AXISYMMETRIC MHD BIOCONVECTIVE FLOW OF THIRD-GRADE CNT-BASED NANOFLUID WITH GYROTACTIC MICROORGANISMS OVER A STRETCHING CYLINDER UNDER VARIABLE THERMAL CONDITIONS

Abstract

The axisymmetric magnetohydrodynamic bioconvective flow of a third-grade carbon nanotube (CNT)-based nanofluid containing gyrotactic motile microorganisms traveling over a stretched cylindrical surface under variable thermal conditions is investigated in this work. The unified treatment of five concurrent physical effects — gyrotactic bioconvection, externally applied magnetic fields, CNT-based thermal enhancement, non-Newtonian third-grade rheological behavior, and convectively varying heat transfer at the boundary — incorporated in a single cohesive mathematical model is what distinguishes this work. A more physically accurate representation of transport processes relevant to advanced thermal engineering and biological applications is provided by such a combined approach. The controlling system of linked nonlinear partial differential equations, accounting for conservation of momentum, energy, nanoparticle concentration, and microbe density, is cast into a set of nonlinear ordinary differential equations via an appropriate similarity variable approach. The ensuing boundary value problem is tackled semi-analytically utilizing the Homotopy Analysis Method (HAM). Convergence is ensured by carefully calibrating the auxiliary convergence-control parameter. The current formulation's accuracy is verified using data already published in the open literature. In areas where the coupled transport of heat, species, and microorganisms is of engineering significance — such as magnetically regulated cooling devices, biomedical transport mechanisms, microbially enhanced nanofluid systems, and nano-engineered thermal management platforms — the physical implications are presented through parametric graphs and tabulated data.