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Abstract：
As a novel fluid of functional material, magnetohydrodynamic (MHD) micropolar fluid has the special properties of light, heat, magnetic and so on. It is of highly practical significance. The characteristics of flow, heat and mass transfer in MHD micropolar nanofluid boundary layer past a stretching plate are investigated based on the micropolar fluid theory in the present numerical work. In the presence of magnetic field, viscous dissipation and the cross-diffusion caused by Dufour effect and Soret effect are considered. First order slip velocity condition is employed. Mathematical models are built based on the assumptions. Collocation spectral method (CSM) via matrix multiplication is adopted to solve the two-dimensional dimensionless nonlinear partial governing equations. The program codes based on CSM is developed, validated and employed. The coupled effects of microrotation, Dufour effect, Soret effect, magnetic field as well as first order slip velocity boundary condition on the flow, heat and mass transfer are revealed. Besides, the variation trends of local Nusselt number and Sherwood number are analyzed in detail. The numerical results indicate that the fluid flow can be suppressed obviously in the consideration n of slip condition and magnetic field. As slip parameter δ and magnetic parameter M rise, the velocity in the boundary layer becomes lower gradually; further, both temperature and concentration increase. On the other hand, the opposite trend can be noticed with the effect of material parameter K. Moreover, Ec and Df augment the temperature; while, Sr leads to an upsurge in concentration. The temperature rises by about 79.73% with Dufour effect and Sh enlarges by a factor of about 38.15% with Soret effect. The concentration boundary layer decreases by about 37.50% is when K=5.0.
摘要：
作为一种新型的流体功能材料,磁流体动力学(MHD)微极性流体具有光的特殊性质,热,磁性等等。具有很强的现实意义。流动的特点,基于当前数值工作中的微极性流体理论，研究了经过拉伸板的MHD微极性纳米流体边界层中的传热和传质。在磁场存在的情况下,考虑了Dufour效应和Soret效应引起的粘性耗散和交叉扩散。采用一阶滑移速度条件。数学模型是基于假设建立的。采用矩阵乘法的配置谱方法（CSM）求解二维无量纲非线性部分控制方程。开发了基于CSM的程序代码，验证和使用。微旋转的耦合效应，Dufour效应，Soret效应,磁场以及流的一阶滑移速度边界条件，传热和传质被揭示。此外,详细分析了当地努塞尔数和舍伍德数的变化趋势。数值结果表明，考虑滑移条件和磁场，可以明显抑制流体流动。随着滑移参数δ和磁参数M的上升，边界层中的速度逐渐降低；进一步，温度和浓度都会增加。另一方面,在材料参数K的影响下，可以注意到相反的趋势。Ec和Df增加了温度；而，Sr导致浓度激增。在Dufour效应下，温度升高约79.73％，在Soret效应下，Sh增大约38.15％。当K=5.0时,浓度边界层降低约37.50%。
