<p>Trihybrid ferro-nanofluids, combining ternary magnetic nanoparticles with motile microorganisms in a porous environment, represent a frontier class of engineered fluids with significant relevance to biomedical microdevices, solar thermal collectors, and bioreactor engineering. This study numerically investigates the coupled effects of a magnetic dipole interaction, Cattaneo–Christov (CC) double diffusion, Darcy–Forchheimer porous resistance, activation energy, and bioconvection on the boundary layer flow of a Casson trihybrid ferro-nanofluid over a linearly elastic stretching surface. The working fluid is a water–ethylene glycol (WEG) mixture loaded with ternary ferromagnetic nanoparticles (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\hbox {Fe}_3\hbox {O}_4$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>Fe</mtext> <mn>3</mn> </msub> <msub> <mtext>O</mtext> <mn>4</mn> </msub> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\hbox {CoFe}_2\hbox {O}_4$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>CoFe</mtext> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>4</mn> </msub> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\hbox {MnFe}_2\hbox {O}_4$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>MnFe</mtext> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>4</mn> </msub> </mrow> </math></EquationSource> </InlineEquation>) and gyrotactic microorganisms, and convective boundary conditions are imposed for heat, mass, and microorganism transport. Thermal and solutal transport is governed by the CC heat and mass flux formulations, which introduce finite relaxation times and thereby capture non-Fourier conduction and non-Fickian diffusion. The governing coupled nonlinear partial differential equations are reduced to a system of ordinary differential equations via appropriate similarity transformations and solved numerically with MATLAB’s bvp4c collocation solver. The results reveal that ferrohydrodynamic interactions suppress fluid motion, elevate temperature, increase skin friction, and reduce heat transfer rates. Enhanced Forchheimer inertia further strengthens flow resistance and wall shear stress. Thermal relaxation improves surface heat transfer despite delaying heat flux propagation, whereas solutal relaxation reduces concentration levels and mass transfer rates. Increasing activation energy weakens reaction kinetics, leading to lower Sherwood numbers. Furthermore, larger Péclet numbers promote advective transport, reducing near-wall microorganism concentration and enhancing microbial density transport. The present framework offers a systematic numerical characterization of the interplay between ferrohydrodynamic, bioconvective, and non-Fourier transport mechanisms, providing a theoretical basis for future application-specific investigations in advanced thermal management and biomedical systems.</p>

Bioconvective trihybrid ferro-nanofluid flow in Darcy–Forchheimer porous media with Cattaneo–Christov double diffusion and magnetic dipole effects

期刊论文
发表日期：

2026年7月4日

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Asgar Ali,
Suvendu Maity,
Subhabrata Mondal,
Sanatan Das,
Soumen De

摘要

Trihybrid ferro-nanofluids, combining ternary magnetic nanoparticles with motile microorganisms in a porous environment, represent a frontier class of engineered fluids with significant relevance to biomedical microdevices, solar thermal collectors, and bioreactor engineering. This study numerically investigates the coupled effects of a magnetic dipole interaction, Cattaneo–Christov (CC) double diffusion, Darcy–Forchheimer porous resistance, activation energy, and bioconvection on the boundary layer flow of a Casson trihybrid ferro-nanofluid over a linearly elastic stretching surface. The working fluid is a water–ethylene glycol (WEG) mixture loaded with ternary ferromagnetic nanoparticles ( $\hbox {Fe}_3\hbox {O}_4$ ${Fe}_{3} O_{4}$ , $\hbox {CoFe}_2\hbox {O}_4$ ${CoFe}_{2} O_{4}$ , $\hbox {MnFe}_2\hbox {O}_4$ ${MnFe}_{2} O_{4}$ ) and gyrotactic microorganisms, and convective boundary conditions are imposed for heat, mass, and microorganism transport. Thermal and solutal transport is governed by the CC heat and mass flux formulations, which introduce finite relaxation times and thereby capture non-Fourier conduction and non-Fickian diffusion. The governing coupled nonlinear partial differential equations are reduced to a system of ordinary differential equations via appropriate similarity transformations and solved numerically with MATLAB’s bvp4c collocation solver. The results reveal that ferrohydrodynamic interactions suppress fluid motion, elevate temperature, increase skin friction, and reduce heat transfer rates. Enhanced Forchheimer inertia further strengthens flow resistance and wall shear stress. Thermal relaxation improves surface heat transfer despite delaying heat flux propagation, whereas solutal relaxation reduces concentration levels and mass transfer rates. Increasing activation energy weakens reaction kinetics, leading to lower Sherwood numbers. Furthermore, larger Péclet numbers promote advective transport, reducing near-wall microorganism concentration and enhancing microbial density transport. The present framework offers a systematic numerical characterization of the interplay between ferrohydrodynamic, bioconvective, and non-Fourier transport mechanisms, providing a theoretical basis for future application-specific investigations in advanced thermal management and biomedical systems.