Film thinning and heat transfer analysis of Casson hybrid-nanoliquid flow over an unsteady permeable stretching sheet in presence of magnetic field

Most of the studies on thin nanoliquid film flow over a stretching surface are primarily confined to only one type of metallic/nonmetallic nanoparticles suspended on the Newtonian base liquid. This article, on the other hand, investigates the development of thin non-Newtonian Casson hybrid nanolquid (CHNL) film over an unsteady porous stretching sheet in presence of transverse magnetic field. Here, more than one type of metallic/nonmetallic nanoparticles are suspended in the non-Newtonian Casson base liquid. Using the appropriate similarity transformations, the entire set of energy and momentum equations are transformed into a set of coupled non-linear partial differential equations. The singular perturbation technique and matched asymptotic method have been used to find analytical expressions for the temperature and velocity fields. Finally, the longtime film evolution equation is solved numerically by Runge–Kutta method of order four. The results shows that the film height for CHNL enhances for increasing values of nanoparticles volume fractions, Casson parameter, porosity parameter and Hartmann number respectively. It is seen that thermocapillary parameter accelerates film thinning rate when the sheet is cooling along the stretching direction whereas reverse phenomenon occurs for heating. It is noticed that the temperature attends larger values for CHNL as compared to pure Casson liquid and this temperature increases for raising the nanoparticles volume fractions in case of CHNL. A curve within the CHNL film may be described which demarcates the heat transfer region into two sections. In one section, heat is transferred from CHNL film to the stretching surface whereas, on the other section, heat is transferred from stretching sheet to CHNL film.