Thermal transport enhancement in SWCNT/MWCNT hybrid nanofluids over a Riga plate: Effects of radiation, heat generation, and porous media

This study investigates the thermal energy transport of an SWCNT–MWCNT/propylene glycol hybrid nanofluid over a Riga plate, integrating the coupled effects of thermal radiation, internal heat generation, and variable porosity. The main novelty is the systematic reduction of the governing partial differential equations to nonlinear ordinary differential equations using scaling group transformations and the numerical solution of the latter using the finite difference method implemented in MATLAB. The physical quantities show that the fluid flow velocity is significantly reduced by the magnetic parameter and variable porosity because of increased resistive drag forces, while the modified Hartmann number is a mechanism that increases the fluid flow velocity by 15%–18%, by increasing the electromagnetic forces. The thermal performance of the hybrid nanofluids based on SWCNT is better than the MWCNT-based nanofluids, with a maximum of 20% improvement in the temperature fields for the same baseline states ( M = 0 . 5 , λ = 0 . 3 , ϕ 1 = ϕ 2 = 0 . 01 and B = 0 . 3 ). The enhanced ballistic phonon transport, the reduced Kapitza resistance at the interface and the optimized aspect ratio of the nanoparticles are the fundamental causes of this superior thermal performance. By itself, internal heat generation results in a critical 14% thermal rise, indicating its effectiveness in boosting thermal levels locally. The quantitative information presented provides basic guidelines for the design of predictable, highly efficient industrial thermal systems, electronic cooling devices, and novel heat exchangers.

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