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The main objective of this work is to investigate viscous dissipation with thermal radiation impact on hybrid nanofluid flow past an exponentially stretching/shrinking surface along with magnetic field, and heat source/sink, slip boundary conditions. Water ( H 2 O ) is taken into account as a host fluid with copper (Cu) and alumina ( Al 2 O 3 ) as nanoparticles to form a hybrid nano liquid (Cu- H 2 O - Al 2 O 3 ). The coupled nonlinear partial differential equations are transmuted into ordinary differential equations using similarity transformations with boundary conditions and these ODEs are simplified using numerical solver, bvp4c in MATLAB. The behavior of momentum profiles, thermal profiles, coefficient of heat transfer ( Nux 1 ) and skin friction ( C f ) are explored using the pertinent parameters such as Eckert Number ( Ec 1 ), Suction Parameter ( S 1 ), Magnetic Parameter ( M 1 ), Radiation Parameter ( Nr 1 ), Stretching/Shrinking Parameter (λ ), Velocity and thermal slip Parameters ( A 1 and B 1 ), Heat source/sink Parameter ( β 1 ), variable thermal Parameter (ϵ ), thermal conductivity (K) are depicted through tables and graphs. The present simulation is more stable and convergence when compared with the existing literature, which is portrayed in the tables. The presence of dual solution is noticed for Ec 1 = 0.1, 0.11,0.12 when the critical value of λ (= λ c ) are λ c 1 = - 1.60355799, λ c 2 = - 1.60322884 and λ c 3 = - 1.6031348, respectively. The existence of the dual solution is reported due to the presence of shrinking surface and suction, further, the first solution is found to be more stable. The novelty of the current simulation includes MHD hybrid nano liquid flow stability with the impact of viscous dissipation and thermal radiation past stretching/shrinking permeable plane to fill the research gap in the existing literature. The applications of transmission of heat by stretching/shrinking surface in boundary layers is used in various fields such as polymer and material processing, biomedical engineering, heat exchangers, etc. [ABSTRACT FROM AUTHOR]

Jeffrey fluids, a subset of non-Newtonian fluids, have received substantial research attention owing to their versatile utility in industries, such as polymer processing, cosmetics, and glass manufacturing. This paper endeavors to introduce a pioneering outlook on the behavior of Jeffrey fluids by researching their intricate responses to an array of influencing factors, including slip conditions, thermal effects, magnetic fields, chemical influences, and pivotal roles in the enhancement of drug delivery systems. Jeffrey fluids hold particular significance in modeling physiological fluids found in biological systems, representing blood circulation with precision in terms of relaxation time and stress retardation. Interestingly, under specific conditions, when subjected to wall shear stress exceeding the yield strength, Jeffrey fluids transition to exhibit Newtonian fluid characteristics. Hence, we embark on a comprehensive exploration of the applicability of the Jeffrey fluid model across diverse industrial domains and its contribution to the realm of flow control. Our research focuses on the study of mixed convective Jeffrey fluid flow across an inclined vertical plate, considering the combined impacts of the Soret and Hall currents, along with slip conditions involving velocity, temperature, and concentration disparities. This intricate problem is analytically resolved through the careful use of the perturbation technique. Furthermore, the inclined angle parameter enhances the velocity profile, while the velocity slip parameter exhibits the opposite effect. Additionally, the thermal and concentration slip parameters attenuate the temperature and concentration profiles. [ABSTRACT FROM AUTHOR]

Transformer oil is used to maintain the core and winding of the transformer. The main tasks of transformer oil as an industrial oil are insulation and cooling of a transformer. In the current study, the thermophysical and thermal properties of transformer oil nanofluid with volume percentages of 0.017% and 0.56% have been experimentally investigated which improves the performance of the base fluid due to the high thermal conductivity coefficient of carbon nanotubes compared to transformer oil. Ultrasonic baths and chemically functionalizing techniques were utilized in a two-step process to create nanofluids, which were stabilized by these techniques. In a double-tube carbon steel heat exchanger, the nanofluids were employed, and the thermal characteristics of the base fluid and nanofluids were evaluated. The findings indicated that the effective thermal conductivity improves with increasing temperature and CNT concentration, reaching its maximum value at a temperature of 45 °C in a volume fraction of 0.56. Observations showed that the heat transfer coefficient rose with rising Reynolds number and volume percentage, whereas the friction factor reduced when the hot fluid flowed at an intake temperature of 80 °C compared to the nanofluid in the outer tube. The flow rates for the nanofluids were calculated to be 0.2, 0.3, 0.4 lit/s, and 0.18 lit/s for the hot fluid, respectively. As a general conclusion, carbon nanotubes have a very high potential to improve the thermal performance of transformer oils, which is a serious challenge. [ABSTRACT FROM AUTHOR]

The aim of the current effort was to analyze two-dimensional unsteady squeezing Casson fluid flow among porous channels. Flow field was impressed into uniform magnetic field affecting normal through that plate axes. The interaction on flow model into chemically reacting solute was formed over this advection–diffusion equation on that temperature dependency by that reaction rate of activation energy was studied. The Energy equation comprising thermal stratification and source terms was considered. To make the solutions on governing equations that was partial differential equations in kind, they have transformed them along ordinary differential equations to utilizing suitable comparison transformation and it is used in finite element method. This effect on sundry parameters by flow, concentration and temperature fields was considered into the use of graphic illustrations. Solutions display into improvement on that values of this magnetic parameter and Casson parameter, this velocity reduces nearby bottom plate although that indicates opposite performance into the above one. This temperature on the fluid raises into developing the two radiation parameter along the Eckert number although reduces into augmenting values by the stratification parameter. The significant data were the activation energy on chemical reaction unusually changes the solute concentration in that fluid flow. [ABSTRACT FROM AUTHOR]

CPU computes several complex algorithms at billions of cycles per second. It is acceptable to generate some heat while working at such great speed. In order to reduce the problem of high temperature, which slows down the performance of tasks, a new heat sink with convex-parabolic fins was designed to study the best heat dissipation methods to reach the cooling efficiency of the processor so that it performs all tasks without any problems. On the other hand, the new heat sink was cooled by the hybrid nanofluid, and all the equations governing the phenomenon were solved by the finite volume method, and the results were reported at Reynolds numbers and fin numbers. From the results, the cooling efficiency was improved by 74% when a large number of fins were used. Besides that, the maximum temperature of the heat sink decreases by increasing the number of convex-parabolic fins, giving the processor a cool surface to perform tasks without having to fear the problem of overheating. The results of this study can be used for the initial design of the heat sink and the improvement in the efficiency of cooling the Core I7 CPU. [ABSTRACT FROM AUTHOR]

