Investigation of Magnetized Hybrid Nanofluid Flow Adjacent to a Shrinking Cylinder Considering Magnetic Dipole Effect

This study explores the micropolar ferrofluid flow of a hybrid base fluid (a mixture of ethyleneglycol (C_2 H_6 O_2) and water (H_2 O) in a proportion of 2:3) carrying 〖Fe〗_3 O_4 nanoparticles around a shrinking cylinder. The flow is controlled by quadratic radiative and non-linear buoyancy effects, with the additional influence of a magnetic dipole. Relevant similarity transformations are employed to derive the dimensionless non-linear ODEs from the governing equations of buoyancy driven boundary layer flow, which are then solved with the aid of shooting method. Comparison table shows excellent agreement with previously printed literature. The results reveal that the nonlinear thermal radiation parameter increases the Nusselt numbber by up to 34%. The magnetic dipole parameter enhances it by nearly 15-20%. Micropolar effects significantly intensify microrotation, with an increase of 31% observed for higher coupling numbers. The hybrid ferrofluid shows superior thermal performance compared to mono nanofluid, with a 19% enhancement in the Nusselt number. Additionally, through the application of Response Surface Methodology, the highest average heat transport (17.9474) is attained with the following parameter settings: maximum radiation parameter, minimum thermal slip parameter, and minimum stretching/shrinking parameter. This optimization is confirmed through residual and sensitivity analysis using quadratic fitting. Notably, the sensitivity of the average Nusselt number to the radiation parameter consistently shows a positive trend.