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In the fluid transport processes extent of irreversibility causes entropy generation that leads to degrading the life span of any engineering system. The main objective of this investigation is to enhance the span of the system by analyzing the effects of various physical parameters. A nanofluid flow over an inclined stretching cylinder is studied to measure entropy generation due to thermal conductivity, Soret and Dufour effects along with viscous dissipation and internal heat source. Buongiorno model is considered as a base structure. The mathematical equations so formed are solved by shooting technique with Gill's fourth order method. Numerical results are validated with Homotopy analysis method through Bvph2.0. Effects of various parameters have been investigated on transport processes like axial velocity, temperature profile, and nanofluid concentration profiles. It seems that higher intensity of the applied magnetic field (M = 0, 1, 2), variable thermal conductivity (ε = 0.1, 0.3, 0.5), and Brinkman number (Br = 0.35) generates more entropy that degrades the system's life. Magnetic parameter and group parameter (1 ≤ Br/Ω1 ≤ 3), changing thermal conductivity all leads to a rise in entropy. In the study, group parameter reducing Bejan number that makes system more sustainable that full fills the aim of the study. Such physical situations generate more entropy must be reduced or avoided to make the system more efficient and long-lasting. [ABSTRACT FROM AUTHOR]

The suspension nanoparticles in non-Newtonian materials convey different applications in the thermal systems, engineering processes, industrial energy developments, extrusion systems, solar system, etc. It is commonly observed that the thermal properties in the various base materials fluctuated and cannot be assumed to be constants. A decomposition of nanofluids is fluctuated and cannot considered as a constant. The objective of this communication is to inspect the thermal mechanism of non-Newtonian nanofluids due to accelerated frame in view of variable thermal conductivity. The modified mathematical relations for Fourier and Fick theories are utilized to model the problem. The nanofluids contain the microorganisms to ensure the thermal stability. The problem is modeled in nonlinear partial differential system which is further communicated via HAM. The convergent analysis is ensured and later on physical illustrations to problem in view of parameters are discussed. It is observed that thermal phenomenon controls due to mixed convection parameter while increasing impact for Williamson fluid parameter is observed. The magnitude of oscillation of Nusselt number due to Prandtl number is enhanced without any phase difference. The obtained results may convey different engineering applications like extrusion systems, chemical processes, thermal management systems, heating and cooling application, plasma, manufacturing processes. [ABSTRACT FROM AUTHOR]

Presently, due to its extraordinary mechanical, thermal, electrical and biomedical facets nanofluids deliver several prospects to exaggerate the propensity of isothermal systems by augmenting the conductivity features of the host fluids. In various areas of the energy partition, nanoparticles show a remarkable measure in energy storage, energy variation, and energy convertible, i.e. thermoelectric plans, petroleum cells, supercapacitors, stellar cells, rechargeable batteries, light-radiating diode and carbon-based light-radiating diode, smart coatings. In this current conversation, we anticipated an unsteady 3D flow of the Sutterby nanofluid consequence of a bidirectional extended surface. To envision the thermophoresis and Brownian motion properties in Sutterby's nanofluid, the Buongiorno association is utilized in an additional refined technique. Variable thermal conductivity with heat source/sink property occurred deliberated considering heat transmission techniques. The appropriate transformation is applied for transposing the PDEs into nonlinear ODEs. For numerical results, the bvp4c programmed is prerequisite for elucidating the subsequent Ordinary differential equations. The distinct performance of the Sutterby nanofluid temperature and the concentration field are designated and discussed in the physical parameter's aspect. It is clear that the temperature of the Sutterby fluid decreases with respect to the ratio of stretching rates parameter and similar developments are observed for the thermophoresis and Brownian motion parameters. Furthermore, the concentration profile declines for sophisticated estimates of the Lewis number and thermophoresis parameters. [ABSTRACT FROM AUTHOR]

