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Motivated by studying emerging nanofluid‐based magnetic fuel cells and hybrid direct absorber solar collectors, a numerical study is presented for buoyancy‐driven flow in a vertical enclosure containing a porous medium saturated with magnetized nanofluid flow under a transverse static magnetic field. The enclosure features adiabatic side walls and vertical heat slits, ensuring consistent cold temperatures on the lower and upper bounded walls. The side walls of the regime are insulated, and the hot slits are centrally located on these walls. The finite difference method (FDM) is applied to employ the transformed dimensionless vorticity–stream function (VSF) formulation of the transport equations. The impact of pertinent parameters on isotherm, streamline, iso‐concentration, and average Nusselt and Sherwood numbers are visualized with contour plots and graphs. Increasing Darcy number values tend to amplify the isotherm magnitudes. Higher Hartmann (magnetic) number values, on the other hand, lead to a reduction in local Nusselt number profiles but do not significantly modify the local Sherwood number. The porous medium permeability, as simulated via the Darcy number, has a strong impact on streamlines, thermal contours, and iso‐concentrations. A reduction in Darcy's number suppresses local Nusselt and Sherwood numbers, whereas an elevation in Rayleigh's number enhances them. Increasing the Buongiorno nanoscale Brownian motion parameter enhances local Nusselt and Sherwood numbers at both cold walls of the enclosure. The simulations provide a deeper insight into enclosure flows involving electrically conducting nanofluids in advanced processing systems for nanomaterials and hybrid fuel cells utilizing electromagnetic and liquid fuel technologies. [ABSTRACT FROM AUTHOR]

Medical engineering is increasingly deploying nanotechnology and bio-inspired designs in the 21st century. Motivated by studying the spin coating of bio-nanofluid materials, gyrotactic bioconvection nanofluid swirling coating flow from a spinning disk to an isotropic permeable medium is analysed. The balance equations for mass, momentum, thermal, concentration and microorganism species including blowing effects are transformed into ordinary differential equations and then the solutions are obtained numerically through MATLAB bvp4c quadrature. These solutions are further validated with Adomian decomposition method (ADM). Increasing radial momentum slip reduces the radial skin friction and increasing tangential slip suppresses the tangential skin friction. Nusselt number, nanoparticle Sherwood number and micro-organism density number gradient are, respectively, decreased with increment in thermal slip, nanoparticle mass slip and micro-organism slip factors. Combinations of bioconvection and nanofluids provide excellent advantages in designing anti-bacterial and resilient bio-coatings for many devices. [ABSTRACT FROM AUTHOR]

As a model for electroconductive nanomaterials processing, the article examines incompressible mixed convection nanofluid flow with convective heat transport from a stretching sheet under the impact of Joule heating and radiative heat flux. The transformed non-linear boundary value problem is solved with a robust Chebyshev collocation technique. Validation is conducted with earlier published results. Nanoparticle concentrations are suppressed with increasing chemical reaction parameter and the effect is strongest for copperwater nanofluid and weakest for TiO2 water nanofluid. Increasing Biot number boosts the temperatures for copper and Al2O3 but reduces it for TiO2 nanoparticles. Increasing heat generation boosts temperatures strongly for Al2O3 and TiO2 nanoparticles but weakly for copper nanoparticles. Greater thermophoresis parameter strongly boosts temperatures but suppresses nanoparticle concentrations. [ABSTRACT FROM AUTHOR]

A mathematical model is developed for viscous slip flow and heat transfer in water/Ethylene glycol‐based nanofluids containing metallic oxide nanoparticles, through a converging/diverging channel. We adopt the single‐phase Tiwari–Das model. The governing equations are transformed to a set of similarity differential equations with the help of similarity transformation, before being solved numerically using Maple 20. Validation of the velocity gradient and temperature solutions is achieved with the second‐order implicit finite difference Keller Box method. Further validation is included for the special case of no‐slip nanofluid flow in the absence of viscous heating. The effects of the parameters, namely velocity slip, thermal jump, channel apex angle, Eckert number, Prandtl number, Reynolds number, and nano‐particle volume fraction on velocity, temperature, skin friction, and heat transfer rate are investigated in detail. It is found that with increasing velocity slip, for water‐TiO2 and ethylene glycol‐TiO2 nanofluids, the channel bulk flow is decelerated whilst with greater solid (nanoparticle) volume and in the presence of momentum slip, the flow is also retarded. With the increasing semivertex angle, the channel flow is generally accelerated. An increase in divergent semiangle leads to decelerate the flow from the centerline for the core flow region, whereas near and at the channel wall, it results in a weak acceleration. Higher temperatures are achieved with greater thermal slip values, for both water‐TiO2 and ethylene glycol‐TiO2 nanofluids, whereas for greater nanoparticle volume fraction, temperatures are weakly decreased for water‐TiO2 whereas a more significant decrease is observed for ethylene glycol‐TiO2 nanofluid. With a greater diverging channel angle, a substantial decrease in temperatures is caused by greater Reynolds numbers, and the reverse effect is computed for the converging channel. The novelty of the current work is that it extends previous studies to include multiple slip effects and viscous heating (Eckert number effects), which are shown to exert a significant influence on heat and momentum transfer characteristics. The study is relevant to certain pharmaco‐dynamics devices (drug delivery), next‐generation 3D nanotechnological printers, and also nano‐cooling systems in energy engineering where laminar flows in diverging/converging channels arise [ABSTRACT FROM AUTHOR]

