Circular rotation of different structures on natural convection of nanofluid-mobilized circular cylinder cavity saturated with a heterogeneous porous medium

The incompressible smoothed particle hydrodynamics (ISPH) method is utilized for studying the circular rotations of three different structures, circular cylinder, rectangle and triangle centered in a circular cylinder cavity occupied by A l 2 O 3 nanofluid. The novelty of this work is appearing in simulating the circular rotations of different solid structures on natural convection of a nanofluid-occupied a circular cylinder. The circular cylinder cavity is suspended by heterogeneous/homogeneous porous media. The embedded structures are taken as a circular cylinder, rectangle and triangle with equal areas. The first thermal condition considers the whole structure is heated, the second thermal condition considers the half of the structure is heated and the other is cooled and the third thermal condition considers the quarter of the structure is heated and the others are cooled. The outer boundary of cylinder cavity is cooled. Due to the small angular velocity ω = 3.15 (low rotational speeds), then the natural convection case will be considered only. The results are representing the temperature, velocity fields. The simulations revealed that the presence of the inner hot/cold structures affects on the velocity distributions and temperature field inside a circular cylinder cavity. The triangle shape has introduced the highest temperature distributions and maximum values of the velocity fields compare to other shapes inside a circular cylinder cavity. The homogeneous porous level reduces the maximum values of velocity field by 25% compared to the heterogeneous porous level.

A Review Study of Numerical Simulation of Lid-Driven Cavity Flow with Nanofluids

Perhaps the most deliberated fluid problem in the field of Computational Fluid Dynamics is the lid driven cavity flow whose simple geometry is used to study the thermal behavior of many engineering applications such as cooling of electronic equipment, solar collectors, thermal storage systems, food processing, solar ponds, crystal growth, lubrication technologies and cooling of electrical and mechanical components. Researchers have been devoting much of their time in order to discover innovative methods to enhance the thermal conductivity of conventional fluids. With the development of nanotechnology, the concept of nanofluids has gained ground considerably as a new kind of heat transfer fluid. Nanofluid is a new kind of fluid with high thermal conductivity is a mixture of solid nanoparticles and a liquid. This review recapitulates the recent progress of the various numerical methods that are used in predicting the influence of several parameters such as type of nanoparticle and host liquid, particle volume concentration, particle size and shape, Brownian diffusion and thermophoresis effect on hydrodynamic and thermal characteristics of convective heat transfer using nanofluids in a lid driven cavity.

Unsteady Hybrid (Ag–CuO/Water) Nanofluid Flow and Heat Transfer due to a Stretching Sheet with Variable Temperature

In this paper, the focal aims are (i) to explore the transient boundary-layer flow and heat transfer of an electrically conducting hybrid (Ag–CuO water) nanofluid along a vertical stretching surface (sheet) having non-zero slot velocity at variable temperature, and (ii) to discuss the influences of momentous parameters involved on the heat transfer and skin friction coefficient graphically. The “Tiwari-Das nanofluid model” is used. The central equations (PDEs) are converted into finite difference equations by the powerful Crank Nicolson technique and numerically solved using the Thomas algorithm. The achieved outcomes for a specific case of the challenge are compared with an analytical solution computed using the Laplace transform technique and discovered to be in excellent accord.

Analysis of Mixed Convection and Free Convection in a Reduced Solar Collector Using a Nanofluid as Heat Transfer Fluid

A three-dimensional investigation of mixed convection which occurs from Al2O3-water nanofluid flow in tube of a reduced solar collector and free convection in air gap situated between cover of solar collector and its absorber was investigated. Heat transmission by conduction in absorber and cover as well as thermal losses to exterior expressed in form of a convective flux have also been taken into account. The different transport equations were solved using CFD-Fluent software which is founded on finite volume method and Boussinesq’s law was introduced to take into account of buoyancy effects. In this investigation, thermal efficiency of solar collector was evaluated and use of nanofluids allows to increase this parameter which is generally low for this kind of thermal systems. Length of thermal regime established in the tube is proposed and this investigation is extended relative to other works developed in this research field. Results obtained gave an idea about the flow structure of the fluid under consideration in a tube of a solar collector and heat transmission mechanisms in air gap and in other elements of the solar collector. These results can facilitate design of this thermal system.

A Comprehensive Review of Nanofluid Heat Transfer in Porous Media

In the present paper, recent advances in the application of nanofluids in heat transfer in porous materials are reviewed. Efforts have been made to take a positive step in this field by scrutinizing the top papers published between 2018 and 2020. For that purpose, the various analytical methods used to describe the flow and heat transfer in different types of porous media are first thoroughly reviewed. In addition, the various models used to model nanofluids are described in detail. After reviewing these analysis methods, papers concerned with the natural convection heat transfer of nanofluids in porous media are evaluated first, followed by papers on the subject of forced convection heat transfer. Finally, we discuss articles related to mixed convection. Statistical results from the reviewed research regarding the representation of various parameters, such as the nanofluid type and the flow domain geometry, are analyzed, and directions for future research are finally suggested. The results reveal some precious facts. For instance, a change in the height of the solid and porous medium results in a change in the flow regime within the chamber; as a dimensionless permeability, the effect of Darcy's number on heat transfer is direct; and the effect of the porosity coefficient has a direct relationship with heat transfer: when the porosity coefficient is increased or decreased, the heat transfer will also increase or decrease. Additionally, a comprehensive review of nanofluid heat transfer in porous media and the relevant statical analysis are presented for the first time. The results show that Al2O3 nanoparticles in a base fluid of water with a proportion of 33.9% have the highest representation in the papers. Regarding the geometries studied, a square geometry accounted for 54% of the studies.