The numerical simulation of a shell-and-tube heat exchanger (STHE) depends on a large number of computational cells. The number of computational cells increases dramatically with increasing heat transfer surfaces in heat exchangers, such as increasing the number of tubes or using dimples as modified surfaces. Computational cost is one of the critical parameters in many industrial applications for heat exchanger analysis. The present study uses the P-NTU thermal analysis method, proposes correlations to predict heat transfer inside and outside the tubes, and then analyzes the STHE with elliptical dimples. The analytical approach shows 0.8% and 9% errors for two STHEs with specified heat performance, which is entirely acceptable. Also, for the STHE with elliptical dimples, the results indicate a 40.6% increase in the heat capacity of STHE. Increasing the heat capacity of STHE by using modified surfaces such as dimples significantly reduces the dimensions and weight of STHE in industrial applications. Furthermore, the analytical method can be used for different types of dimples with different geometries and arrangements. [ABSTRACT FROM AUTHOR]

Hybrid nanofluids were popularized by heat transfer fluids into higher surface strength, dispersion and diffusion prospects related into traditional nanofluid. The novel characteristics of a single-phase hybrid nanofluid profile coincidence in studying nanoparticles mass including base fluid mass to produce solid equivalent density and addition to solid equivalent specific heat about constant pressure. On this work, flow and volumetric entropy generation and convective heat transport on Powell–Eyring hybrid nanofluid have been consider. Hybrid nanofluids attend the space through the systematic horizontal porous stretching surface. Impact on exponential space-dependent heat generation and nonlinear thermal radiation was more combined on the specified sketch. Mathematical equations about conservation of energy, mass, entropy and momentum are interpreted below acceptance on boundary layer flow of Powell–Eyring hybrid nanofluid. Comparison results were collected as conversion away from governing partial differential equations into ordinary differential equations, applying correlation variables. Finite element method was an external for finding the relative results of decreased ordinary differential equations. Numerical computing was achieved about zinc oxide–gold water (ZnO–Au/H2O) hybrid nanofluid and conventional gold water (Au–H2O) nanofluid. The notable allegation indicated to the hybrid Powell–Eyring nanofluid was best thermal conductor although related into a conventional nanofluid and pure water. Every rising on Reynolds number and Brinkman number developed into total entropy for that structure. [ABSTRACT FROM AUTHOR]

In the current investigation, hydromagnetic third grade pulsating nanofluid flow through a channel under the influence of Brownian motion, thermophoresis, radiative heat has been inspected. The influence of viscous dissipation, chemical reaction, and Ohmic heating is considered in the current investigation. The Buongiorno nanofluid model is implemented, and the analysis of entropy generation is carried out. The present investigation may be applicable in the fields of biomedical engineering, manufacturing industries as coolants, pressure surges, energy conservation, and nano-drug suspension in pharmaceuticals. The perturbation technique is employed on flow governing equations (partial differential equations (PDEs)) to convert into a set of ordinary differential equations (ODEs). The shooting process along with the support of Runge–Kutta fourth-order method is employed to solve the set of nonlinear ODEs. The impressions of dimensionless emerging physical parameters on pertinent flow variables are demonstrated by using graphical illustrations. The results portrayed that intensifying the Hartmann number, non-Newtonian, frequency, and material parameters decline the velocity of the nanofluid. Augmenting the Eckert number, Brownian motion, and thermophoresis parameter enhance the temperature whereas accelerating the radiation parameter and Hartmann number reduces the temperature. The nanoparticles concentration is enhanced for a rise in Brownian motion, while it decelerates for the higher values of Lewis number. The entropy and Bejan number are accelerated with the increment in radiation parameter. The heat and mass transfer rates are raised for augmenting the value of Brownian motion parameter. [ABSTRACT FROM AUTHOR]

A novel mathematical model for improving heat transfer using tri hybrid nanofluids is described in this paper. This study investigates the slip flow and radiative heat transfer over a moving sheet with polymer-based tri hybrid nanofluid. Under the imposed assumptions, equations governing the flow will be modeled. For nonlinear partial differential equations that cannot be solved accurately using similarity transformation, an ordinary differential equations system may be obtained. Numerical solutions to the streamlined equations will be found with the help of a BVP4C solver (MATLAB). The effects of the pertinent parameters on the velocity and temperature profiles along with the skin friction and heat transfer rates are discussed in detail through figures for both hybrid and tri hybrid nanofluid cases. It is reported that the Nusselt number, which measures the rate at which heat is transferred, is higher in tri hybrid nanofluid when compared to hybrid nanofluid flow. [ABSTRACT FROM AUTHOR]

Recently, Nanoparticles have supplied diverse challenges to several scientific issues. Nanoparticles dispersed in a variety of conventional fluids can change the flow and heat transmission properties of the fluids. The mathematical technique is used in this work to investigate the MHD water-based nanofluid flow via an upright cone. The heat and mass flux pattern is used in this mathematical model to examine MHD, viscous dissipation, radiation, chemical reactions and suction/injection processes. The finite difference approach was used to find the solution to the basic governing equations. A combination of nanofluids comprising nanoparticles including aluminum oxide (Al 2 O 3 ), silver (Ag), copper (Cu) and titanium dioxide (TiO 2 ) with a volume fraction of nanoparticles (0, 0.01, 0.02, 0.03, 0.04), viscous dissipation ( ϵ = 0.4 , 0.8 ), MHD (M = 0.5, 1.0), radiation (Rd = 0.4, 1.0, 2.0), chemical reaction ( λ = 0.2 , 2.0 ) and heat source/sink ( Δ = - 3 , - 2 , 0.5 , 1 ). The mathematical findings of velocity, temperature, concentration, skin friction, heat transfer rate as well as Sherwood number distributions are analyzed diagrammatically using non-dimensional flow parameters. It has been discovered that by increasing the value of the radiation parameter, velocity and temperature profiles enhance. The production of safe, high-quality products for consumers across the world depends on vertical cone mixers, from food to medicine, household cleansers to personal hygiene products. Every vertical cone mixer type we provide was especially developed to meet the demands of industry. As the mixer warms up on the slanted surface of the cone while vertical cone mixers are being utilized, the effectiveness of the grinding may be felt. The temperature is transferred along the cone's slant surface as a consequence of the mixture being mixed quickly and repeatedly. This study describes the heat transmission in these events and their parametric properties. The heated cone's temperature is then convective to its surroundings. [ABSTRACT FROM AUTHOR]

The energy transport enhancement is a topical problem for many engineering applications. One of the possible solutions to this problem is an improvement of the heat transfer surface. The present investigation is devoted to numerical simulation regarding turbulent forced convective energy transport inside a curved channel under the isothermal heating from the upper wavy wall and cooling from the inlet section. The governing partial differential equations written using the Reynolds-averaged Navier-Stokes formulation including the standard k - ε approach have been solved numerically by the finite-element procedure. Impacts of the Reynolds number, undulations number and undulations amplitude toward fluid motion and energy transport have been scrutinized. With the undulations number, a significant energy carrier condensation has been detected. [ABSTRACT FROM AUTHOR]

