Roşca Natalia C, Pop Ioan
Department of Mathematics, Faculty of Mathematics and Computer Science, Babeş-Bolyai University, 400084 Cluj-Napoca, Romania.
Entropy (Basel). 2021 Jun 25;23(7):813. doi: 10.3390/e23070813.
The present paper studies the flow and heat transfer of the hybrid nanofluids flows induced by a permeable power-law stretching/shrinking surface modulated orthogonal surface shear. The governing partial differential equations were converted into non-linear ordinary differential equations by using proper similarity transformations. These equations were then solved applying a numerical technique, namely bvp4c solver in MATLAB. Results of the flow field, temperature distribution, reduced skin friction coefficient and reduced Nusselt number were deduced. It was found that increasing mass flux parameter slows down the velocity and, hence, decreases the temperature. Furthermore, on enlarging the stretching parameter, the velocity and temperature increases and decreases, respectively. In addition, that the radiation parameter can effectively control the thermal boundary layer. Finally, the temperature decreases when the values of the temperature parameter increases. We apply similarity transformation in order to transform the governing model into a system of ODEs (ordinary differential equations). Numerical solutions for particular values of involved parameters are in very good agreement with previous calculations. The most important and interesting result of this paper is that for both the cases of shrinking and stretching sheet flows exhibit dual solutions in some intervals of the shrinking and stretching parameter. In spite of numerous published papers on the flow and heat transfer over a permeable stretching/shrinking surface in nanofluids and hybrid nanofluids, none of the researchers studied the present problem. Therefore, we believe that the results of the present paper are new, and have many industrial applications.
本文研究了由可渗透幂律拉伸/收缩表面调制的正交表面剪切引起的混合纳米流体流动的流动与传热问题。通过适当的相似变换将控制偏微分方程转换为非线性常微分方程。然后应用一种数值技术,即MATLAB中的bvp4c求解器来求解这些方程。推导了流场、温度分布、约化表面摩擦系数和约化努塞尔数的结果。研究发现,增加质量通量参数会使速度减慢,从而降低温度。此外,增大拉伸参数时,速度增加而温度降低。另外,辐射参数可以有效地控制热边界层。最后,温度参数值增大时温度降低。我们应用相似变换以便将控制模型转换为常微分方程组。所涉及参数特定值的数值解与先前的计算结果非常吻合。本文最重要且有趣的结果是,对于收缩和拉伸片材流动这两种情况,在收缩和拉伸参数的某些区间内都呈现出双解。尽管已经发表了大量关于纳米流体和混合纳米流体中可渗透拉伸/收缩表面上的流动与传热的论文,但没有研究人员研究过当前这个问题。因此,我们认为本文的结果是新颖的,并且有许多工业应用。