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This paper investigates entropy generation rate in a temperature-dependent variable viscosity unsteady nanofluid flow past a convectively heated impulsively moving permeable cylindrical surface. The governing equations based on the modified Stokes first problem assumption are obtained and transformed using appropriate similarity variables into nonlinear ordinary differential equations. The numerical shooting method together with the Runge-Kutta Fehlberg integration scheme are employed to effectively solve the problem. The effects of related parameters on the nanofluid velocity, temperature, skin friction, Nusselt number, entropy generation rate and Bejan number are displayed graphically and quantitatively explained. It is found that an upsurge in nanoparticles volume fraction enhances the skin friction, Nusselt number, entropy production rate and the Bejan number. [ABSTRACT FROM AUTHOR]

The flow of ferronanofluid due to a rotating disk finds its significant place in biomedical sciences, pharmaceuticals, electronics, aerodynamics etc. Entropy generation appears in the systems/processes where its minimization is needed because it prohibits the decay of available energy which in turn boosts the efficiency of the associated thermal systems where it matters the most. In view of these added advantages, the flow and heat transfer behavior of ferronanofluid subject to slip, suction, electromagnetic field, Darcy–Forchheimer effect, and viscous dissipation, Ohmic heating and thermal radiation has been explored within this research. In addition, the role of entropy minimization associated with the flow concern has been analyzed. The apposite governing equations are numerically treated via shooting method. The important outcome of the study include infusion of more porous matrix develops controlled rotating flow due to both deformed disks. Rise in slip parameter augments flow velocity for stretched RD while that shows the adverse effect for shrunk RD. Controlled rate of heat transportation due to enhanced convective heating is significant for shrunk RD than that of stretched RD. Further, low Prandtl fluids, low molecular heat conduction and liquid friction yield entropy minimization thereby leading to uplift efficiency of thermal systems. [ABSTRACT FROM AUTHOR]

We consider heat and mass transfer analysis of magnetohydrodynamic (MHD) Carreau fluid flow along a stretching sheet in a permeable medium with impacts of melting condition, heat generation, double diffusion, and variable thermal conductivity. The novelty of the present work is to study the effects of melting heat transfer and heat generation on MHD flow of Carreau fluid along a stretched sheet in a porous medium with influence of Dufour and Soret effects, and variable thermal conductivity. Similarity transformations procedure is used which transform the partial differential equations (PDEs) of fluid flow model into nonlinear dimensionless ordinary differential equations (ODEs). We obtained numerical solutions of ODEs and the effects of assorted governing parameters are investigated. The results showed that boosting melting parameter increases velocity and concentration fields and reduces temperature profile. Enhancing heat source parameter increases temperature profile, concentration profile observing decline for modified Dufour parameter, Schmidt number, and Soret number, and velocity of the fluid decline for magnetic and porosity parameters. Impact of governing parameters on physical quantities comprising Nusselt number, skin friction, and Sherwood number is evaluated numerically. The accuracy of our results are established in comparison with previous research for skin friction coefficient and Nusselt number. [ABSTRACT FROM AUTHOR]

This work presents a theoretical numerical study of the bioconvection flow of Prandtl–Eyring nanofluid through a stretching cylinder with gyrotactic microorganisms. The mathematical model developed also incorporated the inclined magnetic field and heat generation effects. Further, stratification conditions are considered at the boundary of the stretched cylinder. The described flow problem conducting coupled high‐order partial differential equations (PDEs) is first reduced to the nonlinear system of ordinary differential equations (ODEs) by introducing suitable mathematical transformations. The resulting highly nonlinear flow equations are treated numerically by applying the shooting method. A comparison of the adapted method with previously reported data is also made to validate the presented results. The comparisons are in excellent agreement. The individual effect of controlling flow parameters/numbers on the flow profiles and physical quantities of engineering interest are represented graphically with physical descriptions. The significant results of the present analysis revealed that a rise in bioconvection Rayleigh number, thermal Grashof number, and angle of inclination boosts the velocity profile. The study shows that thermal stratification, mass stratification, and motile density stratification parameters diminish the temperature, concentration, and microorganism profiles, respectively. The nondimensional Sherwood number is decelerated significantly by thermophoresis and mass stratification parameters. [ABSTRACT FROM AUTHOR]

Mounting temperatures in electronic devices during operation may damage sensitive internal components if too much thermal energy accumulates inside the system. The advent of an innovative ultrahigh-performance thermal management technology known as nanofluid has provided a veritable platform to improve the system performance and reliability by removing the high heat flux generated in the engineering and industrial devices. This paper examines the combined effects of Darcy–Forchheimer porous medium-resistant heating and viscous dissipation on stagnation point flow of a Casson nanofluid (CoF e 2 O 4 - H 2 O and Ti O 2 - H 2 O) towards a convectively heated slippery stretching/shrinking cylindrical surface in a porous medium. The governing nonlinear model equations are obtained, analysed, and tackled numerically via the shooting technique with the Runge–Kutta–Fehlberg integration scheme. A unique solution is obtained when the surface is stretching. For shrinking cylindrical surface, the model exhibits nonunique dual solutions for a defined range of parameter values, and a temporal stability analysis is conducted to ascertain the stable and physically achievable solution. The effects of emerging thermophysical parameters on the overall flow structure and thermal management such as velocity and temperature profiles, skin friction, and Nusselt number are quantitatively discussed through graphs and in tabular form. It is found that the thermal performance heat transfer enhancement capability of Ti O 2 - H 2 O is higher than that of CoF e 2 O 4 - H 2 O. Moreover, the nanofluid thermal performance is enhanced with nanoparticles volume fraction, Casson nanofluid parameter, and Biot number but lessened with porous medium permeability. [ABSTRACT FROM AUTHOR]