Purpose

Ferrofluids are aqueous or non-aqueous solutions with colloidal particles of iron oxide nanoparticles with high magnetic characteristics. Their magnetic characteristics enable them to be controlled and manipulated when ferrofluids are exposed to magnetic fields. This study aims to inspect the features of unsteady stagnation point flow (SPF) and heat flux from the surface by incorporating ferromagnetic particles through a special kind of second-grade fluid (SGF) across a movable sheet with a nonlinear heat source/sink and magnetic field effect. The mass suction/injection and stretching/shrinking boundary conditions are also inspected to calculate the fine points of the features of multiple solutions.

Design/methodology/approach

The leading equations that govern the ferrofluid flow are reduced to a group of ordinary differential equations by applying similarity variables. The converted equations are numerically solved through the bvp4c solver. Afterward, study and discussion are carried out to examine the different physical parameters of the characteristics of nanofluid flow and thermal properties.

Findings

Multiple solutions are revealed to happen for situations of unsteadiness, shrinking as well as stretching sheets. Greater suction slows the separation of the boundary layers and causes the critical values to expand. The region where the multiple solutions appear is observed to expand with increasing values of the magnetic, non-Newtonian and suction parameters. Moreover, the fluid velocity significantly uplifts while the temperature declines due to the suction parameter.

Originality/value

The novelty of the work is to deliberate the impact of mass suction/injection on the unsteady SPF through the special second-grade ferrofluids across a movable sheet with an erratic heat source/sink. The confirmed results provide a very good consistency with the accepted papers. Previous studies have not yet fully explored the entire analysis of the proposed model.

中文翻译：

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由 Fe3O4 颗粒引起的特殊二级流体的非稳态滑流通过具有磁性和非线性热源/汇的可移动片

 目的

铁磁流体是具有高磁性特征的氧化铁纳米粒子胶体颗粒的水性或非水性溶液。当铁磁流体暴露在磁场中时，它们的磁性特性使得它们能够被控制和操纵。本研究旨在通过一种特殊的二级流体 (SGF) 将铁磁颗粒掺入具有非线性热源/散热器和磁性的可移动片材上，以检查非稳态驻点流 (SPF) 和表面热通量的特征。场效应。还检查质量吸/注入和拉伸/收缩边界条件，以计算多个解的特征的细点。

设计/方法论/途径

通过应用相似变量，控制铁磁流体流动的主要方程被简化为一组常微分方程。转换后的方程通过 bvp4c 求解器进行数值求解。随后，进行了研究和讨论，考察了不同物理参数对纳米流体流动特性和热性能的影响。

 发现

对于不稳定、收缩以及拉伸板材的情况，有多种解决方案。更大的吸力会减慢边界层的分离并导致临界值扩大。观察到出现多个解的区域随着磁性、非牛顿和吸力参数值的增加而扩大。此外，由于吸力参数，流体速度显着升高，而温度下降。

 原创性/价值

这项工作的新颖之处在于，通过具有不稳定热源/散热器的可移动片材上的特殊二级铁磁流体，研究质量抽吸/注射对不稳定 SPF 的影响。确认的结果与已接受的论文具有非常好的一致性。先前的研究尚未充分探索所提出模型的整个分析。