Magnetized non-Newtonian models nowadays have attracted many researchers because it is an exciting field in the collaboration of material science, fluid dynamics, and applied physics. Their unique properties and adaptability render them invaluable across various technological and industrial applications, promising further innovations as research advances. This research unveils the intricate rheological and thermal behavior of magnetized non-Newtonian nanofluids undergoing peristaltic motion. The study aims to enhance engineering design techniques for optimal biophysiological performance by incorporating second-order slip, convective conditions, and temperature-dependent thermal conductivity. The Buongiorno nanofluid model is adopted to investigate heat and mass transfer phenomena, while the Prandtl non-Newtonian fluid model is employed to comprehend the complex rheological characteristics of the fluid. A long-wavelength approximation with a low Reynolds number was employed to simplify the governing equations. Analytical solutions have been obtained by solving the nonlinear transformed equations using the Homotopy perturbation technique. The findings are validated with previous literature and indicate that magnetic fields play a key role in controlling peristaltic flow behavior and nanofluid pumping rates. Moreover, the interplay between non-Newtonian rheology and nanofluid parameters significantly affects temperature distribution patterns. An increase in the species Biot number and thermophoresis parameter leads to improved concentration behavior. Conversely, a reversible trend is noted with the augmentation of the Prandtl number, Eckart number, variable thermal conductivity, and Brownian motion parameters. This research provides new insights into magnetohydrodynamic transport mechanisms in peristaltic systems. The modeling approach, coupled with analysis, lays the background for improved fluid circulation, oxygen delivery, waste removal, and nutrient transport in biomedical applications. Specifically, the findings are important for advancing the design of peristaltic pumps tailored for targeted drug delivery and optimizing fluid flow within gastrointestinal tracts.

Abstract Owing to valuable significance of bioconvective transport phenomenon in interaction of nanoparticles, different applications are suggested in field of bio-technology, bio-fuels, fertilizers and soil sciences. It is well emphasized fact that thermal outcomes of nanofluids can be boosted under the consideration of various thermal sources. The aim of current research is to test the induction of induced magnetic force in bioconvective transport of non-Newtonian nanofluid. The rheological impact of non-Newtonian materials is observed by using Casson fluid with suspension of microorganisms. The chemical reaction effected are interpreted. The thermal conductivity of material is assumed to be fluctuated with temperature fluctuation. The flow pattern is endorsed by stretching surface following the stagnation point flow. Under the defined flow assumptions, the problem is formulated. A computational software with shooting technique is used to present the simulations. A comprehensive analysis for problem is presented. It is claimed that the interpretation of induced magnetic force exclusively enhanced the thermal phenomenon.

Owing to valuable significance of bioconvective transport phenomenon in interaction of nanoparticles, different applications are suggested in field of bio-technology, bio-fuels, fertilizers and soil sciences. It is well emphasized fact that thermal outcomes of nanofluids can be boosted under the consideration of various thermal sources. The aim of current research is to test the induction of induced magnetic force in bioconvective transport of non-Newtonian nanofluid. The rheological impact of non-Newtonian materials is observed by using Casson fluid with suspension of microorganisms. The chemical reaction effected are interpreted. The thermal conductivity of material is assumed to be fluctuated with temperature fluctuation. The flow pattern is endorsed by stretching surface following the stagnation point flow. Under the defined flow assumptions, the problem is formulated. A computational software with shooting technique is used to present the simulations. A comprehensive analysis for problem is presented. It is claimed that the interpretation of induced magnetic force exclusively enhanced the thermal phenomenon. [ABSTRACT FROM AUTHOR]

This article describes the significance of ‘Stefan suction/blowing’ on the forced flow of nanoliquid past the surface of a ‘plate’ with temperature-obeying ‘thermal conductivity’ and ‘fluid viscosity’ with ‘zero nanoparticle flux’ at the ‘plate’ that has not till been attended by anyone and thus it points to the originality of present investigation and here lies the novelty of our work. Nanofluid flow is modeled with the help of ‘Buongiorno's two-phase model’ which contains the instantaneous virtue of thermophoresis diffusion and Brownian movement. This investigation shows that the speed of heat transport is remarkably augmented by the variable ‘thermal conductivity’ and variable ‘viscosity parameters’ which is the main contribution of this research. Due to changeable viscosity, reducing nature of velocity as well as the reducing nature of concentration of the nanoparticles near the ‘plate’ are observed. Due to Stefan's blowing parameter, fluid velocity augments but ‘temperature’ is observed to reduce for mounting values of Stefan's blowing parameter. 3.2 % reduction in skin-friction coefficient is noted when variable viscosity parameter reduces from -6 to -8. Moreover, 7.1 % reduction in heat transfer as well as mass transfer is noted when the variable thermal conductivity parameter rises from 0.2 to 0.4. The consequence of this inspection exposes a variation of exciting diversity which claims extra exploration of the present study.

