The Effect of Thermophoresis on Unsteady Oldroyd-B Nanofluid Flow over Stretching Surface

A Comprehensive Review of Non-Newtonian Nanofluid Heat Transfer

Nanofluids behave like non-Newtonian fluids in many cases and, therefore, studying their symmetrical behavior is of paramount importance in nanofluid heat transfer modeling. This article attempts to provide are flection on symmetry via thorough description of a variety of non-Newtonian models and further provides a comprehensive review of articles on non-Newtonian models that have applied symmetrical flow modeling and nanofluid heat transfer. This study reviews articles from recent years and provides a comprehensive analysis of them. Furthermore, a thorough statistical symmetrical analysis regarding the commonality of nanoparticles, base fluids and numerical solutions to equations is provided. This article also investigates the history of nanofluid use as a non-Newtonian fluid; that is, the base fluid is considered to be non-Newtonian fluid or the base fluid is Newtonian, such as water. However, the nanofluid in question is regarded as non-Newtonian in modeling. Results show that 25% of articles considered nanofluids with Newtonian base fluid as a non-Newtonian model. In this article, the following questions are answered for the first time: Which non-Newtonian model has been used to model nanofluids? What are the most common non-Newtonian base fluids? Which numerical method is most used to solve non-Newtonian equations?

Heat Transfer Enhancement in Unsteady MHD Natural Convective Flow of CNTs Oldroyd-B Nanofluid under Ramped Wall Velocity and Ramped Wall Temperature

This article analyzes heat transfer enhancement in incompressible time dependent magnetohydrodynamic (MHD) convective flow of Oldroyd-B nanofluid with carbon nanotubes (CNTs). Single wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) are immersed in a base fluid named Sodium alginate. The flow is restricted to an infinite vertical plate saturated in a porous material incorporating the generalized Darcy’s law and heat suction/injection. The governing equations for momentum, shear stress and energy are modelled in the form of partial differential equations along with ramped wall temperature and ramped wall velocity boundary conditions. Laplace transformation is applied to convert principal partial differential equations to ordinary differential equations first and, later, complex multivalued functions of Laplace parameter are handled with numerical inversion to obtain the solutions in real time domain. Expression for Nusselt number is also obtained to clearly examine the difference in rate of heat transfer. A comparison for isothermal wall condition and ramped wall condition is also made to analyze the difference in both profiles. A graphical study is conducted to analyze how the fluid profiles are significantly affected by several pertinent parameters. Rate of heat transfer increases with increasing volume fraction of nanoparticle while shear stress reduces with elevation in retardation time. Moreover, flow gets accelerated with increase in Grashof number and Porosity parameter. For every parameter, a comparison between solutions of SWCNTs and MWCNTs is also presented.