Free convective flow of Casson hybrid nanofluid around a horizontal circular cylinder with thermal radiation using differential transformation method

Purpose The flow of Casson fluid around a circular cylinder with a lower stagnation point has many real-world usages, such as cooling of electronic devices, movement of polymer solution in industrial processes and the circulation of blood through arteries. The main objective of this work is to develop a mathematical model for hybrid Casson nanofluid flow around a horizontal cylinder with a lower stagnation point. Furthermore, the momentum equation is incorporated by the external forces, i.e. magnetic field and free convection. Moreover, the energy equation is incorporated by Ohmic heating and thermal radiation. Design/methodology/approach The semi-analytical method named as DTM, “Differential transformation method,” is employed to obtain the solution of the nonlinear coupled ordinary differential equations. The advantage of DTM over other numerical techniques is that it doesn’t need any linearization, discretization or perturbation for solving the differential equations. The impact of various parameters, such as magnetic field, radiation, Darcy, Casson, Eckert number and Grashof number, on velocity and temperature profiles is examined. Findings The DTM results are validated with the works that have already been done. This study reports that an increase in the Eckert number from 0.1 to 0.5 results in the decline of heat transfer by 1.77%, while a maximum drop of 40.653% is recorded in heat transfer for the Grashof number increasing from 0.01 to 0.05. Originality/value The originality of this study lies in the development of a novel mathematical model that investigates the flow behavior of a non-Newtonian hybrid nanofluid containing two distinct types of nanoparticles. The model addresses buoyancy-driven flow around a horizontal cylinder embedded in a porous medium near the lower stagnation point. The findings of the study are particularly useful for evaluation heat transfer enhancement and cooling performance in the presence of radiative heat flux and magnetic fields – conditions usually encountered in the cooling of electronic equipment, heat exchangers, etc.