The current study focuses on nonlinear convective nanofluid (MoS2 − vacuum pump oil) flow with different shapes in an annular region across coaxial cylinders in a permeable media. At the interface of coaxial cylinders velocity slip and temperature jump conditions are incorporated. The phenomenon of thermal transport is enhanced by amalgamating generalized Fourier law with variable thermal conductivity. The Hamilton-Crosser nanofluid flow model is adopted here. The nonlinear equations that govern the flow are simplified via a similarity transformation. For the numerical solution, the bvp4c algorithm is utilized. Graphical analysis is employed to illustrate how important factors affect the temperature and velocity fields. Computational values of the drag force coefficient and Nusselt number are summarized in tabular form. The study reveals that the velocity field upsurges on enhancing the nonlinear convective and radii ratio parameters. On amplifying the rarefaction and thermal conductivity parameters, the thermal field upsurges. Skin friction coefficient exhibits a decreasing behavior on incrementing the porosity parameter. Heat flux diminishes more rapidly by boosting the concentration of nanoparticles. A considerable correlation is apparent graphically and in tabular form by comparing the results of the current investigation with published studies. [ABSTRACT FROM AUTHOR]

The study on heat and mass transportation play a noteworthy role in the liquid atmosphere wherever nearby is considerable temperature and deposition of diffusion transport in a stirring wedge. Heat and mass transport on fluids discoveries prominence in development of manufacturing and industrial processes such as petroleum reservoirs, nuclear waste disposal, heat exchanger devices, etc. By taking this into, the present study exhibited here to consider the impact of variable fluid properties on nanofluid flow over a wedge. The analysis of the flow has been analyzed consisting with the influences of heat generation/absorption and chemical reaction. It is accepted to have fluid viscosity and thermal conductivity as an opposite capability and conventional capacity of temperature, separately. The succeeding nonlinear ordinary differential circumstances are measured numerically utilizing the fourth order of the Runge-Kutta technique jointly with the shooting method. The consequence of the suitable parameters concerning the flow has been explained through graphs and tables, together with the necessary contentions/conversation. The accompanying investigation exhibits that the fluid temperature is higher within the view of a variable viscosity and heat generation parameters. It is additionally seen that the wall stress diminishes with expanding velocity slip.

The present investigation deals with the steady three-dimensional flow and heat transfer of nanofluids due to stretching sheet in the presence of magnetic field and heat source. Three types of water based nanoparticles namely, copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are considered in this study. The temperature dependent variable thermal conductivity and thermal radiation has been introduced in the energy equation. Using suitable similarity transformations the dimensional non-linear expressions are converted into dimensionless system and are then solved numerically by Runge-Kutta-Fehlberg scheme along with well-known shooting technique. The impact of various flow parameters on axial and transverse velocities, temperature, surface frictional coefficients and rate of heat transfer coefficients are visualized both in qualitative and quantitative manners in the vicinity of stretching sheet. The results reviled that the temperature and velocity of the fluid rise with increasing values of variable thermal conductivity parameter. Also, the temperature and normal velocity of the fluid in case of Cu-water nanoparticles is more than that of Al2O3- water nanofluid. On the other hand, the axial velocity of the fluid in case of Al2O3- water nanofluid is more than that of TiO2nanoparticles. In addition, the current outcomes are matched with the previously published consequences and initiate to be a good contract as a limiting sense.

This paper analyzes the influence of mixed convective fourth grade nanofluid flow by a stretchable Riga device in the presence variable thermal conductivity and mass diffusivity. Heat and mass transportation are considered with Cattaneo–Christov (CC) model. Thermal radiation and dissipation are also taken in the energy expression. Suitable transformation is employed to reduce partial differential system into nonlinear ordinary system. The governing nonlinear expression is solved via optimal homotopy analysis method. Impact of different physical variables is discussed via graphs. Velocity profile is enhanced for higher values of cross viscous parameter and fourth grade fluid variable. Fluid temperature enhances for higher estimation of thermal relaxation parameter but reverse behavior is seen for solutal concentration variable on nanoparticle concentration. [ABSTRACT FROM AUTHOR]

