Thermally stratified flow of hybrid nanofluids with radiative heat transport and slip mechanism: multiple solutions

Abstract

Research on flow and heat transfer of hybrid nanofluids has gained great significance due to their efficient heat transfer capabilities. In fact, hybrid nanofluids are a novel type of fluid designed to enhance heat transfer rate and have a wide range of engineering and industrial applications. Motivated by this evolution, a theoretical analysis is performed to explore the flow and heat transport characteristics of Cu/Al2O3 hybrid nanofluids driven by a stretching/shrinking geometry. Further, this work focuses on the physical impacts of thermal stratification as well as thermal radiation during hybrid nanofluid flow in the presence of a velocity slip mechanism. The mathematical modelling incorporates the basic conservation laws and Boussinesq approximations. This formulation gives a system of governing partial differential equations which are later reduced into ordinary differential equations via dimensionless variables. An efficient numerical solver, known as bvp4c in MATLAB, is utilized to acquire multiple (upper and lower) numerical solutions in the case of shrinking flow. The computed results are presented in the form of flow and temperature fields. The most significant findings acquired from the current study suggest that multiple solutions exist only in the case of a shrinking surface until a critical/turning point. Moreover, solutions are unavailable beyond this turning point, indicating flow separation. It is found that the fluid temperature has been impressively enhanced by a higher nanoparticle volume fraction for both solutions. On the other hand, the outcomes disclose that the wall shear stress is reduced with higher magnetic field in the case of the second solution. The simulation outcomes are in excellent agreement with earlier research, with a relative error of less than 1%.