Effects of surface roughness on mixed convective nanofluid flow past an exponentially stretching permeable surface

A numerical study is carried out to display the effects of surface roughness on mixed convective nanofluid flow along an exponentially stretching surface in presence of suction/injection. The dimensional coupled nonlinear partial differential equations are transformed into dimensionless form by using suitable non-similar transformations. The resulting equations are solved by utilizing the Quasilinearization technique as well as the implicit finite difference scheme. The influence of several non-dimensional parameters on various profiles and gradients is examined. The results are presented graphically, which are analyzed to depict the effects of various physical parameters, for example, Brownian diffusion parameter Nb, thermophoresis parameter Nt, suction/blowing parameter A and Lewis number Le. In order to analyse the influence of surface roughness on mixed convective nanofluid flow, the major part of this research paper is devoted to investigate the effects of the small parameter α and frequency parameter n over the gradients defined at the wall. The results reveal that an increase in the values of Nb and Nt, enhances the velocity and temperature of the fluid. The increasing value of suction parameter (A > 0) reduces the velocity of the fluid. Further, the increasing values of Nb and Le decrease the nanoparticle volume fraction profile. The sinusoidal variations are observed in the skin-friction coefficient, Nusselt number as well as the nanoparticle Sherwood number. Moreover, with the addition of nanoparticles, the magnitude of the skin-friction coefficient increases, while the magnitude of heat transfer rate decreases, significantly.