In the present study, a magnetized micropolar nanofluid and motile micro-organism with variable thermal conductivity over a moving surface have been discussed. The mathematical modeling has been formulated using a second-grade fluid model and a revised form of the micropolar fluid model. The governing fluid contains micro-organisms and nanoparticles. The resulting nonlinear mathematical differential equations have been solved with the help of the homotopy analysis method. The graphical and physical features of buoyancy force, micro-organisms, magnetic field, microrotation, and variable thermal conductivity have been discussed in detail. The numerical results for Nusselt number, motile density number, and Sherwood number are presented with the help of tables. According to the graphical effects, it is noted that the buoyancy ratio and the bioconvection parameter resist the fluid motion. An enhancement in the temperature profile is observed due to the increment in thermal conductivity. Peclet number tends to diminish the motile density profile; however, the viscoelastic parameter magnifies the motile density profile. [ABSTRACT FROM AUTHOR]

In thoughtfulness of researchers and technologists in the arena of nanoscience and nanotechnology owing to reduced thermal properties of the usual base fluids, a new-fangled sort of fluids acknowledged as nanofluids have been established, which contains nanoparticles deferred in a hostfluid. For instance, nanofluids have superior heat transport enactment, because deferred nanoparticles have better thermal conductivity allied with base liquid. Here elaborated 3D flow of a Carreau nanoliquid is influenced by a bidirectional stretched surface. To visualize the properties of Brownian motion and thermophoresis on the Carreau nanoliquid, the Buongiorno's relation is exploited in a more proficient tactic. Variable thermal conductivity with the possessions of heat source/sink is pondered for heat transfer mechanisms. Suitable conversion is used to change the PDEs into non-linear ODEs. Numerically, bvp4c scheme is prompted to crack the resulting ODEs. The discrete behaviors for shear thinning/thickening of nanoliquid temperature and concentration field are described and deliberated in aspect for somatic parameters. It is exposed that the Carreau liquid temperature declines for Prandtl number and conflicting trends are being noted for Brownian and thermophoresis parameters. Moreover, heat transfer amount diminishes for higher Brownian and thermophoresis parameters. An assessment between two different approaches namely, bvp4c and homotopy analysis method, is also presented in tabular form which ensure that our outcomes are more precise. [ABSTRACT FROM AUTHOR]

The present work inspects the entropy generation on radiative heat transfer in the flow of variable thermal conductivity optically thin viscous Cu–water nanofluid with an external magnetic field through a parallel isothermal plate channel. Our approach uses the power series from the governing non-linear differential equations for small values of thermal conductivity variation parameter which are then analysed by various generalizations of Hermite- Padé approximation method. The influences of the pertinent flow parameters on velocity, temperature, thermal conductivity criticality conditions and entropy generation are discussed quantitatively both numerically and graphically. A stability analysis has been performed for the rate of heat transfer which signifies that the lower solution branch is stable and physically acceptable, whereas the upper solution branch is unstable.

White crystalline powder (aluminum oxide-Al2O3) and water are the products often formed after the heating of aluminum hydroxide. In this report, boundary layer flow of two different nanofluids (i.e., 36 nm Al2O3-water and 47 nm Al2O3-water) over an upper horizontal surface of a paraboloid of revolution under the influence of magnetic field is presented. The combined influence of magnetic field strength, electric current density, electric charge, electron collision time, and the mass of an electron in the flows are considered in the governing equations. Three-dimensional transport phenomenon was considered due to the influence of the Lorentz force (F→) along the z-direction as in the case of Hall currents. In this study, the dynamic viscosity and density of the nanofluids are assumed to vary with the volume fraction ϕ. The dimensional governing equations were non-dimensionalization and parametrization using similarity variables. The corresponding boundary value problem was transformed into initial value problem using the method of superposition and solved numerically using fourth-order Runge-Kutta method with shooting technique (RK4SM). Magnetic field parameter is seen to have dual effects on the cross-flow velocity profiles of both nanofluids. The maximum cross-flow velocity is attained within the fluid domain when 36 nm nanoparticles alumina is used. The cross-flow velocity gradient at the wall increases with magnetic field parameter (M) and also increases significantly with Hall parameter at larger values of M. [ABSTRACT FROM AUTHOR]

The present article explores the influence of variable fluid properties on nanofluid flow over a wedge. The flow analysis has been considered under the effect of surface slip. It is supposed to have fluid viscosity and thermal conductivity as an inverse function and linear function of temperature, respectively. The resulting nonlinear ordinary differential equations are solved numerically using RK-4 method together with shooting procedure. The consequence of involved pertinent parameters on the flow province has been discussed through graphs and tables coupled with required discussion. Our analysis conveys that the fluid temperature is higher in the presence of variable viscosity parameter and thermal conductivity parameter. It is also observed that the wall stress decreases with increasing velocity slip parameter. [ABSTRACT FROM AUTHOR]

