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Significant cooling is an essential requirement in the field of aeronautical and bio-medical engineering, nuclear reactor system, solar collectors, and in development of electronic chips etc. Involving rotating conical geometries. In view of this, flow and heat transfer over conical geometries subject to different constraints of motion are highly needed. Implementation of magnetic field subject to flow pattern controls the fluid motion thereby imparting better cooling. Consideration of nanofluid instead of regular fluid yields prominent cooling of the associated surface. Such relevance has motivated the authors to work on magnetohydrodynamics and heat transfer investigation of water-EG (50:50) mixture based Al2O3 and Fe3O4 past heated and rotating down-pointing upright cone subject to impact of space and temperature varying non-uniform heat source or sink. Numerical solution of dimensionless governing equations is accomplished by implementing Runge-Kutta method. The findings indicate that swirl and axial velocities peter out with rise in magnetic parameter while both exhibit opposite impact in response to slip parameter. Temperature profiles upgrade due to amplification of space and temperature dependent parameters. Skin friction and heat transportation upsurge with growth of solid volume fraction of nanoparticle.

In fact, local thermal equilibrium (LTE) would be unsuitable when it comes to nuclear reactors, electronic equipment, space devices, geothermal engineering, and high-conductivity foams, due to prominent temperature discrepancy between the two constituents (solid and nanofluid) in porous material. Local thermal non-equilibrium (LTNE) situation may be considered in above real world applications. In view of above relevance, the effects of LTNE model on double-diffusive natural convection (DDNC) within a fluid-saturated porous container loaded with the TiO2-H2O nanofluid and emplacing four cooling and hot channels in Forchheimer-Brinkman-extended Darcy medium have been investigated in the present study. The momentum, heat and mass equations are solved by finite element method. Irreversibility in the two constituents (nanofluid and solid) of the porous structure has been analyzed. The significant outcomes are that fluid circulations enhance due to rise in porosity of the medium. Fluid friction entropy EnFF,T ameliorates significantly by 1514.16 % and 872.97 % with increase in Rayleigh number and porosity of the medium. It is clear that Nuloc,nf,Nuave,nf, Nuloc,s&Nuave,s enhance significantly with rise of buoyancy and thermal conductivity ratio, interstitial solid/fluid heat transfer coefficient.

Since performance of thermal systems may depend on fluids’ thermal conductivities being utilized as coolants, improvement of thermal efficiencies of fluids having micro-structures and involving ternary hybrid nanomaterials may be highly valued. In fact, microrotation of ternary hybrid nanofluids (THNFs) in oblique incinerator-shaped chamber may find applications in industrial processes involving polymeric solutions and lubricants where they help in reduction of drag forces and act as better cooling agent. In view of this, the present study carries out thermal and second law dissection of micropolar THNF within an oblique incinerator-shaped chamber heated from bottom emplacing a roundish heater under a fixed heat flux. The THNF comprises of Al2O3, CNT and graphene as nanoparticles. The study reveals that streamlines and isotherms undergo prominent change due to inclination of the chamber. When Raleigh number and diameter of heater amplify streamlines, microrotations, and entropy generation intensify while average Bejan number whittles down. Average heat transfer rate ameliorates by 4.54 % and 2.17 % when total volume fraction augments from 1.5 % to 3 % and 3 %–4.5 %, respectively. Heat transfer rate reduces by 1.23 %, 0.48 %, 3.33 %, 5.24 %, 2.07 %, and 1.66 % when inclination angle increases from 0° to 90° with inclination angle step 15°.

As witnessed worldwide, there has been rapid growth in research and the creation of energy storage devices such as supercapacitor electrodes that can store and deliver energy at a speedy rate, and provide high currents in a short duration. This article deals with a review on how supercapacitor (SC) electrode materials get developed from bio-waste like cooked chicken bone waste (CCBW), chicken egg shells, fish gills, fishbone waste, and biodegradable and non-biodegradable marine wastes such as plastics, mangroves, chitosans, and mussel shells, which provide economic benefit for the substantiality of supercapacitor technology. The synthesis and preparation involved in the study include one step activation and colloidal blending processes. The characterization of the as-prepared materials is carried out by implementing XRD, FESEM, EDS, FT-IR, TGA, TEM, and RAMAN spectroscopy. It is visualized that electrode materials possess high carbon content with porosity leading to a greater specific surface area, which is essential for high conductance SC electrodes. Researche on electrochemical analysis of prepared electrodes from such marine waste materials using CV, GCD, and EIS techniques has been analyzed.