This study examines the magnetohydrodynamic flow of hybrid silver-alumina (Ag-Al 2 O 3 )/water nanofluid within a corrugated trapezoidal cavity that contains a heat-generating rotating solid cylinder. The hybrid nanofluid flow and convective heat transfer are modelled using a single-phase approach. The governing equations for fluid flow and convective heat transfer are solved using the penalty finite element method. The finite element algorithm was validated against previously published work, and it was found to be in good agreement with the existing literature. We investigate the effects of the Ag and Al 2 O 3 nanoparticle diameters and the radius of the heat-generating solid cylinder on streamlines, isotherms and average Nusselt number. The results of this study reveal that the flow circulation regions near the rotating cylinder are enhanced with increased nanoparticle diameters and cylinder radius. Moreover, the nanofluid temperature and heat transfer rate are increased with reduced nanoparticle diameters and increased cylinder radius. [ABSTRACT FROM AUTHOR]

The present work elucidates the hydrothermal characteristics within a non-Darcian porous complex wavy enclosure saturated with Al 2 O 3 –Cu– H 2 O hybrid nanofluid considering a uniform magnetic field. The left sidewall of the enclosure is wavy and heated isothermally, whereas the other sidewall is maintained at ambient temperature, all other walls are insulated. The Forchheimer–Brinkman-extended Darcy model is implemented to analyze the flow through porous media. The dimensionless transport equations are numerically solved following the finite volume-based in-house computational code with successive staggered non-uniform mesh distribution. The hydrothermal behaviors are investigated meticulously changing the dimensionless variables like undulation amplitude (λ ), Hartmann number (Ha), Darcy number (Da), and modified-Rayleigh number ( Ra m ). The remarkable results reveal that enhancing the heating surface area by heightening the amplitude of the undulation always leads to higher heat transfer, but does not always favor the growth of the flow strength. The heightening of the flow strength with amplitude is noted for higher Ra m only. The flow intensity, as well as heat transfer, increases with the growing Ra m . The same decreases with increasing Da and Ha. Local distribution of heat transfer characteristics shows complex behavior depending on the amplitude of the undulations and associated dimensionless numbers. [ABSTRACT FROM AUTHOR]

A numerical study was conducted to determine the impact of MHD on mixed convection of a Cu-water nanofluid in a horizontal channel attached to two open enclosures filled with a porous material is implemented in this paper. Uniform heat is supplied on the base of the two enclosures while the other walls are considered adiabatic. The finite element method has been utilized in this study to solve the considered equations and other numerical simulations that needed to be validated, assessed with previous papers to ensure that the model works correctly. Furthermore, this study considers a range of each of the Reynolds number (Re = 25, 50, 100, 150, 200), Richardson number (Ri = 0.1, 1, 3, 5, 8, 10) and the Hartmann number (Ha = 0, 5, 10, 15, 30, 50) at a constant volume fraction ( φ = 0.08) and porous media properties (Da = 10-2, and ε = 0.7). The results stated that the strength of the streamlines, isotherms, and the average Nusselt number (Nu avg ) increases with increasing values of the Richardson and Reynolds numbers while they decrease upon increasing the Hartmann number. The result shows that no big difference between cases 2 and 3, and the maximum enhancement in Nu avg is 9.84% in case 2 compared with case 1 at Re = 200, Ri = 1, and Ha = 0. [ABSTRACT FROM AUTHOR]

In this study, natural laminar convection of Al 2 O 3 /water nanofluid in a cavity slightly different from shaped H was investigated using the monophasic model. The various parameters of this flow were determined numerically using CFD-Fluent software using the finite-volume method by introducing Boussinesq approximation. The analysis is carried out for three values of the Rayleigh number (10 5 ; 2.3 · 10 5 and 3.072 · 10 5) and for three values of the form factor defined for this enclosure (0.2; 0.3 and 0.4). The impact of Rayleigh number, nanofluid concentration and cavity form factor on dynamic and thermal structure of the flow was analyzed. The results are shown in form of streamlines, isotherms, and profiles of velocity, temperature, and Nusselt number. Nusselt number rises with increasing Rayleigh number and nanofluid concentration and decreases with the form factor of the cavity. This study is well developed relative to those carried out before. With using Al 2 O 3 nanofluid, the heat transfer is improved because its thermal conductivity is increased compared to that of the base fluid. Finally, to predict heat transfer inside cavity, correlations for the Nusselt number were proposed for each form factor of the cavity. These correlations are rarely presented in this type of study. [ABSTRACT FROM AUTHOR]

A nanofluid flow under the influence of magnetic field with heat generation/absorption is considered in the cooling of electronic systems, nuclear reactors and physical phenomena such as geology. For the first time, in the present work, natural convection heat transfer in a two-dimensional enclosure with three types of wall shapes filled with a cu-water nanofluid in terms of the effect of Brownian motion of nanoparticles with heat generation/absorption and in the presence of a magnetic field is investigated by using the Lattice Boltzmann Method (LBM). The left vertical wall of the enclosure is examined in two modes: constant temperature heating and linear temperature heating and the cold wall of the enclosure in three different forms (a) diagonal, (b) curved and (c) smooth. The effect of parameters such as the Hartmann number, nanoparticle volume fraction, heat generation/absorption coefficient, cold wall shape and the type of wall heating on the nature of flow and heat transfer is investigated. The results of the authors' research were validated with other sources, and the accuracy of the outputs was ensured. The outcomes of research show that in all instances, increasing the strength of the magnetic field and the heat generation/absorption coefficient decrease the average Nusselt number. In addition, the effect of Hartmann number in various states is different. The highest heat transfer also occurs when the vertical wall has a constant temperature. In this case, the average Nusselt number is about 35% higher on average. The effect of the magnetic field is greater when the cold wall is smooth. By keeping all the parameters constant, the diagonal wall design increases the average Nusselt number by an average of about 30%. The effect of adding nanoparticles to the base fluid on decreasing or increasing the average Nusselt number depends on the Hartmann number and the heat generation/absorption coefficient. Using this numerical simulation, a comprehensive view on the optimal design of heat transfer from equipment can be obtained. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid computational fluid dynamics technique is proposed to study turbulent flow and conjugate heat transfer patterns. A typical shaped room with a radiant heating panel is considered. The mesoscopic lattice Boltzmann method coupled with the finite difference solution of macroscopic energy equation is used to compute the thermal and flow fields. To describe the radiant flux distribution along the solid–fluid interfaces, the Lambert law is implemented. An in-house code written in MatLab is validated against direct numerical simulation data obtained for a Rayleigh number up to 1011. A computational study is conducted when varying the Rayleigh number, heat flux density, radiant panel length, physical properties of the enclosure and external heat transfer coefficients with constant walls thickness and the ambient temperature. It is found that the air temperature is decreased in the room as the Rayleigh number is raised. The panel length is found to drastically affect the thermal field. However, the flow structure is altered insignificantly. The stagnant zone of air is formed at the bottom corners with low values of heat fluxes. [ABSTRACT FROM AUTHOR]