Effect of Aspect Ratios and Sinusoidal Temperature on Heat Exchange Inside Cavity Filled with Hybrid Nanofluids

A mathematical study was conducted for the mixed convection inside a cavity for three aspect ratios filled with hybrid nanofluids by moving the vertical walls down, where the upper wall was thermally isolated, and the two vertical walls with a temperature that is less than the lowest wall’s, which was at a sinusoidal temperature. The investigation and discussion focused on the Richardson numbers (0.1–100), hybrid nanoparticle sizes (0.0–0.08), and the impact of size on the thermal and hydrodynamic properties of hybrid nanoparticles. At lower Richardson numbers, hybrid nanoparticle volume fraction impacts the thermal behaviour model. Besides, it was observed that decreasing the effect of average Nusselt number and nanoparticle size was due to the increase in Richardson numbers.The present results also showed the vital role that sinusoidal temperature has on heat transfer.

Steady of Thermal and Concentration Effect on a Fully Developed Jeffrey Fluid with Baffle in a Vertical Passage

The consistency of the hot effect and concentration on Jeffrey’s fully developed fluid in the vertical passage was examined. We considered two circuits by using a small, efficient aircraft. The more complex ruling ODE is solved by taking the right boundary and co-operative conditions in complex areas. The results are illustrated in a variety of important parameters and are illustrated to analyze important aspects of the results in all confusing areas. It is concluded that the stimulus in the Jeffrey parameter increases the flow rate, temperatures and concentration while the chemical reaction parameter suppresses the flow of fluid in all complex areas. The solutions obtained are compared to DS solved valued and the results hold good consistency. The current results are well supported by the current study of the specific conditions of the mathematical model.

Heat Transfer of Casson Fluid in Poiseuille Flow of Carbon Nanotubes: A Power Series Approach

Combination of Carbon Nanotubes (CNTs) with Human blood as base fluid indicates the enhancement of heat transport in Poiseuille flow and this physical phenomenon could not possible in normal liquids. Usually, when blood cells get touch with external surfaces, the platelets of blood become activated and form blood clots. Therefore, we have considered blood compatible CNT, so that chosen base fluid (blood) can easily pass through it. Due to the higher thermal conductivity, CNTs play an important role to enhance the heat transport in blood flow. These features lead to the novelty of this investigation to study the heat transport of Casson fluid through CNTs in unsteady MHD free convective Poiseuille flow with thermal radiation. Such study consigns practical applications in manufacturing of drugs, biomedical and Tissue engineering, biosensor and other applications in myocardial therapy, neuronal and muscle regeneration. The non-dimensional governing equations are formulated and solved analytically through classical Perturbation Technique and the analysis of results are drawn in smooth curves via MATLAB code. Significant results for different implanted parameters are compared between SWCNT and MWCNT and their significant behaviours are plotted graphically. The obtained results indicate that Casson parameter accelerates the flow velocity for MWCNT and SWCNT. Furthermore, interesting behavior on the outlines of velocity for SWCNT and MWCNT due to the presence of Schmidt number, Peclet number and Reynolds number are detected. Comparison with previously published work has been inspected and originated excellent agreement.

Simulation of Nonlinear Viscous Fingering in a Reactive Flow Displacement: A Multifractal Approach

fractal analysis of viscous fingering of a reactive miscible flow displacement in homogeneous porous media is investigated and multifractal spectrum, and fractal dimension are introduced as two essential features to characterize the irregularity of finger patterns. The Reaction of the two reactant fluids generates a miscible chemical product C in the contact zone. Considering the similarity between chemical products and coastline, monofractal and multifractal analyzes are performed. In monofractal analysis, the box-counting method is implemented on binary images and in multifractal analysis, due to the image processing; the fractal characteristics of viscous fingering instability are analyzed by means of fractal quantities such as Holder exponent, multifractal spectrum, f (α)-image and fractal dimension dynamics. Fractal analysis shows that the fractal dimension increases with time. Also, by considering five different nonlinear simulations, the results show that in the case both sides of the chemical product C are unstable, the multifractal spectrum curve has the highest peak, which means the more complex finger patterns lead to more values of fractal dimension. In addition, a comparison between different values of Ar is conducted and the results show similar behavior. However, small value of aspect ratio leads to a broader width of the multifractal spectrum curve. Furthermore, f (α)-images of concentration contour were investigated for different precisions and some undetectable finger patterns were observed in these images. It can be concluded that the use of f (α)-image represents more detailed image than concentration contours.

Hybrid Nanofluid Heat and Mass Transfer Characteristics Over a Stretching/Shrinking Sheet with Slip Effects

Unsteady magneto-hydrodynamic heat and mass transfer analysis of hybrid nanoliquid flow over stretching/shrinking surface with chemical reaction, suction, slip effects and thermal radiation is analyzed in this problem. Combination of Alumina (Al2O3) and Titanium Oxide (TiO2) nanoparticles are taken as hybrid nanoparticles and base fluid is taken as water. Using similarity transformation method the governing equations are changed in to set of ordinary differential equations. These resultant equations are numerically evaluated by utilizing Finite element method. The influence of several pertinent parameters on fluids temperature, concentration and velocity is calculated and the outcomes are plotted through graphs. The values of non-dimensional rates of heat transfer, mass transfer and velocity are also analyzed and the outcomes are represented in tables. Temperature sketches of hybrid nanoliquid intensified in both unsteady and steady cases as volume fraction of both nanoparticles rises.

Coupled plasmons in aluminum nanoparticle superclusters

Metallic nanoparticles can self-assemble into highly ordered superclusters for potential applications in optics and catalysis. Here, using first-principles quantum mechanical calculations, we investigate plasmon coupling in superclusters made of aluminum nanoparticles. More specifically, we study/compare the plasmon coupling in close-pack FCC (face-centered-cubic) and non-close-pack BCC (body-centered-cubic) superclusters. We demonstrate that the optical properties of these clusters can be fine-tuned with respect to the packing arrangement. As a key result of this work, plasmon coupling is found to be enhanced (diminished) in FCC (BCC) superclusters due to constructive (destructive) plasmon coupling. Our quantum calculations would help in the design of Al-based superclusters beneficial for plasmonics applications.

