This paper analyzes the influence of mixed convective fourth grade nanofluid flow by a stretchable Riga device in the presence variable thermal conductivity and mass diffusivity. Heat and mass transportation are considered with Cattaneo–Christov (CC) model. Thermal radiation and dissipation are also taken in the energy expression. Suitable transformation is employed to reduce partial differential system into nonlinear ordinary system. The governing nonlinear expression is solved via optimal homotopy analysis method. Impact of different physical variables is discussed via graphs. Velocity profile is enhanced for higher values of cross viscous parameter and fourth grade fluid variable. Fluid temperature enhances for higher estimation of thermal relaxation parameter but reverse behavior is seen for solutal concentration variable on nanoparticle concentration.

中文翻译：

---

流体流变学对具有热辐射的 riga 装置上四级纳米流体的 Cattaneo-Christov 热通量理论的影响

本文分析了在可变热导率和质量扩散率存在的情况下，可拉伸 Riga 装置对混合对流四级纳米流体流动的影响。Cattaneo-Christov (CC) 模型考虑热量和质量传输。热辐射和耗散也包含在能量表达式中。采用适当的变换将偏微分系统化简为非线性普通系统。通过最优同伦分析方法求解控制非线性表达式。通过图表讨论不同物理变量的影响。对于更高的交叉粘性参数和第四级流体变量值，速度剖面得到了增强。