This study employs a numerical solution approach to examine the impacts of viscous dissipative, MHD, among various nanofluid flows across an up straight cone with iso-thermal surface velocity and temperature. After being converted into dimensionless form, the flow field equation is numerically evaluated using an outstanding finite difference approach. Our experiment used different types of nanofluids (Cu, Al2O3, TiO2 and Ag) and volume fractions (0, 0.01, 0.02, 0.03, 0.04) to detect differences in heat transfer occurrence depending on temperature and velocity. Graphs have been used to show a parametric analysis for various flow field features. [ABSTRACT FROM AUTHOR]

The present study analyzes the forced convective boundary layer flow of viscous incompressible time-established fluid. The base fluid containing water-based nanoparticles and gyrotactic microbes. The flat surface is considered with leading-edge accretion (or) ablation. Characteristics of flow are explored by the impacts of thermal radiation and constructive/destructive chemical reaction. The present flow problem is formed with the partial differential equations, and transformed nonlinear boundary value problems are solved mathematically by the finite difference with the collocation method. There is a good correlation between present work and previous work. Results of selected parameters on velocity, temperature, nanoparticles volume fraction, and microbe density function are discovered. Skin friction, heat transport, mass transfer, and microbes transfer rates are tabular. Efforts of the current work rise in progressive microflow devices to bio-modified nanomaterial dispensation. [ABSTRACT FROM AUTHOR]

The study investigates the approach to enhance the thermal management of battery cell module by attaching number of inverted triangular cavity to its casing. A sinusoidal heating is considered to battery cell module or a left wall of the cavity. The sinusoidal heated region is considered to be a function of amplitude ratio. The objective is to transfer the heat from module using natural convection process. The enhanced heat transfer is possible by adopting hybrid nanofluid in a triangular cavity due to its improved thermophysical properties. Thus, the investigation on natural convection heat transfer, fluid flow, and irreversibility within an inverted right-angled triangular porous cavity is conducted. Numerical results are obtained through an own-house FORTRAN coding, that uses the streamfunction–vorticity algorithm. The numerical results are derived for various values with Rayleigh number (103-106\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${10}^{3}-{10}^{6}$$\end{document}), Darcy number (10-5-10-1)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${10}^{-5}-{10}^{-1})$$\end{document}, Hartmann number (0-50)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0-50)$$\end{document}, amplitude ratio (0.0-0.9\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0.0-0.9$$\end{document}) and volume fraction of nanoparticles (0.01-0.04\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0.01-0.04$$\end{document}), respectively. The irreversibility and flow results are compared with the various hybrid nanofluids. The study indicates that opting inverted right-angled triangular cavity rather than a square shape leads to an improvement in heat transfer. Accordingly, this inverted right-angled triangular cavity natural convective cooling can be considered as optimum design with the battery cell module for improved thermal management.Graphical abstract: The study investigates the approach to enhance the thermal management of battery cell module by attaching number of inverted triangular cavity to its casing. A sinusoidal heating is considered to battery cell module or a left wall of the cavity. The sinusoidal heated region is considered to be a function of amplitude ratio. The objective is to transfer the heat from module using natural convection process. The enhanced heat transfer is possible by adopting hybrid nanofluid in a triangular cavity due to its improved thermophysical properties. Thus, the investigation on natural convection heat transfer, fluid flow, and irreversibility within an inverted right-angled triangular porous cavity is conducted. Numerical results are obtained through an own-house FORTRAN coding, that uses the streamfunction–vorticity algorithm. The numerical results are derived for various values with Rayleigh number (103-106\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${10}^{3}-{10}^{6}$$\end{document}), Darcy number (10-5-10-1)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${10}^{-5}-{10}^{-1})$$\end{document}, Hartmann number (0-50)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0-50)$$\end{document}, amplitude ratio (0.0-0.9\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0.0-0.9$$\end{document}) and volume fraction of nanoparticles (0.01-0.04\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$0.01-0.04$$\end{document}), respectively. The irreversibility and flow results are compared with the various hybrid nanofluids. The study indicates that opting inverted right-angled triangular cavity rather than a square shape leads to an improvement in heat transfer. Accordingly, this inverted right-angled triangular cavity natural convective cooling can be considered as optimum design with the battery cell module for improved thermal management. [ABSTRACT FROM AUTHOR]

This paper examines the capability of hybrid lattice Boltzmann method to simulate developed turbulent buoyancy-driven flows in closed rectangular cavities. The two-relaxation time mesoscopic lattice Boltzmann method is used as a fluid dynamics solver, whereas the thermal behavior is described in terms of the macroscopic energy equation. Numerical simulation is performed for air-filled square and tall cavities in a range of the Rayleigh number 10 9 ≤ R a ≤ 10 11 . An in-house numerical code is developed in this study and successfully validated against up-to-date numerical and experimental data of other researches. It is found that the proposed hybrid approach accurately predicts the location of thermal plumes at the isothermal walls despite an insignificant error in the heat transfer rate with the R a ≥ 3 · 10 10 . [ABSTRACT FROM AUTHOR]

Exergy efficiency, Nusselt number, friction factor, pressure drop, thermal and frictional entropy generation of water-based nanodiamond + Fe3O4 nanofluid flow in a tube and with various coiled wire inserts have been studied experimentally under turbulent and constant heat flux boundary conditions. The experiments were conducted in the Reynolds number range from 2000 to 22,000, particle concentrations of 0.05%, 0.1% and 0.2% and coiled wire inserts of different p / d values of 3.67, 2.34 and 1.00, respectively. Results indicate that at 0.2% vol. and Reynolds number of 20,095, without coiled wire inserts, the heat transfer coefficient, Nusselt number, friction factor, pressure drop and pumping power are enhanced to 44.36%, 29.55%, 11.1%, 29.58% and 39.49% over the base fluid data. Similarly, at 0.2% vol. and Reynolds number of 20,095, with coiled wire inserts of p / d = 1, the heat transfer coefficient, Nusselt number, friction factor, pressure drop and pumping power are further enhanced to 107.19%, 66.36%, 38.84, 64.44% and 76.54% over the base fluid data without inserts. The thermal entropy generation is decreased to 30.80% and it is further decreased to 46.34% at 0.2% vol. and Reynolds number of 20,095 with coiled wire inserts of p / d = 1. The exergy efficiency of water is 18.95%, and it is increased to 24.06% for 0.2% vol. and it is further increased to 51.85% for 0.2% vol. and Reynolds number of 20,095 with coiled wire inserts of p / d = 1. The study indicates that the hybrid nanofluids with coiled wire inserts are guaranteed choice for augmenting the exergy efficiency of flow through tube. [ABSTRACT FROM AUTHOR]

This paper examines the capability of hybrid lattice Boltzmann method to simulate developed turbulent buoyancy-driven flows in closed rectangular cavities. The two-relaxation time mesoscopic lattice Boltzmann method is used as a fluid dynamics solver, whereas the thermal behavior is described in terms of the macroscopic energy equation. Numerical simulation is performed for air-filled square and tall cavities in a range of the Rayleigh number 10 9 ≤ R a ≤ 10 11 . An in-house numerical code is developed in this study and successfully validated against up-to-date numerical and experimental data of other researches. It is found that the proposed hybrid approach accurately predicts the location of thermal plumes at the isothermal walls despite an insignificant error in the heat transfer rate with the R a ≥ 3 · 10 10 . [ABSTRACT FROM AUTHOR]

