Rotating-Disk Study Links Nanofluid Rheology to Entropy Generation

A new numerical study examines how non-Newtonian rheology shapes thermodynamic irreversibility in a magnetohydrodynamic (MHD) Eyring–Powell tri-hybrid nanofluid flowing over a rotating disk. The work, published open access in Discover Applied Sciences, addresses a gap the authors identify in the literature: while tri-hybrid nanofluids are known to improve thermal performance, the influence of non-Newtonian fluid behavior on entropy generation in rotating-disk configurations—particularly when motile microorganisms are present—has remained insufficiently explored.

The modeled fluid contains three types of nanoparticles—zirconium dioxide (ZrO2), multi-walled carbon nanotubes (MWCNT), and magnetite (Fe3O4)—dispersed in a mixture of ethylene glycol and water. The single-phase mathematical formulation incorporates nonlinear thermal radiation, viscous dissipation, and Joule heating to capture key thermal and irreversible effects, alongside magnetic-field, porous-medium, and bioconvection influences. Through an appropriate similarity transformation, the coupled governing partial differential equations were converted into a system of nonlinear ordinary differential equations and solved numerically with the fourth-order Runge–Kutta shooting technique.

The central finding concerns the two Eyring–Powell fluid parameters, which the study treats individually and which produce contrasting thermodynamic responses. Increasing the parameter λ1* promotes shear-thinning behavior and decreases entropy generation, whereas increasing λ2* enhances resistance to deformation and increases entropy generation. In other words, the same rheological framework can either suppress or amplify thermodynamic losses depending on which of its two parameters is varied.

The analysis also quantifies how viscous dissipation reshapes the balance of irreversibilities. Raising the Brinkman number from 1.0 to 3.0 intensifies irreversibility while lowering the Bejan number, indicating a greater contribution from viscous dissipation relative to heat-transfer irreversibility. On the bioconvective side, a threefold increase in the bioconvection Lewis number reduces the microorganism density number, tying the transport of motile microorganisms to the dimensionless groups governing the flow.

Perhaps the most striking contrast in the results is between thermodynamic and surface transport behavior. The surface skin-friction coefficient changes with the governing parameters, while the heat and microorganism transfer rates vary by less. The authors conclude that the rheological characteristics exert a considerably stronger influence on the entropy-generation mechanism than on the corresponding surface transport rates—a distinction with practical weight, since engineering applications such as rotating machinery, thermal management systems, and bio-microfluidic technologies require working fluids that deliver enhanced heat transport while keeping thermodynamic losses under control.

Because the study is a single-phase numerical model solved by similarity transformation, its findings are model-based predictions for the specified ZrO2–MWCNT–Fe3O4 nanofluid in an ethylene glycol–water base rather than direct experimental measurements. Even so, the results map out how magnetic fields, porous media, thermal radiation, Joule heating, and the two Eyring–Powell parameters jointly steer hydrodynamic, thermal, bioconvective, and entropy-generation characteristics in a rotating-disk geometry, offering a quantitative baseline for future work on loss-controlled nanofluid thermal design.

Subject of Research: Numerical analysis of entropy generation and heat transfer in MHD Eyring–Powell tri-hybrid nanofluid flow over a rotating disk

Article Title: Thermodynamic irreversibility and heat transfer characteristics of MHD Eyring–Powell tri-hybrid nanofluid flow over a rotating disk

Article References: Divya, A., Attallah, A. N., Jawad, M., & Eressa, L. A. (2026). Thermodynamic irreversibility and heat transfer characteristics of MHD Eyring–Powell tri-hybrid nanofluid flow over a rotating disk. Discover Applied Sciences. https://doi.org/10.1007/s42452-026-09747-y

Image Credits: AI Generated

DOI: 10.1007/s42452-026-09747-y

Keywords: tri-hybrid nanofluid, Eyring–Powell fluid, entropy generation, rotating disk, magnetohydrodynamics, bioconvection, thermal radiation, viscous dissipation, Joule heating, Brinkman number, Bejan number, heat transfer