Unsteady Radiative Flow of Particular Nanoliquids Along an Infinite Vertical Flat Plate in the Proximity of Convective Boundary Condition

In this article, the heat transfer and flow pattern characteristics are restudied in the proximity of convective boundary condition for three kinds of nanoliquids, namely copper oxide-water nanoliquid (CuO–H2O), silverwater nanoliquid (Ag–H2O), and titanium dioxide-water nanoliquid (TiO2–H2O). The thermal radiation impact is assumed into account. The partial differential equations are shifted into ordinary differential equations by applying an acceptable transformation and then exact solutions are acquired by promoting the Laplace transform technique. Solid volume fraction is fluctuated as 5%, 10%, 15%, and 20%. The variations of nanoliquid motion and energy transmit are displayed graphically as well as the numerical values of friction factor and rate of heat transfer at the plate are displayed in tabular pattern. In particular, the least shear stress occurs for silverwater nanoliquid and the greatest shear stress occurs for titanium dioxide-water nanoliquid as well as the least heat transfer coefficient occurs for titanium dioxide-water nanoliquid and the greatest heat transfer coefficient occurs for copper oxide-water nanoliquid. This report can be further utilized to authenticate the effectiveness of acquired mathematical results for another sophisticated nanoliquid stream problems.

Impact of Melting Heat Transfer Analysis in MoS2 and MgO Nanoparticles

In this extraordinary work, heat transfer examined around boundary layer of nanofluids MoS2–H2O and MgO–H2O. Micropolar ferrofluid is addressed in this investigation. Energy equation can be elaborated by employing Cattaneo-Christov heat flux analysis with relevant thermal conductivity. This article manages Darcy-Forchheimer. Disturbance in stretchable sheet has been represented by Darcy Forchheimer expression. Mixed convection heat flow at the incidence of melting effect from a stretching surface embedded in a porous medium is described. Governing PDE’s of current analysis are lessen into a set of ODE’s using requisite congruity transformations. Set of similarity equations can be fixed out with RKF-45. Achievements of distinct parameters on f′, θ distributions are represented by the aid of graphs.

Insight into the Dynamics of Water Conveying Silver and Aluminium Oxide Nanoparticles on a Moving Cylinder Subject to Variable Surface Temperature and Lorentz Force

MHD and variable surface temperature are examined numerically in this article to see how they affect the unsteady type natural convection flow of a hybrid nanofluid on a moving vertical cylinder. Nanoparticles of Ag and Al2O3 are considered in the water-based hybrid nanofluid. Using the Crank-Nicolson method, the equations governing flow and heat transport are unravelled. To test the present numerical approach validity, the results are matched to those found in the literature for similar problems and found to be extremely congruent with those findings. Analysis of temperature and velocity portraits, as well as Cf (skin friction coefficient) and Nux (Nusselt number) for each vital parameter, has been illustrated. This study found that by escalating the magnetic parameter, Nux and Cf of Ag–Al2O3/water can be reduced. Also, increasing Gr can be used to augment the Cf and Nux of Ag–Al2O3/water. Further, by increasing δ2, a lower skin friction coefficient and a higher Nusselt number can be achieved. The current findings are useful to the thermal flow processing of magnetic nanomaterials in the metallurgy industries and chemical engineering.

Mass Diffusion Effect on Magneto Hydrodynamic (MHD) Unsteady Free Convective Flow with Viscous Dissipation and Radiation Absorption

The current research analyzed unsteady viscous dissipation, comprehensive radiation absorption consequence on hydrodynamic free-convective movement on perpendicular porous plate beyond chemical reaction and heat generation. Doufour effect is also introduced to solve utilizing multiple perturbation law momentum, heat and mass fields of outcome are inspected through pertinent parameters. Doufour consequence and comprehensive thermal radiation enhances it tends to enhance in duel temperature. Skinfriction, Nusselt number is diminished when enhancing Prandtl number. Skinfriction, Sherwood number and Nusselt number are examined.

Investigation of Nonlinear Fluid Flow Equation in a Porous Media and Evaluation of Convection Heat Transfer Coefficient, by Taking the Forchheimer Term into Account

The steady-state fully developed fluid flow in a channel filled with porous media is known as one of the classical issues in the field of fluid mechanics. Darcy’s, Brinkman’s and Brinkman-Forchheimer’s laws are well-known models for describing this kind of fluid. Darcy equation, as the most useful equations, is based on the description of fluid friction and porous matrix. In Brinkman equation, the term of viscosity similar to that of Laplacian in the Navier Stokes equation is added to the Darcy equation, and finally, Forchheimer term is able to account for second-order drag term due to the impact of solid in the fluid. Adding the Forchheimer term to the Darcy-Brinkman equation causes the nonlinearity of the equation. In this research, an analytical solution for several flow models in a porous medium channel is provided. The simplicity of use of the velocity profile, particularly for the study of the heat transfer problem and the exergy analysis of flow, is the most essential feature of the suggested approach. In addition to the analytical response of this equation, the convective heat transfer coefficient is estimated. The impacts of all parameters on the the Nusselt number are evaluated. The findings reveal that when the Forchheimer coefficient rises, the Nusselt number falls; this downward trend is sharp in smaller Darcy numbers; hence Nusselt number tends to its asymptotic values. While, as Darcy number increase, the downtrend is getting close to a linear one.

Analysis of entropy production in a bi-convective magnetized and radiative hybrid nanofluid flow using temperature-sensitive base fluid (water) properties

The heat transport characteristics, flow features, and entropy-production of bi-convection buoyancy induced, radiation-assisted hydro-magnetic hybrid nanofluid flow with thermal sink/source effects are inspected in this study. The physical characteristics of hybrid nanofluids (water-hosted) are inherited from the base liquid (water) and none has considered the physical characteristics of base liquid (water) in the study of temperature-sensorial hybrid nanofluid investigations, though the water physical characteristics are not constants in temperature variations. So, the temperature-sensorial attributes of base liquid (water) are taken into account for this hybrid nanofluid ([Formula: see text]) flow analysis. The mathematical forms of the flow configuration (i.e., the set of coupled, nonlinear PDE form of governing equations) are solved by utilizing the subsequent tasks: (i) congenial transformation; (ii) quasilinearization; (iii) methods of finite differences to form block matrix system, and (iv) Varga's iterative algorithm. The preciseness of the whole numerical procedure is ensured by restricting the computation to follow strict convergence conditions. Finally, the numerically extracted results representing the impacts of various salient parameters on different profiles ([Formula: see text]), gradients, and entropy production are exhibited in physical figures for better perception. A few noticeable results are highlighted as: velocity graph shows contrast behaviour under assisting and opposing buoyancy; temperature ([Formula: see text]) is dropping for heightening heat source ([Formula: see text]) surface friction remarkably declines with the outlying magnetic field ([Formula: see text]); thermal transport confronts drastic abatement under radiation ([Formula: see text]), and [Formula: see text]; the characteristics Reynolds and Brinkman numbers promote entropy. Furthermore, the bounding surface acts as a strong source of [Formula: see text]-production. Summarizations are listed at the end to quantify percentage variations.