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 ( C u + Al 2 O 3 + water ) 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 ( F , G , H ), 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 ( G (ξ , η) ) is dropping for heightening heat source (Q ) surface friction remarkably declines with the outlying magnetic field ( St ); thermal transport confronts drastic abatement under radiation ( R 1 ), and St ; the characteristics Reynolds and Brinkman numbers promote entropy. Furthermore, the bounding surface acts as a strong source of S G -production. Summarizations are listed at the end to quantify percentage variations. [ABSTRACT FROM AUTHOR]

In this study, a theoretical analysis is performed to address the features of heat and mass transfer phenomena of two-dimensional viscous fluid flow of Oldroyd-B nanofluid over a vertical stretched sheet which contains gyrotactic microorganisms by considering the mixed convection and inclined magnetic field effects. The induced flow features have been considered by triple stratified medium. Additionally thermal radiation effect is included in the energy equation. To make the present study reasonably worthy, impact of Joule heating and heat sink/source is also considered. By applying the defined similarity transformations physical flow system is reduced to nonlinear system. Thereafter, numerical solution with desired accuracy is obtained with the help of RKF-45 method. Graphical representation is done for the flow controlling parameters involved in this analysis. Main observations of the present study are velocity distribution declined with a relaxation time and thermal stratification parameter and motile density profile is promoted by increasing bioconvection Rayleigh number and buoyancy ratio. These results are reasonable correlated with the previous findings reported in literature. Based on these scientific reports, this work is relevant to bio-inspired nanofluid-enhanced fuel cells and nanomaterials fabrication processes. [ABSTRACT FROM AUTHOR]

Exploiting the impact of Lorentz force and convective heating boundary on second-grade nanofluid flow alongside a Riga pattern is the main objective of the present work. Modelling of the present work is done through Grinberg term and a Lorentz force applied parallel to the wall of a Riga plate. The nanoparticles fraction on the solid surface of Riga pattern maintained a strong retardation because of zero mass flux. Theories of Cattaneo–Christov heat flux and generalized Fick's relations are employed by following the modern aspects of heat and mass transportations. In the current study, additional features of thermal radiation are also included in the energy equation in terms of linear expressions. In order to make the analysis more worthy, effect of chemical reaction is also included. By applying the suitable variables, constituted problem is converted into dimensionless form. Solution of the problem with desired accuracy is obtained by utilizing popular method called Runge–Kutta–Fehlberg. The graphical representations are used to illustrate the flow controlling parameters involved by their attractive physical consequences. Velocity distribution is observed for the increase with the second-grade parameter. Further, an improved nanoparticles temperature distribution is observed with the increase in radiation parameter and Biot number. Additionally, the distribution of the concentration of nanoparticles increases with increase in values of the thermophoretic parameter. Based on the scientific calculations obtained, it is established that the reported results may play a useful role in production processes and in the improvement of energy and thermal resources. [ABSTRACT FROM AUTHOR]

The impact of wall movements in different directions on mixed convection flow and thermal performance in a wavy chamber is reported. The wavy wall of the chamber is heated non-uniformly, and the upper wall is kept at a constant cold temperature, while the vertical walls of the chamber are adiabatic. Four different cases, namely Case-1, Case-2, Case-3 and Case-4, are considered on the basis of multi-directional movements of the walls of the chamber. Mathematical model of the flow physics consists of the Navier–Stokes (N-S) equations in streamfunction (ψ ) —vorticity (ζ ) formulation including the energy transport equations which are solved by higher-order compact (HOC) scheme on curvilinear grids Pandit SK, Chattopadhyay A.(Comput Math Appl 74(6):1414–34 2017) [45]. It is found that the fluid flow and thermal performance are both influenced by the direction of moving lids and the undulations of the wavy bottom surface of the chamber. Optimum thermal performance is noticed when the wavy bottom surface of the chamber is employed with one undulation at low Richardson number (Ri). Moreover, for R i = 0.01 , Case-2, in which the upper lid is moving in left direction and the left lid is moving in upward direction, gives better heat transfer rate with maximum value of average Nusselt number for one undulation. Furthermore, it is noticed that among all the cases, the cases (Case-2 and Case-4) in which upper lid is moving in left direction produce minimum entropy generation for every undulations of the wavy surface with each of the Ri values. So, on the basis of better heat transfer rate and the minimum entropy generation, Case-2 and Case-4 may be recommended as optimum configurations. [ABSTRACT FROM AUTHOR]

Single-phase nanofluid heat and mass transfer futures over swirling cylinder with the impact of Cattaneo–Christov heat flux and slip effects is studied in this analysis. The effects thermophoresis, thermal radiation, Brownian motion and chemical reaction are also considered and the motion of the fluid is because of the torsional motion of the cylinder and these parameters. Suitable similarity transformations are implemented to simplify the fluid equations from partial differential equations to ordinary differential equations. The most powerful finite element technique is applied to solve the subsequent equations along with boundary conditions. Variations in the scatterings of swirling velocity, axial velocity, concentration and temperature with several pertinent parameters are portrayed through plots. Nusselt number, both components of skin friction coefficient and Sherwood number values are also examined in detail and are revealed in tables. Temperature sketches diminish in nanofluid region with rising values of heat flux relaxation number. It is detected that the nanofluids temperature deteriorates with augmenting values of temperature slip parameter. The present numerical code is validated with existing literature. [ABSTRACT FROM AUTHOR]

A hydromagnetic transverse flow of an Oldroyd-B-type liquid with a heat flux of the Cattaneo–Christov model with variable thickness has been analyzed. Consider additional impacts of thermal conductivity as well as heat generation. Governing equations were transmitted into a set of nonlinear ordinary differential equations using similarity conversion, and then, numerical solution was evaluated using the procedure Runge–Kutta–Fehlberg. The physical response related to velocity and temperature is investigated computationally. The outcomes also show that the momentum boundary-layer thickness increases the values of magnetic field strength, but the reverse trend is observed for the thermal boundary layer. Impacts of retardation and relaxation time effects are quite the opposite of the temperature field. The obtained computations are useful in transport phenomena which are involving hydromagnetic rheological fluids. [ABSTRACT FROM AUTHOR]

The ultimate goal of the present review paper is to summarize and discuss the findings of the most recently published literature on natural convection of nanofluids in various enclosures. The review covers five different geometries of enclosures: square, circular, triangular, trapezoidal, and unconventional geometries. The core findings of the reviewed papers are summarized and tabulated in a table. Moreover, the relation between the thermophysical properties and the way they affect each other is demonstrated for different geometries of enclosures. Various numerical methods, such as finite difference, finite volume, and finite element methods, as well as different microscopic models, such as single-phase and two-phase models, are considered in this review. [ABSTRACT FROM AUTHOR]