Magnetohydrodynamic free convection liquid considering Hall along with ion-slip current has many engineering usages. In addition, boundary layer flow of power-law fluids due to a stretching plane possesses sundry applications in biological sciences, geophysics, and petroleum industries. Further, hybrid nanofluids are important due to their high heat transfer capability. In view of such relevance, the goal of this investigation is to analyze Hall along with ion-slip effects on thermo-fluidic flow of magnetic power-law hybrid nanofluid so as to accomplish effective cooling in the desired thermal systems. Present investigation’s novelty is adding hybrid nanostructure to power-law fluid flow influenced by Hall and ion-slip mechanism and implementation of modified Fourier’s law featured with velocity and temperature gradients. The key results are that fluid velocity amplifies with rise in ion-slip and Hall parameters. Modified Prandtl numbers and Hall parameter ameliorate heat transfer rate while ion-slip parameter diminishes it.

The study of natural convection and heat transfer in a trapezoidal cavity finds a wide range of technological applications including thermal energy storage systems, building ventilation/insulation, waste heat recovery, electronic device cooling, controlling PV panel temperature, energy conservation, exchangers, nuclear reactors, furnaces, glass production, food processing, and drying technologies. The purpose of the current study is to explore the entropy and natural convection of non-Newtonian nano-encapsulated phase change material (NEPCM) suspension in a saturated porous medium enshrouded in a trapezoid-shaped domain with three heated blocks fitted with the bottom surface. The novelty of the present work is the introduction of power-law (Ostwald-de Waele) model subject to NEPCM suspension in trapezoidal enclosure emplacing three heated fins at its bottom surface embedded in Brinkman-Forchheimer extended Darcy medium with variant porosity. The finite element method is implemented to solve the governing equations numerically. The important findings of the present study include streamlines, isotherms, velocities, and apparent viscosity enhance while entropy generation whittles down with rise in Darcy number. Entropy generation ameliorates by 519.16 % for low to high porosity of Brinkman-Forchheimer extended Darcy medium. The maximum apparent viscosity augments by 1441.24 % when power law index ameliorates.

The present work deals with thermal aspect and entropy of ternary hybrid nanofluid (Graphene, Al2O3, and MWCNT as nanoparticles and water as base fluid) inside an inclined domain considering heat generation/absorption. The domain possesses triangle-shaped corrugated walls with variable height and a semi-circular heater located on its bottom wall. Finite element method (FEM) is employed to acquire a well-defined solution of the non-dimensional governing equations along with the boundary conditions. The influence of the pertinent parameters along with their ranges (0.2≤b≤0.3), (105≤Ra≤106), (0o≤η≤90o), (−1≤Hs≤1) has been studied. Some striking outcomes of the present investigation are that streamlines and entropy generation (EnT) peter out while local Nusselt number (Nuloc) and average Bejan number (Beave) ameliorate with rise in dimensionless height of the corrugated wall (b). The absolute maximum values of vertical and horizontal velocities of ternary hybrid nanofluid enhance by 96.47 % and 29.5 %, respectively, when inclination angle (η) increases from 45o to 90o. It is visualized that Nusselt number is maximum subject to heat sink while it attains a minimum value in response to heat source. Because of triangle shaped corrugated walls and ternary hybrid nanofluid, the present problem contributes superior cooling in thermal systems featured with such complex geometry in industries.

