Numerical simulations using finite-element scheme for the optimization of micropolar tri-hybrid nanofluids with periodic gravitational disturbance and heat source/sink effects

Abstract

Advancing heat transfer mechanisms in gravitationally varying environments is crucial for improving engineering applications in aerospace engineering, astrophysics, spacecraft, and satellites. Motivated by these applications, this study examines the influence of periodic variations in gravitational acceleration and externally applied magnetic fields on heat and momentum transfer over an inclined stretching sheet situated in an upper-atmosphere or microgravity regime. The thermophysical properties of glycerine, carbon nanotubes (CNTs), gold (Au), and aluminum oxide (Al 2 O 3 ) are incorporated to evaluate their contributions to enhancing thermal conductivity and heat transport performance. The transformed governing equations are numerically solved using the finite element method (FEM), with simulations executed in Wolfram Mathematica to assess the impact of key physical parameters. The results indicate that hybrid and ternary hybrid nanofluids substantially outperform mono nanofluids. Specifically, the ternary hybrid nanofluid yields up to a 31.6% increase in temperature distribution and a 27.4% rise in velocity magnitude relative to the base nanofluid. An increase in the micropolar material parameter enhances fluid motion, producing an 18.2% increase in velocity, while increasing the Hartmann number reduces the velocity by approximately 22.9%, confirming the expected magnetic damping effect. Additionally, both the skin-friction coefficient and the Nusselt number increase with higher gravity modulation amplitudes, showing up to a 24.7% rise in shear stress and a 29.3% improvement in heat transfer rate. Overall, the findings demonstrate the superior heat transport capability of ternary hybrid nanofluids under fluctuating gravity conditions, highlighting their potential for advanced thermal management in space and microgravity engineering applications.