Two-dimensional forced convective steady boundary layer flow of non-Newtonian Eyring–Powell nanofluid over a moving plate in a porous medium in the presence of a parallel free-stream is investigated. The governing coupled non-linear partial differential equations (PDEs) along with boundary conditions are transformed into a set of non-linear coupled ordinary differential equations (ODEs) by using appropriate transformations. The obtained non-linear ODEs with modified boundary conditions are converted into a system of first-order ODEs which are solved using the classical and efficient shooting method. Dual solutions for velocity, temperature and nanoparticle concentration distributions for Eying–Powell fluids similar to Newtonian fluid in some special flow situations are obtained, when the plate and free-stream are moving along mutually opposite directions. The stability analysis of the obtained solutions is performed and it is found that the upper branch solutions are physically stable, while lower branch solutions are unstable. The impacts of different dimensionless physical parameters on velocity, temperature and nanoparticle concentration are reported in the form of graphs and tables. An important result is obtained and it reveals that the 'dual solutions' character has been destroyed if resistance due to the porous medium is raised up to a definite level (i.e., permeability parameter K > 0.07979 ), though the range of existence of unique solution becomes larger with further increase of resistance due to porous medium. It is also observed that heat transfer rate diminishes with increasing thermophoresis parameter, Brownian diffusion parameter and Lewis number in all the cases, whereas mass transfer rate enhances with thermophoresis parameter (for dual solutions), Brownian diffusion parameter (for unique solutions) and Lewis number (for unique solutions). Further, skin-friction coefficient, i.e., the surface drag force, increases with permeability parameter, suction/injection parameter and decreases with Eyring–Powell fluid parameter. Also, increments in permeability parameter and the suction/injection parameter lead to the delay in the boundary layer separation. The critical values of velocity ratio parameter beyond which the boundary layer separation appears are − 0.5476432, − 0.5987132, − 0.704862, − 0.816944, − 0.9365732, − 0.96179102, − 1.057104, − 1.062004, − 1.09222, − 1.115824, − 1.193413, − 1.591023 and − 1.898366 for K = 0 , 0.01, 0.03, 0.05, 0.07, 0.074, 0.08, 0.082, 0.085, 0.09, 0.1, 0.15 and 0.2, respectively. [ABSTRACT FROM AUTHOR]

Modeling and computations are performed to study the ND-Co3O4/EG hybrid nanoliquid mixed convective flow past a vertical porous cylinder. The flow analysis and formulation are given accounting for slip effects and homogeneous-heterogeneous reaction impacts. The governing complex equations formed with prescribed boundary conditions are simplified into self-similar equations through the use of suitable transformations. The numerical solutions of the drag coefficient, Nusselt number, liquid velocity, liquid temperature, and the liquid concentration are explored through graphs with the setting of pertaining parameter values. From the results, it is noticed that an ND-Co3O4/EG nanofluid plays a more impressive role in the process of energy transfer than a Co3O4/EG nanofluid. Further, it is found that the heterogeneous reaction parameter decreases the concentration whereas multiple slips enhance the temperature. [ABSTRACT FROM AUTHOR]

Arid regions around the world are characterized by hard summer and winter seasons, which leads to thermal discomfort. The southwest of Algeria is classified as an arid region, where the temperature in the summer season passes sometimes 50 °C in the shade and reaches negative values in the winter season. In addition, the yearly relative humidity is below 50%. The hard thermal and hygrometric situation requires actions to fulfill the thermal comfort requirements. Air-conditioning systems are a solution, but at the same time, they are responsible for a big amount of energy consumption in the building sector. In the present paper, an experimental investigation is conducted on the performance of a coupled system: earth-to-air heat exchanger and a solar chimney. The main purpose is to reduce costs and maximize the direct effect between the two techniques. The obtained results showed that the new system was able to create two main thermal regimes in the same day. The first one is a 'heating' by increasing the outlet air temperature passing through the buried pipe and solar chimney to reach a maximum gain of 14 °C in day 3. The second thermal regime is the 'cooling' that is made by reducing the air temperature at the EAHE outlet by 11.6 °C on day 5. It is also observed that the system increases the outlet air relative humidity by 46% due to the condensation phenomena and reduces it sometimes by 45%. The recent model made of the two techniques was able to produce between 3 and 20 Watts of heating/cooling capacity at the outlet of the system. [ABSTRACT FROM AUTHOR]

The current problem is performed to analyze the heatline visualization of the mixed convection mechanism and heat transfer in a double lid-driven square cavity having a heated wavy bottom surface. The moving vertical surfaces are under adiabatic conditions, and the top surface is at a cold temperature. The finite element method is employed to determine the dimensionless governing equations controlled by specific boundary conditions. The implications of the Reynolds number ( 10 ≤ Re ≤ 500 ), the directions of the constant moving wall ( λ l = ± 1 , λ r = ± 1 ), Richardson number ( 0.01 ≤ Ri ≤ 100 ), Prandtl number ( 0.015 ≤ Pr ≤ 10 ) and the number of oscillations ( 1 ≤ N ≤ 4 ) are visualized by the streamlines, isotherms and the heatlines. The same direction of lid-driven cases leads to two primary circulation cells. The Richardson number increases as it imposes the increment of the vertical temperature gradient. At a high Prandtl number, the convection mode of heat transfer is fully established, and heat conduction occurs at a low Prandtl number. Moreover, the number of oscillations has the most significant direct impact on the streamlines and the temperature distributions compared to the flat surface. Higher Reynolds and Prandtl numbers result in an increment in the local and average Nusselt numbers. The result shows that one oscillation of the wavy surface with a low Richardson number yields to have an optimum heat transfer in the cavity. [ABSTRACT FROM AUTHOR]

The small-amplitude oscillatory compression is used in many micromachines to measure various properties of molten polymers and has several advantages over rotational devices due to a less sophisticated mechanism and the lower cost. In this article, an oscillatory squeezing flow of GO–MoS2 hybrid nanofluid mixed in C2H6O2–H2O is considered over a variably hot stretching elastic membrane. The two-dimensional unsteady heat convection problem is modeled by the Navier–Stokes and the energy conservation equations. The normalized governing equations are solved with an advanced fourth-order numerical finite-difference scheme. Various characteristics of the flow and the heat transfer phenomena, such as the velocity and the temperature profiles, the skin-friction drag and the heat transfer rate at lower wall, are calculated and analyzed through several graphs and tables. The results reveal that the forward and backward flow strongly depends upon the amplitude of compression. A 30% increase in the amplitude of compression oscillation results in 109% increase of heat transfer rate from fluid to stretching membrane without altering the frictional drag significantly. Further, adding 8% concentration of GO–MoS2 hybrid nanofluid enhances the heat transfer rate from fluid to membrane by 21.4%. Moreover, as the Strouhal number increases from 1 to 6 the heat transfer rate from fluid to membrane increases up to 77.6%. [ABSTRACT FROM AUTHOR]