The present study analyzes on the reviews carried out by the previous researchers on the entropy generation caused by the flow and heat transfer of several composite nanofluids subject to varieties of geometries under the influence of several constraints of motions. The composite nanofluids include binary hybrid nanofluids and ternary hybrid nanofluids involving disparate base fluids with different suitable nanoparticles. The geometries considered are deformed surfaces (stretched/shrunk sheets, cylinders, and disks), channels and cavities. Several numerical techniques such as Runge-Kutta method and finite element/difference/volume methods are implemented in the investigations. The major and significant outcome of the review analysis is the entropy comparison for different types of nanofluids. Growth of the volume percentage of nanoparticles at a fixed mass flow rate enhances entropy formation. When porosity strength increases, the irreversible entropy production caused by fluid friction results in increased thermal efficiency of certain systems than magnetic entropies. Compared to single nanofluids, hybrid nanofluids display the maximum entropy. With increasing Rayleigh numbers, the frictional and magnetic entropies in composite nanofluids ameliorate significantly than thermal entropy.

The present work may deal with the flow, heat transfer and entropy dissections of hydromagnetic buoyancy-driven nanoliquid inside a diamond-shaped container considering ⊥- shaped obstacle of varying configurations subject to heat/sink source and porous matrix. The importance of the above problem is due its potential utilizations in modern industries such as thermal extrusion systems, solar energy collectors, heat exchangers, microelectronic cooling, automobiles, building ventilation, bio-medicine etc. The equations governed may well be solved via finite element method. The present work's novelty would be the introduction of ⊥- shaped obstacle of varying configurations in a diamond shaped cavity embodying a porous matrix and analyzing the flow along with heat transfer aspects there in. The main findings are that alteration of flow nature from hydrodynamic to hydromagnetic whittles down streamlines and augments isotherms at given Rayleigh number in presence of source/sink subject to porous medium. Total entropy exhibits 3896 % enhancement and average Bejan number shows sharp 85.5 % diminution due to rise of Rayleigh number. The outcomes of the present study finds effective and persistent industrial cooling due to better stability of alumina nanoparticles in nanofluid involved in complex geometries like diamond shaped cavities which is the beyond of existing literature.

Natural convection heat transfer in a porous prismatic enclosure emplacing two movable hot baffles may well be executed in this research. The domain may be loaded with ternary hybrid nanofluid and the governing energy and Navier-Stokes equations might well be solved using finite element approach. The simulation is devised for a wide range of Darcy number, Rayleigh number, non-dimensional length between hot baffles. Examination of the influence of flow and thermal fields through isotherms, vertical and horizontal velocities, streamlines and Nusselt and Bejan numbers is carried out lucidly. Water + Carbon Nanotube (cylindrical)+ Al2O3(spherical)+ Graphene (platelet) is regarded as heat transfer medium within the enclosure. Results indicate that amplification of Darcy number upgrades vertical and horizontal velocities up to 88.51% and 83.77%, respectively, streamlines up to 88.12% as well as Nusselt numbers and isotherms effectively. Augmented Rayleigh number gives rise to intensification of isotherms, vertical and horizontal velocities, and streamlines while it exhibits reverse effect for average Bejan number. Moreover, rise of non-dimensional length between hot baffles from 0.4 to 0.6 leads to the encumbrance of maximum streamline, horizontal and vertical velocities by 11.32%, 8.6% & 5.12% respectively and lifts up average Bejan number by 24.17%.

In this analysis, the interfacial layer and shape effects has been inspected numerically for the Darcy Forchheimer electromagnetic flow of single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNTs) with base fluid (water) nanofluids. The influence of nonlinear thermal radiation and homogenous and heterogeneous chemical reactions are also taken into account. A revised Hamilton Crosser model is implemented for measuring interfacial layer and shape effects of carbon nanotubes-water nanofluid. The flow problem for examining the heat transfer features has been modeled in term of nonlinear equations by incorporating the Hamilton–Crosser model. The main objective for performing the current work is to analyze how the shapes of nanoparticles effect towards the flow of considered fluid with various thermal features. The entropy generation analysis is performed as novelty. The governing dimensionless equations are numerically solved by fourth order Runge–Kutta method computational shooting technique. The relevant parameter variations on axial, radial, tangential velocity, temperature, concentration, skin friction, Nusselt number, entropy generation rate and Bejan number are highlighted. The enhanced shape factor of nanoparticles contributes to accelerated flow along axial and radial directions while it yields decelerated flow along tangential direction of lower and upper disks. The augmented interfacial layer parameter enhances heat transportation from the surfaces of lower and upper disks.

