MHD hybrid nanofluid flow via varying porous space amid two stretchable rotating disks: A numerical approach

This study investigates the thermal performance enhancement achievable through the utilization of hybrid nanofluids (HNF) in variable porous media subjected to Magnetohydrodynamic (MHD) effects in a Casson fluid with two stretchable rotating disks. In the present study, the titanium dioxide ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi>Ti</mml:mi> <mml:msub> <mml:mrow> <mml:mi>O</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) and silver ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi>Ag</mml:mi> </mml:mrow> </mml:math> ) nanoparticles are suspended in water, which served as the base fluid. The governing equations are derived using similarity transformations and solved numerically using the bvp4c method achieving convergence with an accuracy tolerance of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . The study explores the influence of variable porosity parameter, stretching parameters, Lorentz force, Casson parameter and Biot’s number on velocity, pressure, and temperature distributions. The findings reveal that axial velocity of the hybrid nanofluid increases with lower disk stretching and Casson parameters, while temperature declines with an increase in the variable porosity factor. The study also highlights that radial velocity variations depend significantly on disk stretching parameters, with opposing trends observed between the lower and upper disks. Enhanced thermal profiles are noted with increasing Biot numbers, whereas magnetic effects suppress tangential velocity. Moreover, the results reveal that hybrid nanofluids significantly enhance heat transfer rates compared to traditional nanofluids, with up to a 23% improvement observed for specific parameter settings. This work highlights the practical applicability of hybrid nanofluids in thermal management systems, such as cooling technologies in aerospace and energy systems. The high thermal conductivity of the Ag-TiO 2 hybrid nanofluid makes it well-suited for cooling in microelectronic devices, where efficient heat dissipation is critical. Enhanced heat transfer properties are advantageous in solar collectors and geothermal systems, where maximizing energy efficiency through effective heat transport is essential. The model’s improved flow and thermal behaviors could contribute to efficient engine cooling, lubricant systems, and fuel cell performance, especially under high-performance and variable porosity conditions in aerospace and automobile industries.