The present examination is considered to discuss the steady, two-dimensional flow of heat and mass transfer of nanofluid flow along with the variable suction under the influence of heat source/sink alongside the viscous dissipation. Because of the stretchable surface, flow is generated. Spectral relaxation technique is used to acquire the numerical solution for the altered nonlinear group of differential equations. Thereafter, outcomes which were obtained from the above numerical technique are validated by comparing with the available outcomes in the existing literature and also with MATLAB inbuilt solver bvp4c. All the acquired results from the above numerical system are shown through graphs and tables to discuss different resulting parameters related to the present analysis. The range of the physical parameters is taken as - 0.1 ≤ f w ≤ 0.5 , 0.1 ≤ N t ≤ 0.7 , 0.1 ≤ N b ≤ 0.7 , 0 ≤ E c ≤ 1.2 , - 0.5 ≤ Q ≤ 0.5 , 1 ≤ P r ≤ 10 , 1 ≤ L e ≤ 5. The main findings are as follows: For the effect of suction parameter, the profiles of velocity, temperature and mass friction are decreased, and the coefficient of skin friction and Nusselt number is declined for the impact of thermophoresis parameter. [ABSTRACT FROM AUTHOR]

The entropy production and mixed convection within a trapezoidal nanofluid-filled cavity having a localised solid cylinder is numerically examined using the finite element technique. The top horizontal surface moving at a uniform velocity is kept at a cold temperature, while the bottom horizontal surface is thermally activated. The remaining surfaces are maintained adiabatic. Water-based nanofluids ( Al 2 O 3 nanoparticles) are used in this study, and the Boussinesq approximation applies. The influence of the Reynolds number, Richardson number, nanoparticles volume fraction, dimensionless radius and location of the solid cylinder on the streamlines, isotherms and isentropic are examined. The results show that the solid cylinder's size and location are significant control parameters for optimising the heat transfer and the Bejan number inside the trapezoidal cavity. Furthermore, the maximum average Nusselt numbers are obtained for high R values, where the average Nusselt number is increased by 30% when R is raised from 0 to 0.25. [ABSTRACT FROM AUTHOR]

The study of fluid flows in a cavity and their effect on thermal performance in heat transporting and entropy generation are found in many heating and cooling engineering applications such as energy storage geothermal reservoirs, boilers, solar collectors, underground water flow, lakes, nuclear reactors. This paper presents a comprehensive review of the recent numerical and experimental studies on both heat transfer and entropy generation and their applications in cavities. The effect of the fluid thermal properties, the cavity configuration, the boundary, and initial conditions, the magnetic field, the thermal source discretion, and other geometrical and physical parameters on heat transfer and entropy generation are discussed. This study also presents the effect of several important dimensionless parameters such as the Reynolds, Richardson, Grashof, Rayleigh, Darcy, Hartmann, and Prandtl numbers on both natural and combined convection heat transfer mechanisms in cavities. [ABSTRACT FROM AUTHOR]

In this examination, a mathematical model is developed for Darcy free convection with reference to an isothermal vertical cone along with fixed apex half angle, pointing downward in a nanofluid-saturated porous medium. The aim of this methodology is to offer another sort of primary fluid containing nanoparticles and gyrotactic microorganism's consistence of permeable medium, chemical reaction alongside convective boundary circumstance. The model presents design rules for improvement of imperative fabrication of fertilizer and polymer substance. The present model includes the gyrotactic microorganisms alongside nanoparticles, and cone is dependent on concentration of nanoparticles as well as density of motile microorganisms. Two important impacts Brownian motion as well as thermophoresis are also included in the present model for nanofluids. Reduced system of nonlinear differential equations is derived from governing partial differential of the present flow by using usual transformations along with Oberbeck–Boussinesq approximation. After that, this reduced system is solved numerically with the use of fifth-order Runge–Kutta method in conjunction with the shooting technique. Relevant outcomes are exhibited graphically and talked about quantitatively as for variety in the flow controlling parameters related to the present analysis. Mainly, the observations are bioconvection parameters will in general improve the concentration of the rescaled density of microorganisms and nanoparticles volume fraction and dimensionless motile microorganisms reduce with strong chemical reactions. [ABSTRACT FROM AUTHOR]

In the current study, magnetohydrodynamics mixed convective flow of Ag–MgO/water hybrid nanofluid in a triangular shaped partitioned cavity involving a porous layer is numerically investigated by using the finite element method. In the numerical simulation, various effects of pertinent parameters such as Richardson number (between 0.01 and 100), Hartmann number (between 0 and 60), magnetic field inclination angle (between 0 and 90), Darcy number (between 10 - 4 and 5 × 10 - 2 ), location of the vertex of triangular porous region (between 0.2 and 0.8 H) and hybrid nanoparticle solid volume fraction ( ϕ 1 between 0 and 0.01, ϕ 2 between 0 and 0.01) on the fluid flow and convective heat transfer features are examined. It was observed that a large vortex is established below the main vortex near the upper wall for the lowest value Ri number. At the highest magnetic field strength, multi-recirculation flow pattern is seen in the right bottom corner. The average heat transfer enhances with higher values of permeability of the porous medium, magnetic field inclination angle, distance of the porous layer vertex from the hot wall and solid nanoparticle volume fraction of each particles in the hybrid nanofluid. The impact is reverse for higher values of Richardson number and Hartmann number. In the current work, significant changes in the average Nusselt number are obtained by varying the location of the porous medium. The triangular shaped porous compound can be used as an excellent tool for convective heat transfer control. [ABSTRACT FROM AUTHOR]

This paper aims to understand the characteristics of heat transfer and flow by natural convection of Al2O3–Cu/water-based hybrid nanofluid-filled square domain containing various configurations of a corrugated conducting solid under a horizontal magnetic field. The basic equations in their non-dimensional form are numerically solved using the finite volume discretization technique. The Corcione correlations are utilized to estimate the overall heat conductivity and overall viscosity of the hybrid nanoliquid when the nanoparticle's Brownian motion is taken into account. The dependency of different governing factors of the investigation, namely volume fraction of the combined nanoparticles, Rayleigh and Hartmann numbers, undulation number, undulation amplitude and the fluid/solid heat conductivity ratio, on thermohydrodynamic characteristics are delineated. Results stated that the maximum heat transmission rate was obtained for weak values of Hartmann, undulation number, undulation amplitude and high values of Rayleigh and nanoparticles volumic fraction. In addition, the fluid/solid heat conductivity ratio parameter was found to boost the heat transfer at weak Rayleigh while reducing it at high Rayleigh. [ABSTRACT FROM AUTHOR]