In the present investigation, the magnetohydrodynamic Falkner-Skan flow of tangent hyperbolic nanofluids over a stretching/shrinking wedge with variable suction, internal heat generation/absorption and chemical reaction with activation energy have been scrutinized. Nanofluid model is composed of “Brownian motion’’ and “Thermophoresis’’. Transformed non-dimensional coupled non-linear equations are solved by adopting the fourth-order R-K method along with the shooting technique. A comprehensive analysis of nanofluid velocity, the relative temperature, and its concentration profiles has been addressed. The major outcomes of the current study include that augmentation in the Weissenberg parameter, Hartmann number along with suction impede fluid flow and the shrinkage of the related boundary layer while internal heating develops an ascending thermal boundary layer for static and moving (stretching/shrinking) wedge. An increment in reaction rate undermines the nanoparticle concentration while that of activation energy exhibits a reverse trend.

Background: Characterised with augmented heat transport and thermal efficiency, nanofluids are implementable in diversified applications include pharmaceutical industries, hybrid-powered machines, cooling of different appliances, refrigerator, microelectronic, heat exchanger etc. Taking such advantages into mind, physical aspects of entropy optimization and non-linear thermal radiation in Darchy–Forchheimer flow of copper–water nanofluid due to a rotating disk are examined. A new thermal conductivity model of nanofluids involving static and dynamic approach is considered. This model signifies hydrodynamic interaction among the Brownian motion induced fluid particles. The Cattaneo–Christov heat flux theory is taken into account. The second law of thermodynamics is the instrumental for the determination of total entropy generation rate. Methods: The system of nonlinear PDEs is converted into system of nonlinear ODEs through favorable transformations. Shooting technique has been applied prospectively to accomplish the desired numerical solution of the transformed equations. Results: The behavior of velocity (axial, transverse and tangential) and thermal fields influenced by varied physical parameters is impressed through graphs and numerical tables. Velocity field peters out due to rising porosity parameter as well as volume fraction while thermal field upgrades for higher Biot number and radiation parameter. Significant heat transfer rate is obtained for smaller estimation of radiation parameter. Entropy generation rate and Bejan number exhibit similar trend for radiation parameter and opposite fashion for Reynolds number. Conclusions: The diminishing velocity distribution for larger access of porous matrix while elevated temperature distribution for higher temperature parameter (due to nonlinear thermal radiation). Entropy minimization is accomplished for grater estimation of Brinkman and Reynolds numbers.

The current study intended to discuss a comparative study on the three dimensional Casson nanofluid with nonlinear radiative MHD flow and heat transfer aspects between two parallel stretching/shrinking surfaces. The mathematical models for momentum and temperature are established by employing the boundary layer flow of fluids with spinel-type ferrite MnFe2O4 nanoparticles being distributed in Pure Water/ (H2O) as the base fluid. Remarkable models like Maxwell-Garnett and Patel models are inserted in view of thermal conductivity augmentation. The suitable similarity transformations are adopted for converting the governing non-linear partial differential equations into non-dimensional ODE's and obtaining the relevant parameters for discussion. The major outers of the present study are axial velocity {F′(η)} peters out with amplifying β subject to stretched and shrunk surfaces in relation to both Maxwell-Garnett and Patel models. Growing θw and n exhibits opposite effect on heat transfer rate.

The present investigation imparts the mixed convection non-linear Falkner-Skan flow and heat flux analysis of ZnO-SAE50 nanolubricant over a stationary/moving Riga-plate in presence of thermal radiation. Additionally, velocity and thermal slip boundary conditions are considered. In the current study, a micro-convection model (Patel model) is considered. The present model has great influence in significant enrichment of heat transport capability of the nanoliquids. The similar transformed nonlinear coupled governing expressions are examined numerically by the Runge-Kutta-Fehlberg integration scheme. The important outcome of the present study is that the augmented pressure gradient impedes the motion of nano-lubricant while reverse trend is attained due to the amplification of modified Hartmann number and velocity slip at the boundary. Further, the growth of thermal slip peters out the heat transfer rate from the Riga plate.