Analytical Study on Magnetohydrodynamic Nanofluid Flow Influenced by Electrical Conductivity in a Baffled Vertical Channel

The theoretical analysis of the steady fully developed electrically conducting flow of water based nanofluid in a vertical double passage channel is studied. The governing equations are respectively solved analytically and semi-analytically for each flow using perturbation method and the differential transformation method (DTM). The effects of flow governing parameters on the flow and velocity fields are numerically evaluated and presented in the graphical form. The outcome obtained by semi analytical method is confirmed by comparing with the aid of perturbation method and good agreement is found.

Effects of Wu’s Slip and Non-Uniform Source/Sink on Entropy Optimized Radiative Magnetohydrodynamic Up/Down Flow of Nanofluids

The main goal of this article is to examine the influence of shape factors, Wu’s slip, non-uniform heat source/sink on the radiative up and down hydromagnetic flow of SWCNT/MWCNT-water nanofluid past moving thin vertical needle. Entropy optimization analysis is carried out. Brick, Cylinder, Platelet and Blade shapes of nanoparticles are considered. Numerical solutions are attained by well-known shooting technique. The comprehensive discussion regarding the effects of physical parameters on velocity, temperature, skin friction coefficient and local Nusselt number is carried on. Outcomes reveal that fluid velocity behaves in opposite manner in up and down flows of nanofluids in the presence of increasing magnetic field strength and second order slip. Strengthening of solid volume fractions contributes greater surface drag in both up and down flows. Moreover, the shape effects of various kinds of SWCNT/MWCNT nanoparticles are studied and we visualized that the rate of heat transfer is augmented when the platelet shape of SWCNT/MWCNT nanoparticles are chosen.

Three-Dimensional Study of Magnetohydrodynamic Natural Convection, Entropy Generation, and Electromagnetic Variables in a Nanofluid Filled Enclosure Equipped with Inclined Fins

This article provides a numerical study on carbon nanotube-water nanofluid convection in a three-dimensional cavity under a magnetic field effect. Two walls are kept at a hot temperature, and the upper and lower horizontal walls are considered adiabatic. As a new configuration, the beneficial effect of using a nanofluid is coupled with the incorporation of cold V-shape obstacle placed in the cubic cavity; in addition, an external magnetic field is applied toward the horizontal x-axis direction. The finite element method based on the Galerkin's Weighted Residual technique is used to solve the three-dimensional governing equations. In this paper, the ranges of the parameters used are the Hartmann number, varied from 0 to 100, Rayleigh number from 10³ to 10⁵, nanofluid volume fraction between 0% and 4.5%, and the body V-shaped opening angle varied from 0 to 80°. The effect of the obstacle shape and the added nanoparticle concentration on the flow behaviors, the different instabilities generated, and the heat transfer exchanged were exposed. An enhancement in heat transfer was recorded by increasing the obstacle opening angle and the volume fraction of the carbon nanotubes. Special attention has also been devoted to the calculation of the different kinds of entropy generations.

Magneto-Hydrodynamics Natural Convection and Entropy Production in a Hollow Cavity Filled with a Nanofluid

In this research work, we present a study of the magnetic field impact on the flow of AL2O3-water nanofluid which results from natural convection that occurs inside a cavity having a particular shape. For this study a monophasic model is used. As resolution of the different equations which describe the physical phenomenon to be studied is difficult, the use of Ansys-Fluent software appears essential to do this task. An analysis of the impacts of Rayleigh numbers (7.68.104, 1.5.105 and 3.072.105) and Hartmann numbers (0 to 75) as well as the concentration of nanoparticles expressed as a percentage (0 to 5%) on heat transmission and entropy production was performed. Numerical results obtained confirm that mean Nusselt number and entropy production vary proportionally with Rayleigh number and the particles concentration and they are inversely proportional to Hartmann number. Based on the results obtained, improvement in thermal performance depends on the nanoparticles concentration. Correlations for Nusselt number expressed as an equation of two variables which are Hartmann and concentration of the nanoparticles have been proposed to predict the rate of heat transmission inside the enclosure.

Effects of Viscous Dissipation and Thermal Radiation on an Electrically Conducting Casson-Carreau Nanofluids Flow with Cattaneo-Christov Heat Flux Model

The primary goal of this research is to study the Cattaneo-Christov heat flux model on the impacts of mass and energy transit of MHD Casson-Carreu nanofluid through a permeable vertical accelerating plate with Soret and Dufour mechanism. The non-Newtonian fluids flowed over the porous vertical plate to reach the boundary layer in this investigation. In order to understand the physical model, partial differential equations (PDEs) are used. To get a linked nonlinear set of ordinary differential equations (ODEs), we reduced this set of PDEs by using similarity variables. SHAM, a spectrum basis technique, was utilized to solve these modified equations to understand the physical significance. A good method is to utilize SHAM to decouple the coupled nonlinear ODE systems and divide them into linear and nonlinear equation sets since this helps to separate the systems. As a result, the two non-Newtonian fluids (Carreu and Cassin) flow together through the vertical wall and into the boundary layer, where different parameters’ impacts are scrutinized. The current results showed that an upturn in the Casson parameter (β) degenerates the boundary layer velocity and the total thickness. Upturn in the Weissenberg number (We) on the other hand, raises the velocities and temperatures in both directions. Additionally, increasing the Soret and Dufour parameters sped up the velocity graph.

