非定常耦合应力磁性纳米流体在具有欧姆耗散的拉伸片上流动的计算研究

IF 4.2 Q2 NANOSCIENCE & NANOTECHNOLOGY
Mahesh Kumar, G. J. Reddy, N. N. Kumar, O. Bég
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引用次数: 20

摘要

为了更深入地了解磁性纳米聚合物材料制造中固有的输运现象,在本研究中,我们建立了一个数学模型,用于研究在横向静态磁场存在下拉伸片上随时间变化的流体磁流变纳米聚合物边界层流动和热传递。焦耳加热(欧姆耗散)和粘性热效应也包括在内,因为这些现象在磁性材料加工中经常出现。采用Stokes耦合应力模型模拟非牛顿微观结构特征。采用Tiwari-Das纳米尺度模型,该模型允许模拟不同的纳米颗粒(在本文中,铜-水和氧化铝-水纳米流体都被考虑在内)。利用相似变换将控制偏微分守恒方程转换为具有适当壁面和自由流边界条件的耦合非线性常微分方程系统。采用射击技术,通过MATLAB符号软件求解简化非线性耦合常微分边值问题。验证与发表的结果,从文献包括非耗散和牛顿纳米流体流动的特殊情况。当非牛顿耦合应力参数和磁参数较大时,铜和氧化铝纳米流体的速度和温度曲线均增强,而非定常参数较大时,流体速度和温度曲线则相反。边界层流动随着浮力参数、弹性板拉伸参数和对流参数的增大而加速。温度通常随耦合应力流变参数的增大而升高,并且氧化铝纳米颗粒的温度始终较高。温度也随着磁性参数的增加而升高,当磁性参数超过单位(磁力超过粘性力)时,温度在壁面附近出现超调。随着板材拉伸参数的增大,温度降低。埃克特数的增加使温度显著升高。随着纳米颗粒体积分数的增加,表面摩擦和努塞尔数都增加,并且铜纳米颗粒达到比氧化铝更高的量级。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Computational study of unsteady couple stress magnetic nanofluid flow from a stretching sheet with Ohmic dissipation
To provide a deeper insight of the transport phenomena inherent to the manufacturing of magnetic nano-polymer materials, in the present work a mathematical model is developed for time-dependent hydromagnetic rheological nano-polymer boundary layer flow and heat transfer over a stretching sheet in the presence of a transverse static magnetic field. Joule heating (Ohmic dissipation) and viscous heating effects are included since these phenomena arise frequently in magnetic materials processing. Stokes’ couple stress model is deployed to simulate non-Newtonian microstructural characteristics. The Tiwari–Das nanoscale model is adopted which permits different nanoparticles to be simulated (in this article, both copper–water and aluminium oxide–water nanofluids are considered). Similarity transformations are utilized to convert the governing partial differential conservation equations into a system of coupled, non-linear ordinary differential equations with appropriate wall and free stream boundary conditions. The shooting technique is used to solve the reduced non-linear coupled ordinary differential boundary value problem via MATLAB symbolic software. Validation with published results from the literature is included for the special cases of non-dissipative and Newtonian nanofluid flows. Fluid velocity and temperature profiles for both copper and aluminium oxide (Al2O3) nanofluids are observed to be enhanced with greater non-Newtonian couple stress parameter and magnetic parameter, whereas the opposite trend is computed with greater values of unsteadiness parameter. The boundary layer flow is accelerated with increasing buoyancy parameter, elastic sheet stretching parameter and convection parameter. Temperatures are generally increased with greater couple stress rheological parameter and are consistently higher for the aluminium oxide nanoparticle case. Temperatures are also boosted with magnetic parameter and exhibit an overshoot near the wall when magnetic parameter exceeds unity (magnetic force exceeds viscous force). A decrease in temperatures is induced with increasing sheet stretching parameter. Increasing Eckert number elevates temperatures considerably. With greater nanoparticle volume fraction, both skin friction and Nusselt number are elevated, and copper nanoparticles achieve higher magnitudes than aluminium oxide.
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来源期刊
CiteScore
6.00
自引率
1.70%
发文量
24
期刊介绍: Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems is a peer-reviewed scientific journal published since 2004 by SAGE Publications on behalf of the Institution of Mechanical Engineers. The journal focuses on research in the field of nanoengineering, nanoscience and nanotechnology and aims to publish high quality academic papers in this field. In addition, the journal is indexed in several reputable academic databases and abstracting services, including Scopus, Compendex, and CSA's Advanced Polymers Abstracts, Composites Industry Abstracts, and Earthquake Engineering Abstracts.
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