Numerical simulation for thin-film flow of newtonian and casson hybrid nanofluid with heat transfer

Abstract

Nanofluid is one of the technologies used to improve heat transfer system. A class of nanofluid called hybrid nanofluid has been introduced recently. Hybrid nanofluid can upgrade thermal properties and consequently exhibit good heat transfer performance compared to nanofluid and conventional fluid. Besides that, the hybrid nanofluid has also manifested exquisite properties such as better chemical and mechanical inertness, greater thermal and electrical conductivity, and lower cost. In view of this, the problem of boundary layer flow of hybrid nanofluid embedded by the thin-film for viscous and Casson fluid past an unsteady porous stretching sheet is investigated in this thesis. Thin-film flow on a stretching sheet has a significant effect on heat transfer analysis. Such applications are used in many industrial operations including wire and fiber coating, metal and polymer extrusion, transpiration cooling, and optical industry such as production of smart contact lenses. This study begins with the derivation of the governing equation for the thin-film fluid flows and heat transfer based on the conservation law of mass, momentum, and energy. The modified Tiwari and Das model is applied to describe the properties of the hybrid nanofluid. Then, the developed nonlinear governing partial differential equations that are subjected to the appropriate boundary conditions are transformed into the nonlinear ordinary differential equations (ODEs) using the similarity transformation technique. The resulting nonlinear systems of the ODEs are then solved using the Keller box method. The unknown constant, thin-film thickness is obtained by the homotopy analysis method. The numerical results of surface shear stress and heat transfer coefficient as well as the velocity and temperature distributions for the pertinent parameters which are unsteadiness, nanoparticles volume fraction, Casson parameter, and intensity of suction and injection parameters are displayed graphically and in tabular forms. For both fluids, it is found that the thickness of thin-film is reduced due to increasing values of unsteadiness, nanoparticles volume fraction, Casson parameter, and intensity of injection. Numerical results depict that the presence of hybrid nanoparticles in both fluids not only enhanced the temperature distribution but it also reduced the velocity distribution, shear stress, and heat transfer coefficient. A similar pattern is revealed at the increment of Casson parameter. The unsteadiness parameter tends to upgrade the velocity and temperature distributions as well as the local skin friction. Incrementation of the velocity, temperature and shear stress in all fluids have been noticed along with the enhancement of injection parameter. Interestingly, suction fluid has changed the thickness of the thin-film that tends to be dense and helps to escalate heat transfer performance of the hybrid nanofluid.