Significance of Rosseland’s Radiative Process on Reactive Maxwell Nanofluid Flows over an Isothermally Heated Stretching Sheet in the Presence of Darcy–Forchheimer and Lorentz Forces: Towards a New Perspective on Buongiorno’s Model

This study aimed to investigate the consequences of the Darcy–Forchheimer medium and thermal radiation in the magnetohydrodynamic (MHD) Maxwell nanofluid flow subject to a stretching surface. The involvement of the Maxwell model provided more relaxation time to the momentum boundary layer formulation. The thermal radiation appearing from the famous Rosseland approximation was involved in the energy equation. The significant features arising from Buongiorno’s model, i.e., thermophoresis and Brownian diffusion, were retained. Governing equations, the two-dimensional partial differential equations based on symmetric components of non-Newtonian fluids in the Navier–Stokes model, were converted into one-dimensional ordinary differential equations using transformations. For fixed values of physical parameters, the solutions of the governing ODEs were obtained using the homotopy analysis method. The appearance of non-dimensional coefficients in velocity, temperature, and concentration were physical parameters. The critical parameters included thermal radiation, chemical reaction, the porosity factor, the Forchheimer number, the Deborah number, the Prandtl number, thermophoresis, and Brownian diffusion. Results were plotted in graphical form. The variation in boundary layers and corresponding profiles was discussed, followed by the concluding remarks. A comparison of the Nusselt number (heat flux rate) was also framed in graphical form for convective and non-convective/simple boundary conditions at the surface. The outcomes indicated that the thermal radiation increased the temperature profile, whereas the chemical reaction showed a reduction in the concentration profile. The drag force (skin friction) showed sufficient enhancement for the augmented values of the porosity factor. The rates of heat and mass flux also fluctuated for various values of the physical parameters. The results can help model oil reservoirs, geothermal engineering, groundwater management systems, and many others.

Impact of packing arrangement on the optical properties of C60 cluster aggregates

The packing arrangement of organic π-conjugated molecules in a nanoscale material can have a strong impact on their optical properties. Here, using real-time-propagation time dependent density functional theory (rt-TDDFT) calculations with the support of transition contribution maps, we study how modifications in the packing arrangement (cubic-like and chain-like aggregates composed of eight C60 molecules) and packing density (assembled at close distances with center-to-center inter-fullerene distances (d) varying from 9 Å to 11 Å) of C60 molecules affect the optical properties of cluster aggregates. The important conclusions drawn from this work are summarized as follows. For d = 9 Å, the charge transfer excitons produced by cubic and chain-like C60 cluster aggregates have highly different optical characteristics, as evidenced by the transition contribution maps. On the other hand, for d = 10 Å and 11 Å, both kinds of aggregates produce qualitatively similar optical features with the emergence of Wannier-like delocalized excitons having distinct degrees of localization and spatial distribution. The theoretical findings in this study elucidate the optical excitations in C60 cluster aggregates and could help in the design of more efficient organic devices.

A Bi-Convective Magnetized Hybrid Nanofluid Flow Along with Thermal Radiation in an Adverse Pressure Field Using Temperature-Sensitive Base Fluid (Water) Properties

This investigation considers the temperature-sensitive characteristics of water (base fluid) to scrutinize the flow mechanism, various essential gradients and energy distribution (by means of entropy production) in a magnetized hybrid nanofluid (Cu+Al2O3+H2O) flow with exponentially increasing pressure. For more mechanically realistic results, the analysis includes radiation and heat generation/absorption along with surface mass disposal. Thermophoretic diffusion and Brownian diffusion (Nt, Nb) are incorporated into this study as essential slip mechanisms. The governing physical principles in mathematical form are solved utilizing a robust numerical method with Varga’s block matrix method. The graphical demonstrations of numerical results show that velocity heightens with mixed convection (λ) and Reynolds number (Re) whereas temperature enhances for heat source (Q > 0) and injection (A < 0). Stuart Number (St) reduce the heat transfer performance while mixed convection (λ) enhances the frictional coefficient. This study further found that improving estimations of nanoparticles’ percentage (Φ), Re, Eckert number (Ec) and suction (A > 0) significantly generating more entropy.

Free Energy Surfaces and Barriers for Vacancy Diffusion on Al(100), Al(110), Al(111) Reconstructed Surfaces

Metadynamics is a popular enhanced sampling method based on the recurrent application of a history-dependent adaptive bias potential that is a function of a selected number of appropriately chosen collective variables. In this work, using metadynamics simulations, we performed a computational study for the diffusion of vacancies on three different Al surfaces [reconstructed Al(100), Al(110), and Al(111) surfaces]. We explored the free energy landscape of diffusion and estimated the barriers associated with this process on each surface. It is found that the surfaces are unique regarding vacancy diffusion. More specically, the reconstructed Al(110) surface presents four metastable states on the free energy surface having sizable and connected passage-ways with an energy barrier of height 0.55 eV. On the other hand, the reconstructed Al(100)/Al(111) surfaces exhibit two/three metastable states, respectively, with an energy barrier of height 0.33 eV. The findings in this study can help to understand surface vacancy diffusion in technologically relevant Al surfaces.

Thermal Analysis of the Solar Collector Cum Storage System Using a Hybrid-Nanofluids

The main problem in the solar energy field is the storage of thermal energy. To divert this problem, it was suggested to use a flat-plat solar collector which also serves as a storage system; this solution will reduce the size of a refrigerating machine that we are studying. A high stored energy density is only possible if we through use latent heat of phase change. Thermal analysis has been developed for this type of storage collector for near-steady state conditions using a nanofluid heat storage substance depended on KNO3–NaNO3 binary salt mixture as PCM and a mix of Al2O3–SiO2 as nanoparticle, from which the new Hottel-Whillier-Bliss equations have been used for efficient flat plate collector. Computations were achieved for a large variety of parameters to verify the significance of the created model.