With emerging applications for smart and intelligent coating systems in energy, there has been increasing activity in researching magnetic nanomaterial coating flows. Surface tension features significantly in such regimes, and in the presence of heat transfer, Marangoni (thermocapillary) convection arises. Motivated by elaborating deeper the intrinsic transport phenomena in such systems, in this paper, a mathematical model is developed for steady radiative heat transfer and Marangoni magnetohydrodynamic flow of a Cu‐water nanofluid influencing a strong magnetic field through a porous disk. The semianalytical adomain decomposition method is employed to find the solution of flow governing equations, which are reduced into ordinary differential equation form via the Von Karman similarity transformation. Validation with a generalized differential quadrature algorithm is included. The response in dimensionless velocity, temperature, wall heat transfer rate and shear stress is investigated for various values of the control parameters. Temperature is reduced with increasing Marangoni parameter, whereas the flow is accelerated. With increasing permeability parameter, the temperatures are elevated. Increasing radiative flux boosts temperatures further from the disk surface. Increasing magnetic parameter strongly dampens the boundary layer flow and elevates the temperatures, also eliminating temperature oscillations at lower magnetic field strengths. [ABSTRACT FROM AUTHOR]

Increasingly sophisticated techniques are being developed for the manufacture of functional nanomaterials. A growing interest is also developing in magnetic nanofluid coatings which contain magnetite nanoparticles suspended in a base fluid and are responsive to external magnetic fields. These nanomaterials are "smart" and their synthesis features high-temperature environments in which radiative heat transfer is present. Diffusion processes in the extruded nanomaterial sheet also feature Soret and Dufour (cross) diffusion effects. Filtration media are also utilized to control the heat, mass and momentum characteristics of extruded nanomaterials and porous media impedance effects arise. Magnetite nanofluids have also been shown to exhibit hydrodynamic wall slip which can arise due to non-adherence of the nanofluid to the boundary. Motivated by the multi-physical nature of magnetic nanomaterial manufacturing transport phenomena, in this paper, we develop a mathematical model to analyze the collective influence of hydrodynamic slip, radiative heat flux and cross-diffusion effects on transport phenomena in ferric oxide ( Fe 3 O 4 -water) magnetic nanofluid flow from a nonlinear stretching porous sheet in porous media. Hydrodynamic slip is included. Porous media drag is simulated with the Darcy model. Viscous magnetohydrodynamic theory is used to simulate Lorentzian magnetic drag effects. The Rosseland diffusion flux model is employed for thermal radiative effects. A set of appropriate similarity transformation variables are deployed to convert the original partial differential boundary value problem into an ordinary differential boundary value problem. The numerical solution of the coupled, multi-degree, nonlinear problem is achieved with an efficient shooting technique in MATLAB symbolic software. The physical influences of Hartmann (magnetic) number, Prandtl number, Richardson number, Soret (thermo-diffusive) number, permeability parameter, concentration buoyancy ratio, radiation parameter, Dufour (diffuso-thermal) parameter, momentum slip parameter and Schmidt number on transport characteristics (e.g. velocity, nanoparticle concentration and temperature profiles) are investigated, visualized and presented graphically. Flow deceleration is induced with increasing Hartmann number and wall slip, whereas flow acceleration is generated with greater Richardson number and buoyancy ratio parameter. Temperatures are elevated with increasing Dufour number and radiative parameter. Concentration magnitudes are enhanced with Soret number, whereas they are depleted with greater Schmidt number. Validation of the MATLAB computations with special cases of the general model is included. Further validation with generalized differential quadrature (GDQ) is also included. [ABSTRACT FROM AUTHOR]

We analyse the steady convection boundary layer flow of a second order non- Newtonian fluid near a wedge structure embedded in a Darcy - Brinkman porous medium. The governing equations are formulated using a boundary layer theory, then transformed into pseudo-similarity equations and these equations are subsequently solved using the powerful Nakamura finite difference method. Solutions are produced for surface shear stress and local heat transfer at the wedge face. The effects of viscoelasticity coefficient, K, Reynolds number. Re, Prandtl number. Pr, and Darcy number, Da, are presented graphically and discussed. [ABSTRACT FROM AUTHOR]