## 1 Introduction
It can be seen from the available literature that limited or no attention has been given to the slip wall condition and the effects of variable thermophysical properties on the flow and heat transfer characteristics of nanofluids. Wall slip has far-reaching implications for many branches of science, engineering and industry. These include rheometric measurements, material processing and fluid transportation [27; 28]. Moreover, many processes in engineering occur at high temperature, and it is well known that the thermophysical properties of fluids may change with temperature and become important for the design of reliable equipment, nuclear plants, gas turbines and various propulsion devices or aircraft, missiles, satellites and space vehicles. On the basis of these applications, [PERSON] et al. [29] studied the flow and heat transfer of carbon nanotubes (CNTs) subjected to Navier slip and uniform heat flux boundary conditions. [PERSON] et al. [30] extended the idea and studied the effects of velocity slip and temperature jump on MHD flow and heat transfer of nanofluids over a porous shrinking sheet. Moreover, [PERSON] et al. [31] presented an investigation for the flow and radiation heat transfer of a nanofluid over a porous sheet with velocity slip and temperature jump in a porous medium. [PERSON] et al. [32] analyzed numerically the g-Jittermixed convective unsteady slip flow of nanofluids past a permeable linear porous sheet embedded in a Darcian porous media with variable viscosity. [PERSON] et al. [33] observed the effects of partial slip boundary conditions on the flow and heat transfer of nanofluids. [PERSON] et al. [34] carried out an analysis to investigate the influence of variable thermal conductivity and partial velocity slip on the hydromagnetic two-dimensional boundary layer flow of nanofluids over a porous sheet with a convective boundary condition. [PERSON] et al. [35] carried out a study on the effects of variable thermal conductivity and viscosity on the natural convective heat transfer of nanofluids over a vertical plate. Comprehensive studies and lists of important references on the wall slip condition and variable thermophysical properties of nanofluids are presented in [36; 37; 38; 39; 40; 41]. In the present work, a mathematical model is presented to study the effects of partial slip, variable viscosity and variable thermal conductivity on steady boundary layer flow of a nanofluid over a porous sheet in a Darcy-type porous medium. The wall slip conditions are employed in terms of shear stress, with viscosity and thermal conductivity as linear functions of temperature. Similarity solutions are obtained, and the reduced system of ordinary differential equations is solved numerically using the shooting method. The numerical results obtained for the velocity and temperature profiles are influenced appreciably by the presence of variable viscosity, variable thermal conductivity, porous medium, velocity and temperature slip and suction/injection parameters. The effects of various parameters on velocity and temperature profiles, as well as skin friction and the rate of heat transfer are presented and discussed through graphs and tables.