analysis of the control parameters that are related to the designing and manufacturing of thermal systems for cooling applications and energy harvesting. These control parameters have practical significance in the designing of heat exchangers and solar thermal collectors, in glass and polymer industries, in the extrusion of plastic sheets, the process of cooling of the metallic plate, etc.

Originality/value

To the best of authors’ knowledge, it is found from the literature survey that no similar work has been published which investigates the non-similar solution of Sisko nanofluid with variable thermal conductivity using finite difference method and quasilinearization technique.

中文翻译：

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具有可变热导率的Sisko纳米流体流的非相似解：有限差分法

目的

这项研究的主要目的是对导热率可变的垂直拉伸片材上非牛顿纳米流体的二维边界层流动进行非相似分析。Sisko流体模型用于指数（n *> 1）的非牛顿流体，即剪切增稠流体。用Buongiorno模型计算纳米流体的布朗扩散和热泳效应，对控制微分方程进行建模。

设计/方法/方法

使用适当的变换，将控制边界层方程转换为无量纲耦合的非线性偏微分方程。结合准线性化技术，使用隐式有限差分方案对所得的微分方程进行数值求解。

发现

分析表明，温度对于导热系数和速度比参数升高，而对于热浮力参数降低。表征纳米流体流动的热泳和布朗扩散参数提高了温度并降低了传热速率。通过适当控制热浮力和速度比参数的值，可以有效减少皮肤摩擦阻力。

实际影响

墙体加热和冷却调查的结果是对与冷却应用和能量收集的热系统的设计和制造有关的控制参数进行了分析。这些控制参数在热交换器和太阳能集热器的设计，玻璃和聚合物行业，塑料板的挤出，金属板的冷却过程等方面具有实际意义。

创意/价值

据作者所知，从文献调查中发现，尚未发表类似的工作，该研究使用有限差分法和准线性化技术研究了导热系数可变的Sisko纳米流体的非相似溶液。