## 2 Nanofluids: Techniques and Applications  
The effect of thermal radiation on the thin film nanofluid flow of a Williamson fluid over an unsteady stretching surface with variable fluid properties is investigated in [1]. Special attention has been given to the variable fluid properties. Analytical solutions of nonlinear governing equations are achieved by means of homotopy analysis method. Experimental values of the Prandtl number have been used to produce the results for the Williamson nanofluid, whereas the accuracy of the HAM results has been verified via numerical solutions. The effects of non-dimensional physical parameters--such as thermal conductivity, Schmidt number, Williamson parameter, Brinkman number, radiation parameter, and Prandtl number--have been thoroughly demonstrated and discussed. A comparison is also made for the validation of obtained results. In the paper \"On Squeezed Flow of Jeffrey Nanofluid between Two Parallel Disks\", [PERSON] et al. [2] presented the magnetohydrodynamic (MHD) squeezing flow of Jeffrey nanofluid between two parallel disks. Constitutive relations of Jeffrey fluid are employed in the problem development. Heat and mass transfer aspects are examined in the presence of thermophoresis and Brownian motion. [PERSON] fluid subject to time dependent applied magnetic field is conducted. Suitable variables lead to a strong nonlinear system. The resulting systems are computed via a homotopic approach. The behaviors of several pertinent parameters are analyzed through graphs and numerical data. Skin friction coefficient and heat and mass transfer rates are numerically examined. They found that the larger values of Deborah numbers correspond to lower temperature and concentration profiles. Both temperature and concentration profiles are higher for larger values of thermophoresis parameter. The present analysis reduces to a Newtonian nanofluid flow situation as a limiting case of this model. It is well known that the best way of convective heat transfer is the flow of nanofluids through a porous medium. In this regard, a mathematical model is presented in [3] to study the effects of variable viscosity, thermal conductivity and slip conditions on the steady flow and heat transfer of nanofluids over a porous plate embedded in a Darcy-type porous medium. The nanofluid viscosity and thermal conductivity are assumed to be linear functions of temperature, and the wall slip conditions are employed in terms of shear stress. The similarity transformation technique is used to reduce the governing system of partial differential equations to a system of nonlinear ordinary differential equations. The resulting system of ODEs is then solved numerically using the shooting technique. The numerical values obtained for the velocity and temperature profiles, skin friction coefficient, and Nusselt number are presented and discussed through graphs and tables. It is shown that the increase in the permeability of the porous medium, the viscosity of the nanofluid, and the velocity slip parameter decrease the momentum and thermal boundary layer thickness and eventually increase the rate of heat transfer. Moreover, the analysis can be extended to include the results for different water-based nanofluids, and a comparison can be generated on the heat transfer characteristics of different nanofluids. Clearly, there is an opportunity to consider/extend this problem with non-Newtonian nanofluid models and to perform experimental work on these systems. The studies of classical nanofluids are restricted to models described by partial differential equations of integer order, and the memory effects are ignored. Fractional nanofluids, modeled by differential equations with Caputo time derivatives, are able to describe the influence of memory on the nanofluid behavior.