Review of Nanofluids and Their Biomedical Applications

Numerous researchers have reported significant improvements in nanofluid (NF) heat transfer (HT), suspension stability, thermal conductivity (TC), and rheological and mass transfer properties. As a result, nanofluids (NFs) play an important role in a variety of applications, including the health and biomedical engineering industries. The majority of the nanofluids (NFs) literature focuses on analyzing and comprehending the behavior of nanofluid models as heating or cooling mechanisms in various fields. This article represents a comprehensive study on nanofluids (NFs). It involves commonly used nanoparticles (NPs), magnetic nanofluids (MNFs), thermal conductivity (TC) enhancement, heat transfer (HT) enhancement, nanofluids (NFs) synthesis methods, stability evaluation methods, stability enhancement, nanofluids (NFs) applications in the biomedical field, and their impact on health and the environment. Nanofluids (NFs) play vital role in biomedical applications. It can be implemented in drug delivery systems, hyperthermia, sterilization processes, bioimaging, lubrication of orthopedic implants, and micro-pumping systems for drugs and hormones.

Numerical and Statistical Analysis of Dissipative and Heat Absorbing Graphene Maxwell Nanofluid Flow Over a Stretching Sheet

This paper is basically devoted to carry out an investigation regarding the unsteady flow of dissipative and heat absorbing hydromagnetic graphene Maxwell nanofluid over a linearly stretched sheet taking momentum and thermal slip conditions into account. Ethylene glycol is selected as a base fluid while graphene particles are considered as nanoparticles. The highly nonlinear mathematical model of the problem is converted into a set of nonlinear coupled differential equations by means of fitting similarity variables. Further, Runge-Kutta Fehlberg algorithms along with the shooting scheme are instigated to analyse the numerical solution. The variations in graphene Maxwell nanofluid velocity and temperature owing to different physical parameters have been demonstrated via numerous graphs whereas Nusselt number and skin friction coefficients are illustrated in numeric data form and are reported in different tables. In addition, a statistical method is implemented for multiple quadratic regression estimation analysis on the numerical figures of wall velocity gradient and local Nusselt number to establish the connection among heat transfer rate and physical parameters. Our numerical findings reveal that the magnetic field, unsteadiness, inclination angle of magnetic field and porosity parameters boost the graphene Maxwell nanofluid velocity while Maxwell parameter has a reversal impact on it. The regression analysis confers that Nusselt number is more prone to heat absorption parameter as compared to Eckert number. Finally, the numerical findings are compared with those of earlier published articles under restricted conditions to validate the numerical solution. The comparison of numerical findings shows an excellent conformity among the results.

A Numerical Approach to the Modeling of Thomson and Troian Slip on Nonlinear Radiative Microrotation of Casson Carreau Nanomaterials in Magnetohydrodynamics

The goal of the current work is to explore the influence of Thompson and Troian slip on the hydromagnetic microrotations of Carreau nanomaterials over a linearly stretched surface subject to NLTR, viscous dissipation, Newtonian heating, homogenous and heterogeneous reactions. Effect of non linear slip (Thompson and Troian slip) on non Newtonian nanofluid (Carreau nanofluid) subject to microrotation is the novelty of the investigation. Shooting technique is the instrumental to get appropriate numerical solution. The significant outcomes of the current study are that Casson parameter and Weissenberg number exhibit opposite results for velocity and heat transfer rate due to flow of micropolar Carreau nanofluid. Further, more and more Thompson and Troian slip yields diminution of flow velocity as well as microrotations. Amplifying Casson parameter intensifies the HTR from the stretched surface.

Three-Dimensional Rotating Flow of an Oldroyd-B Nanofluid with Relaxation-Retardation Viscous Dissipation

The principal aim of this study is to explore the impact of relaxation-retardation viscous dissipation, nonlinear convection, variable chemical reaction, and nonlinear thermal radiation on the three-dimensional rotating flow of an Oldroyd-B nanofluid over an exponentially extended surface. The Buongiorno model that takes into account the Brownian movement and thermophoresis responsible for nanoparticle motion. Exponentially varying temperature and concentration associated with convective heat transfer coefficients are assumed in the boundary conditions. The system of dimensionless ODEs is solved by the spectral quasi-linearization method. The results of the analysis show, among other results that the relaxation time parameter opposes the momentum transport while assisting heat transportation. The retardation time parameter acts to support momentum growth while reducing and resists heat transport. The present study focused on the investigation the effect of relaxation and retardation viscous dissipation on rotating flow of a non-Newtonian fluid (Oldroyd B fluid) past an exponential stretching sheet.

Hall Effects on Unsteady Magnetohydrodynamic Flow of a Nanofluid Past an Oscillatory Vertical Rotating Flat Plate Embedded in Porous Media

In the current investigative paper, the impact of Hall current on an unsteady magnetohydrodynamic liberated convection revolving flow of a nanofluid restricted with a uniform absorbent medium over an oscillatory moving vertical smooth plate with convective as well as diffusive frontier conditions has been reviewed. The non-dimensionalized governing differential equations by the appropriate frontier conditions are resolved by the perturbations technique. The impacts of the physical constants on the flow as well as the heat transfer features are displayed graphically and analyzed for Cu as well as Al2O3 nanoparticles. For the engineering industry, the skin friction coefficient, local Nusselt number, along with the Sherwood’s number are examined numerically in detail.

Significance of Stefan Blowing and Convective Heat Transfer in Nanofluid Flow Over a Curved Stretching Sheet with Chemical Reaction

The applications of fluid flow with Newtonian heating effect include conjugate heat conveyance around fins, petroleum industry, and heat exchangers designing. Motivated from these applications, an attempt has been made to analyze the stream of viscous nanomaterial subjected to a curved stretching sheet. Also, heat and mass transport mechanism due to a chemical reaction, Brownian and thermophoresis motion are discussed. The equations of the mathematical model are formulated by considering the Newtonian heating and Stefan blowing conditions at the boundary. These modelled equations are then changed to a system of nonlinear equation involving ordinary derivatives of a function by means of suitable similarity transformations. Further, shooting technique with Runge-Kutta-Fehlberg-45 process is utilized to solve the reduced equations. Outcomes disclose that, the gain in Stefan blowing parameter escalates the liquid velocity. The intensification in chemical reaction rate parameter deteriorates the concentration gradient. The rise in Schmidt number and thermophoresis parameter drops the mass transfer rate. The increased values of Newtonian heating parameter with respect to thermophoresis parameter decays the heat transport rate.

