Impact of an Inclined Magnetic Field on Thermo-concentration Boundary Layers in Unsteady Micropolar Magnetohydrodynamic Flow over a Nonlinear Stretching Sheet

Abstract

This work investigates the influence of an inclined magnetic field on thermo-concentration boundary layers in a micropolar magnetohydrodynamic (MHD) fluid flow over a nonlinear stretching surface. The magnetic field is applied at an inclination angle, altering the Lorentz force and hence affecting flow, heat, and mass transfer characteristics. Similarity transformations reduce the governing partial differential equations to ordinary differential form, which are further converted to a set of first-order ordinary differential equations and solved numerically using a collocation method in MATLAB. The results, which describe the impact of varying the angle of inclination of the magnetic field on the fluid velocity, angular velocity, temperature, concentration, skin friction, Nusselt number, and Sherwood number of the micropolar fluid, are presented in graphical and tabular form. They show that a 62.5% increase in the angle of inclination \(\alpha\) , increases the fluid velocity by 17.1% and temperature profile by 8.4% while the particle’s angular velocity and concentration decreases by 13.4% and 7.1% respectively and that a 29.2 % rise in the unsteadiness parameter lowers the fluid velocity by 3.3% and improves the angular velocity and temperature by 5.1% and 16.7% respectively. Further, the skin friction coefficient and Nusselt number increase with an increase in the angle of the inclination but Sherwood number decreases. For a higher unsteadiness parameter, the Nusselt number and Sherwood number increases but the skin friction decreases. The findings have significant implications for the design and control of MHD-based thermal systems where the orientation of the magnetic field and time dependent flow behavior plays a crucial control role for optimum performance. The results are consistent with existing literature on magnetic field orientation in unsteady fluid flow systems.