Stability analysis and dual solutions of time-dependent stagnation-point heat transport of Casson nanofluid by using Tiwari–Das model

Abstract

Magnetohydrodynamic (MHD) time-dependent stagnation point flow and heat transfer characteristics of Casson base nanofluid over porous shrinking/stretching sheet with velocity slip and radiations effects is considered. The Tiwari–Das model is incorporated with silver (Ag), gold (Au), and iron (Fe) nanoparticles. The similarity variables are used to transfer the modeled partial differential equations into the system of ordinary differential equations. The shooting technique through Maple software is used to check the effects of different physical parameters used in equations and boundary conditions. The stability analysis at different values of the used parameters is performed due to existence of duality in the solutions. In the results, the second solution is found unstable while first one is physically reliable and stable. Numerically achieved findings of this problems show the skin friction coefficient is decreasing for and increasing for when the suction rate and nanoparticles volume-fraction are increased. The local Nusselt number is higher against the rising suction parameter and lower for the incremented nanoparticles volume fractions for both cases of Comparatively, the thermal conductivity and drag force of Au-nanoparticles is seen greater than Ag and Fe, while Fe greater than Ag in Casson nanofluid flow. The velocity profiles decrease with increase in nanoparticles volume fractions, Casson, suction and velocity slip parameters, while, an increase in unsteady parameter increases velocity profile. Moreover, radiation, nanoparticles volume fractions and magnetic parameters increase the temperature profiles.