The present work is dedicated to understanding the natural convective flow mechanism and heat exchange under magnetic field within a concentric circular annulus between a heat-generating conductive internal cylinder and an isothermally cold external cylinder filled with a CNTs-water-based nanoliquid. The free convective flow is generated by the temperature gradient created between the inner heat-generating solid cylinder and the outer cold cylinder. The flow equations in their dimensionless form are numerically solved via the technique of finite volume. The dependency of various factors and their interrelationships affecting the thermo-hydrodynamic behavior and heat exchange rate within the system has been delineated. The findings of this study emphasize the role of the considered control parameters with regards to the hydro-thermal characteristics and the heat exchange rate within the annulus. [ABSTRACT FROM AUTHOR]

The present work aims to examine the thermal efficacy of half-sinusoidal nonuniform heating at different spatial frequencies for a porous natural convection system using Cu–Al2O3/water hybrid nanofluid and magnetic field. The system is presented utilizing a classical square enclosure heated nonuniformly at the bottom wall, and the sidewalls are allowed to exchange heat with the surroundings. The Brinkman–Forchheimer–Darcy model is adopted catering other additional terms for buoyant force and magnetic field. The governing equations are transformed into nondimensional forms and then solved numerically using a finite volume-based computing code. The importance and fundamental flow physics are explored in terms of the pertinent parameters such as the amplitude (I) and spatial frequency (f) of half-sinusoidal heating, Darcy–Rayleigh number (Ram), volume fraction of hybrid nanoparticles (ϕ ), and Hartmann number (Ha). The flow structure and heat transfer characteristics are analyzed and presented utilizing heatlines, streamlines and isotherms and average Nusselt number. The results show that the use of half-sinusoidal nonuniform heating along with hybrid nanofluid can be a viable method for enhancement and control of the overall thermal performance. The study indicates that half-sinusoidal heating could be a promising technique for better heat transfer even in the presence of flow dampening effects like porous media and magnetic fields. [ABSTRACT FROM AUTHOR]

The intent of this study is to demonstrate an approach for augmenting heat transfer through porous media subjected to nonuniform heating during the magnetohydrodynamic flow of a hybrid nanofluid of Cu–Al2O3/water. The efficacy of such a heating technique is examined utilizing a classical flow geometry consisting of a square cavity. The heating is made at the bottom following a half-sinusoidal function of different frequencies, along with the presence of a uniform magnetic field. The thermal conditions of the cavity, particularly at the bottom wall, drive thermo-hydrodynamics and associated heat transfer. Furthermore, the addition of different types of nanoparticles to the base liquid in order to boost the thermal performance of conventional fluids and mono-nanofluids is a current technique. The coupled nonlinear governing equations are solved numerically in dimensionless forms adapting the finite volume approach, the Brinkman–Forchheimer–Darcy model, local thermal equilibrium and single-phase model. The study is conducted for wide ranges of parametric impacts to analyze global heat transfer performance. The results of this study reveal that the multi-frequency spatial heating during hybrid nanofluid flow can be utilized as a powerful means to improve the thermal performance of a system operating under different ranges of parameters, even with the presence of porous media and magnetic fields. In addition to different heating frequencies, the variations in amplitude (I) and superposed uniform temperature ( θ os ) to half-sinusoidal heating are also examined thoughtfully in the analysis for different concentrations of Cu–Al2O3 nanoparticles. Compared to the base liquid, the hybrid nanofluid can contribute toward higher heat transfer. [ABSTRACT FROM AUTHOR]

The steady flow of a nanofluid (mixture of titanium dioxide and water) in a rectangular channel under the influence of an inclined magnetic field is studied. The channel contains an upstream hot splitter plate in alignment with the upper and lower plates of the channel. It may be said that two incoming channel flows merge to form a single channel flow. This setup may apply to the heating chamber in which titanium dioxide can be used to enhance the thermal transfer rate. It is observed that the position of the splitter plate (that may act as an electric heater) affects the velocity and temperature of the fluid. Therefore, in order to ensure these facts, the examination of the flow behavior and the temperature distributions in the channel if the splitter is placed at different positions in the upstream have been probed. In addition, the effect of nanoparticles on the convection process has been probed. The streamlines are almost similar for a clear fluid as well as for a nanofluid (for low values of solid volume fraction of nanoparticles (i.e. φ < 0.05 )) for all values of the Reynolds number. However, the rise in the temperature is noted for the nanofluid if the concentration of nanoparticles is increased. The increase in the Reynolds number also supports the enhancement of the Nusselt number and, hence, the thermal transfer rate of the nanofluid. The Nusselt number is dominant in the vicinity of the trailing edge of the splitter because the trailing edge exhibits as a stagnation point. In addition, the maximum Nusselt number for nanofluid at moderate Reynolds number (e.g., Re = 100) is enhanced to 0.3% with respect to the clear fluid. Moreover, obtained results for this particular case are compared with the existing literature, and the results compare well. [ABSTRACT FROM AUTHOR]

The purpose of the current study is to numerically investigate the effects of shape factors of nanoparticles on natural convection in a fluid-saturated porous annulus developed between the elliptical cylinder and square enclosure. A numerical method called the control volume-based finite element method is implemented for solving the governing equations. The modified flow and thermal structures and corresponding heat transfer features are investigated. Numerical outcomes reveal very good grid independency and excellent agreement with the existing studies. The obtained results convey that at a certain aspect ratio, an increment in Rayleigh and Darcy numbers significantly augments the heat transfer and average Nusselt number. Further, enhancement of Rayleigh number increases the velocity of nanofluid, while that of aspect ratio of the elliptical cylinder shows the opposite trend. [ABSTRACT FROM AUTHOR]

The aim of the current study is natural convection analysis conjugated with entropy generation analysis in an incinerator shaped permeable enclosure loaded with Al2O3–H2O nanofluid subjected to the magnetic field with a rectangular wavy heater block positioned on the bottom of the cavity wall. The bottom and top horizontal walls are adiabatic; the inclined and vertical walls are thought to be cooled. Firstly, the governing expressions and standard k–ε turbulence model are rewritten from dimensional form to non-dimensional form using dimensionless parameters such as vorticity and stream function. In the next step, the equation of entropy generation is written in dimensionless form. Then, the system of non-dimensional governing equations is solved by the finite volume method (FVM) conjugated with a non-dimensionalization scheme using ANSYS Fluent. Fine grids (wall y+ < 2) with inflated layers have been used for the higher Rayleigh number. The effects of the Rayleigh number in the laminar region (Ra = 103, 104, and 105) and turbulent region (Ra = 108, 0.5 × 109, and 109), Darcy number (Da = 0.01 and 100), Hartmann number (Ha = 0 and 40), and the nanoparticles ( ϕ = 2 % ) on the entropy generation number and natural convection are investigated. The validation results were in good agreement with those of the literature. The results demonstrate that for the laminar region, the Nusselt number and entropy generation number increase as the Rayleigh number and the Darcy number grow, whereas both of them abate as Hartmann number increases. In the turbulent region, the average Nusselt number decreases by ascending the Darcy number. Also, for turbulent region (Ra = 109), convection flow strength decreases 6.28% when Hartmann number increases from 0 to 40, whereas the entropy generation number increases 31.5% at Da = 0.01. [ABSTRACT FROM AUTHOR]