Significance of Variable Thermal Conductivity and Diffusivity on Nonsimilar Magneto-Thermo Convective Flow of a Micropolar Fluid on Stretching and Shrinking Surfaces

This paper investigates the magnetohydrodynamic (MHD) heat and mass transfer characteristics of an electrically conducting micropolar fluid over a vertical stretching and shrinking sheets in a porous medium, accounting for variable thermal conductivity and mass diffusivity. The Runge-Kutta-Fehlberg method, combined with the shooting technique, is used to solve the non-similar governing equations and analyzed the effects of important physical parameters. The Runge-Kutta-Fehlberg (RKF) method is a fourth-fifth order method that offers high accuracy and adaptive step sizing, making it well-suited for the non-linear differential equations governing the system. The RKF method iteratively adjusts the guess initial values until the solution meets the boundary conditions at infinity, which is crucial for accurate modeling in this type of flow. The novelty of this work lies in its detailed exploration of micropolar fluid behavior over stretching and shrinking sheets within a porous medium, incorporating the Darcy parameter, buoyancy effects, and variable thermal and mass diffusion properties. This study analyzes the combined influence of these parameters on microrotation, temperature, and concentration distributions on stretching and shrinking surfaces under radiative and porous conditions, which provides valuable implications for optimizing processes in industries like filtration, enhanced oil recovery, and thermal management. Results show that increasing the Prandtl number decreases the temperature distribution. The study also indicates that microrotation profiles decrease with buoyancy ratio parameter increase.Additionally, velocity and microrotation increase with the distance parameter ξ, while temperature and concentration profiles decrease with for both stretching and shrinking sheets. Furthermore, it is found that the Nusselt number increases by 62.66% when the Prandtl number is raised from 3 to 7, but only by 21.77% for an increase from 7 to 10, showing that the rate of increase in the Nusselt number diminishes as the Prandtl number rises.