A Review on the Use of Hybrid Nanofluid in a Solar Flat Plate and Parabolic Trough Collectors and Its Enhanced Collector Thermal Efficiency

Energy demand is high in all parts of the world, mostly in all industrial sectors. To meet the energy demand the fossil fuel is the only way. Due to rapid industrial growth and use of fossil fuel result in global warming and environmental pollution. Moreover, the limited availability of the fossil fuels, it is necessary to depend on the renewable energy sources. Promising renewable energy in the world is solar energy, which is available largely on the earth surface. The solar energy can be converted into thermal energy in the solar flat plate collector. The collector thermal efficiency is purely depends on the working fluid used in it. Most of the studies revealed that replacing the working fluid with high thermal conductivity fluids called as nanofluids and hybrid nanofluids can improve the collector thermal efficiency. Few decades back studies have been conducted with nanofluids in solar collectors. Currently the researchers are working on solar collectors for further improvement of its efficiency using hybrid nanofluids. In this review paper, we will discuss about the synthesis of hybrid nanoparticles, hybrid nanofluids, characterization, thermophysical properties, and application of hybrid nanofluids in solar flat plate collector under natural and forced circulation of fluid. The research gap in the solar collector is also discussed in this article. This paper also explains about the heat transfer capabilities of hybrid nanofluids especially used solar collectors.

Thermal Slip Flow of a Three-Dimensional Casson Fluid Embedded in a Porous Medium with Internal Heat Generation

Present assessment is considered to analysis flow as well as heat characteristics of steady, thermal slip flow of three-dimensional Casson fluid embedded in a porous medium with internal heat generation. Geometry of the present analysis is linearly stretched surface. Later, all the PDEs corresponding to the study are altered to set of nonlinear equations ODEs by means of appropriate similarity transformations. An efficient numerical scheme of spectral relaxation method (SRM) is applied to solve the nonlinear ordinary system. Variations of Nusselt number, temperature, velocity, and local skin friction coefficient with fluid parameters exhibited by graphs and tables. Spectral relaxation method gives an exact convergence to the nonlinear boundary value problems compare with general methods. In this study, to improve the precision and accuracy of the SRM successive over-relaxation (SOR) strategy is utilized. Proposed method as well as outcomes is checked with the comparison. A sensible connection is acquired between the current outcomes and accessible outcomes in writing. Some of the observations are skin friction coefficient raises and velocities decreases by the magnetic field strength. Skin friction and Local Nusselt number at the surface is more pronounced for non-Newtonian case than that of Newtonian case.

Blood Flow Mediated Hybrid Nanoparticles in Human Arterial System: Recent Research, Development and Applications

Blood flow dynamics contributes an elemental part in the formation and expansion of cardiovascular diseases in human body. Computational simulation of blood flow in the human arterial system has been widely used in recent decades for better understanding the symptomatic spectrum of various diseases, in order to improve already existing or develop new therapeutic techniques. The characteristics of the blood flow in an artery can be changed significantly by arterial diseases, such as aneurysms and stenoses. The progress of atherosclerosis or stenosis in a blood vessel is quite common which may be caused due to the addition of lipids in the arterial wall. Nanofluid is a colloidal mixture of nanometer sized (which ranges from 10–100 m) metallic and non-metallic particles in conventional fluid (such as water, oil). The delivery of nanoparticles is an interesting and growing field in the development of diagnostics and remedies for blood flow complications. An enhancement of nano-drug delivery performance in biological systems, nanoparticles properties such as size, shape and surface characteristics can be regulated. Nanoparticle offers remarkably advantages over the traditional drug delivery in terms of high specificity, high stability, high drug carrying capacity, ability for controlled release. Highly dependency has been found for their behavior under blood flow while checking for their ability to target and penetrate tissues from the blood. In the field of nano-medicine, organic (including polymeric micelles and vesicles, liposomes) and inorganic (gold and mesoporous silica, copper) nanoparticles have been broadly studied as particular carriers because as drug delivery systems they delivered a surprising achievement as a result of their biocompatibility with tissue and cells, their subcellular size, decreased toxicity and sustained release properties. For the extension of nanofluids research, the researchers have also tried to use hybrid nanofluid recently, which is synthesized by suspending dissimilar nanoparticles either in mixture or composite form. The main idea behind using the hybrid nanofluid is to further improve the heat transfer and pressure drop characteristics. Nanoparticles are helpful as drug carriers to minimize the effects of resistance impedance to blood flow or coagulation factors due to stenosis. Discussed various robust approaches have been employed for the nanoparticle transport through blood in arterial system. The main objective of the paper is to provide a comprehensive review of computational simulations of blood flow containing hybrid-nanoparticles as drug carriers in the arterial system of the human body. The recent developments and analysis of convective flow of particle-fluid suspension models for the axi-symmetric arterial bodies in hemodynamics are summarized. Detailed existing mathematical models for simulating blood flow with nanoparticles in stenotic regions are reviewed. The review focuses on selected numerical simulations of physiological convective flows under various stenosis approximations and computation of the temperature, velocity, resistance impedance to flow, wall shear stress and the pressure gradient with the corresponding boundary conditions. The current review also highlights that the drug carrier nanoparticles are efficient mechanisms for reducing hemodynamics of stenosis and could be helpful for other biomedical applications. The review considers flows through various stenoses and the significances of numerical fluid mechanics in clinical medicine. The review examines nano-drug delivery systems, nanoparticles and describes recent computational simulations of nano-pharmacodynamics.

