Analysis of ZnO-SAE50 nanolubricant performance under variable thermal conductivity and solar radiations: Model for bidirectional stretchable surface

Analysis of thermal transport in nanolubricants is an interesting and potential topic. Hence, the current research focuses on the study of ZnO-SAE50 by adding the major effects of variable thermal conductivity, combined convection, and thermal radiations. The physical set up is designed for 3D dimensional flow through a surface and then investigated the results via numerical scheme. From detailed analysis of the physical results, it is examined that ZnO concentration and suction effects cause reduction in the fluid movement while for stretching case these variations are quite rapid than shrinking case. Further, the combined convective effects greatly influenced the fluid motion over the surface. The velocity $G^{\prime }\left(\eta \right)$ increases rapidly under increasing Grashof effects and maximum motion is observed for stretching case. The temperature of ZnO-SAE50 enhanced due to increasing thermal radiations and ZnO concentration. However, minimal changes are investigated under variable thermal conductivity number $ϵ$, shterching/shrinking $\lambda$ and maximum drop in the temperature is examined due to stronger Grashof number effects.