The present article has been groomed to explore the boundary-driven magnetized flow of cross nanoliquid over thin needle subject to auto catalysis chemical reactions. In addition to it, the effect of entropy optimization model is incorporated and transportation of heat under non-uniform heat source/sink, Cattaneo-Christov heat flux (rectified Fourier) viewpoint (CCHF), and non-linear thermal radiation is also taken into account. Furthermore, the Brownian and thermophoresis aspects of nanoliquid are invoked. The dimensionless governing equations are solved by apposite shooting scheme. The outcomes of the present study via demonstrated graphs and numerical benchmarks seem to indicate that controlled Sakiadis and Blausius flow pattern of cross nanofluids is attained due to incremented magnetic field strength. Temperature ratio parameter contributes the upgradation of thermal boundary layer thickness and homogenous reaction rate leads to the diminution of nanoparticles concentration. The relative values of needle velocity and the velocity of cross nanofluid are most important factor for the regulation of viscous drag force and rate of heat transportation. Augmented Weissenberg parameter and Reynolds number are the prime factor for the uplift of the flow field and the related layer thickness. Furthermore, the existence of CCHF could result in augmentation in Nusselt.

The main purpose of this investigation is to analyze the flow and heat transfer behavior of a non Newtonian fluid (Oldroyd B fluid) with hybrid nanostructure subject to externally inclined magnetic field. Cattaneo Christov heat flux model is incorporated in the energy equation. Non linear thermal radiation and viscous dissipation mechanisms are considered. Shooting technique is implemented to accomplish the numerical solution. The outcomes of the numerical computations are discussed with the aid of relevant graphs. The performed study reveals that rise in magnetic field strength shows opposite behavior to fluid velocity and temperature. Thermal relaxation time factor controls the rate of heat transportation. Rise in curvature parameter accelerates the fluid flow while that of angle of inclination of magnetic field imparts the reverse effect.

A numerical simulation is presented to investigate the effect of an exponentially varying magnetic field on three dimensional flow of Zinc Oxide-Society of Automotive Engineers 50 nanolubricant (ZnO-SAE50nano-lubricant) past a stretching sheet. Subsequently the impact of homogenous and heterogeneous reactions on the flow of nanolubricant concerned has also taken into account. The study has been strengthened by introducing the convection mechanism and the effect of thermal radiation. Similarity transformations are employed to transform the set of partial governing equations into the set of ordinary differential equations. The suitable boundary conditions are used to obtain the numerical solution. The numerical results are simulated using Matlab bvp4c solver and validated with the existing results. The flow characteristics, thermal characteristics, nanoparticle concentration and some non-dimensional numbers are computed under the influence of the pertinent parameters. The valuable outcome of the current study is that augmented magnetic field strength is the root cause of diminishing axial as well as transverse velocities and growing trend of fluid temperature. Also, the coefficients of homogenous and heterogeneous reactions are boons for ascending concentration boundary layer. Keywords: MHD 3D flow, ZnO-SAE50nano-lubricant, Exponential stretching sheet, Convective heating mechanism, Thermal radiation, Heat generation/absorption

The present investigation draws scholars' attention to the effect of exponential variable viscosity modeled by Vogel and variable permeability on stagnation point flow of Carreau Nanofluid over an electromagnetic plate through a porous medium. Brownian motion and thermophoretic diffusion mechanism are taken into consideration. An efficient fourth-order RK method along with shooting technique are implemented to obtain the required solution of the non-dimensional modeled equations. The contribution of the present study is that augmented electromagnetic field strength due to the suitable arrangement of the plate and that of porosity parameter yield an accelerated motion while that of viscosity parameter produces retarded motion of shear-thickening fluid, contrary to shear-thinning fluid. At the same time, it discusses the inclusion of porous matrix which controls the thermal as well as concentration boundary layers, while enhanced Brownian motion exhibits diametrically opposite trend for them in response to shear-thickening fluid.