Significance of Magnetic Field on Carreau Dissipative Flow Over a Curved Porous Surface with Activation Energy

This paper theoretically clarifies the impact of pertinent parameters, including viscous dissipation on the flow of Carreau fluid through a permeable arched elongating sheet. Flow describing equations are metamorphosed as ODEs and executed using the combination of shooting and Runge-Kutta strategies. Consequences are elucidated using tables and graphs. We discovered that (a) an appreciable decline in the concentration against temperature difference and reaction rate parameters (b) curvature parameter and porosity parameters registered opposite behaviour to each other on velocity profile (c) there is a reduction in the heat transfer rate with larger Eckert number and curvature parameters (d) Biot number ameliorates the temperature and local Nusselt number (e) Schmidt number and activation energy parameters are showing different behaviours on local Sherwood number. And also, magnetic field and porosity parameters minimize the velocity and surface drag force and Biot number ameliorates the temperature. Further, present results are validated with the earlier outcomes and perceived an acceptable agreement.

Numerical study of heat generating γ Al 2 O 3 - H 2 O nanofluid inside a square cavity with multiple obstacles of different shapes

A numerical research on uniformly heat generating γ Al₂O₃–H₂O nanofluid filled square cavity with multiple obstacles of different shapes is carried out. The cavity is assumed to be heated at bottom and cooled by vertical walls with linearly varying temperature. An adiabatic condition is assumed at the top of the cavity. Circular, square and triangular shaped obstacles are considered. The mathematical model has been solved using Galerkin finite element method. Results are presented for streamlines, isotherms, local and mean Nusselt numbers. Multiple rotating cells are observed in the streamlines. It is found that the local and mean Nusselt numbers increase with nanoparticle volume fraction and higher heat transfer is achieved in the cavity with triangular obstacles.

Hydromagnetic Effects on Hybrid Nanofluid (Cu–Al2O3/Water) Flow with Convective Heat Transfer Due to a Stretching Sheet

In this paper, transient free convective boundary layer flow of a viscous hybrid nanofluid due to a vertical stretching sheet with MHD effects is studied numerically using the Crank Nicolson finite difference numerical technique. To explore the properties of heat transfer and the flow field due to a vertical stretching sheet in the existence of a Lorentz force, two different fluids, specifically Cu–Al2O3/water and Cu/water, are utilized. The results of different physical parameters and the practical quantities of concern that they affect are investigated. According to this article’s results, Cu–Al2O3/water has a superior heat transfer rate than Cu/water in a magnetic field setting. Various other nano mixtures can be attempted to attain the optimal heat transfer rate.

Entropy Generation in Magnetized Bioconvective Nanofluid Flow Along a Vertical Cylinder with Gyrotactic Microorganisms

This paper presents the analysis of thermal optimization in magnetic materials based on the entropy generation in a mixed convective MHD flow of an electrically conductive nano liquid having motile microorganisms together with a vertical cylinder. By using the convection boundary condition, the process of heat transport is examined in detail. With coupled linear boundary conditions the related equations (continuity, momentuum and energy) are reduced to five ODE’s. The RKF-4,5 method by shooting algorithm was employed to examine variation of physical parameters under study. The resuts of vital physical parameters on the wall friction, Nusselt number, mass flux, wall of motile microorganism flux, along with velocity profiles, temperature, concentration of nanopar-ticles, and density of motile microbes, were studied in detail. It is detected that heat transport rate is 0.81% greater for cylindrical surface compared to flat plate surface.

Thermo-Solutal Convection of a Nanofluid Utilizing Fourier’s-Type Compass Conditions

Nanotechnology has infiltrated into duct design in parallel with many other fields of mechanical, medical and energy engineering. Motivated by the excellent potential of nanofluids, a subset of materials engineered at the nanoscale, in the present work, a new mathematical model is developed for natural convection in a vertical duct containing nanofluid. Numerical scrutiny for the double-diffusive free and forced convection within a duct encumbered with nanofluid is performed. Buongiorno’s model is deployed to define the nanofluid. Robin boundary conditions are used to define the surface boundary conditions. Thermal and concentration equations envisage the viscous, Brownian motion, thermosphores of the nanofluid, Soret and Dufour effects. Using the Boussi-nesq approximation the solutal buoyancy effect as a result of gradients in concentration are incorporated. The conservation equations which are nonlinear are numerically estimated using fourth order Runge-Kutta methodology and analytically ratifying regular perturbation scheme. The mass, heat, nanoparticle concentration and species concentration fields on eight dimensionless physical parameters such as thermal and mass Grashof numbers, Brownian motion parameter, thermal parameter, Prandtl number, Eckert number, Schmidt parameter, and Soret parameter are calculated. The impact of these parameters are outlined pictorially. The velocity and temperature fields are boosted with the thermal Grashof number. The Soret and the Schemidt parameters reduces the nanoparticle volume fraction but it heightens the momentum, temperature and concentration. At the cold wall thermal and concentration Grashof numbers reduces the Nusselt values but they increase the Nusselt values at the hot wall. The reversal consequence was attained at the hot plate. The perturbation and Runge-Kutta solutions are equal in the nonappearance of Prandtl number. The (E. Zanchini, Int. J. Heat Mass Transfer 41, 3949 (1998)). results are restored for the regular fluid. The heat transfer rate is high for nanofluid when matched with regular fluid.

Natural convection of [Formula: see text]-water nanofluid in a non-Darcian wavy porous cavity under the local thermal non-equilibrium condition

This study investigates thermal natural convective heat transfer in a nanofluid filled-non-Darcian porous and wavy-walled domain under the local thermal non-equilibrium condition. The considered cavity has corrugated and cold vertical walls and insulated horizontal walls except the heated part positioned at the bottom wall. The transport equations in their non-dimensional model are numerically solved based on the Galerkin finite-element discretization technique. The dimensionless governing parameters of the present work are the nanoparticle in volume concentration, the Darcy number, number of undulations, modified heat conductivity ratio, dimensionless heated part length, and location. Comparisons with other published theoretical and experimental results show good agreement with the present outcomes. The findings indicate that the heater length, its position, and the waves number on the side vertical walls as well as the nanoparticles concentration can be the control parameters for free convective motion and heat transport within the wavy cavity.