The temperament of stream characteristic, heat and mass transfer of MHD forced convective flow over a linearly expanding porous medium has been scrutinized in the progress exploration. The germane possessions of the liquid like viscosity along with thermal conductivity are believed to be variable in nature, directly influenced by the temperature of flow. As soon as gaining the system of leading equations of the stream, Lie symmetric group transformations have been employed to come across the fitting parallel conversions to alter the central PDEs into a suit of ODEs. The renovated system of ODE with appropriate boundary conditions is numerically solved with the assistance of illustrative software MAPLE 17. The consequences of the relevant factors of the system have been exemplified through charts and graphs. An analogous qualified survey has been prepared among present inquiry and subsisting reads and achieved an admirable accord between them. The variable viscosity parameter has more significant effect on nanofluid velocity than regular fluid and temporal profile as well as nanoparticle concentration is also influenced with variable viscosity. [ABSTRACT FROM AUTHOR]

The primary objective of the present work is to study the effects of heat transfer and entropy production in a nanofluid flow over a curved surface. The influences of Lorentz force and magnetic heating caused by the applied uniform magnetic field and energy dissipation by virtue of frictional heating are considered in the problem formulation. The effects of variable thermal conductivity are also encountered in the present model. The dimensional governing equations are reduced to dimensionless form by introducing the similarity transformations. The dimensionless equations are solved numerically by using the Chebyshev⁻Gauss⁻Lobatto spectral method (CGLSM). The rate of increase/increase in the local Nusselt number and skin friction coefficient are estimated by using a linear regression model. The expression for dimensionless entropy production is computed by employing the solutions obtained from dimensionless momentum and energy equations. Various graphs are plotted in order to examine the effects of physical flow parameters on velocity, temperature, and entropy production. The increase in skin friction coefficient with magnetic parameter is high for nanofluid containing copper nanoparticles as compared to silver nanoparticles. The analysis reveals that velocity, temperature, and entropy generation decrease with the rising value of dimensionless radius of curvature. Comparative analysis also reveals that the entropy generation during the flow of nanofluid containing copper nanoparticles is greater than that of containing silver nanoparticles.

In this article, two-dimensional laminar-forced convection nanofluids flow over a stretching surface in a porous medium has been studied. The governing partial differential equations with the corresponding boundary conditions are reduced to a set of ordinary differential equations with the appropriate boundary conditions using similarity transformation, which is then solved numerically by the fourth order Runge–Kutta integration scheme featuring a shooting technique. Different models of nanofluid based on different formulas for thermal conductivity and dynamic viscosity are used. Different types of nanoparticles as copper, silver, alumina and titanium Oxide with water and Ethylene glycol as their base fluids has been considered. The influence of significant parameters such as nanoparticle volume fraction, kind of nanofluid, Magnetic parameter and Reynolds number on the flow and heat transfer characteristics is discussed. The influence of significant parameters such as Thermal conductivity parameter, volume fraction of the nanoparticles, Permeability parameter, suction/injection parameter and Velocity ratio parameter on the flow and heat transfer characteristics is discussed. It was found that choosing Titanium oxide as the nanoparticle and Ethylene glycol as base fluid proved to have the highest cooling performance for this problem.

The current paper applied dissipative particle dynamics (DPD) approach to investigate heat transfer within nanofluids. The DPD approach was applied to study natural convection in a differential heated enclosure by considering the viscosity and the thermal conductivity of the nanofluid to be dual function of temperature and volume fraction of nanoparticles. Experimental data for viscosity and thermal conductivity are incorporated in the current DPD model to mimic energy transport within nanofluids. This incorporation is done through the modification of the dissipative weighting function that appears in the dissipative force vector and the dissipative heat flux. For the entire range of Rayleigh number considered in this study, it was found that the DPD results show a deterioration in heat transfer in the enclosure due to the presence of nanoparticles for φ > 4%. However, some slight enhancement is shown to take place for small volume fraction of nanoparticles, φ ≤ 4%. The DPD results experienced some degree of compressibility at high values of Rayleigh number Ra ≥ 10 5 . [ABSTRACT FROM AUTHOR]

The motion of nanofluid (water and 36 nm alumina nanoparticles) along upper horizontal surface of a paraboloid of revolution in the presence of nonlinear thermal radiation, Lorentz force and space dependent internal heat source within thin boundary layer is investigated theoretically. It is assumed that buoyancy induces the flow over this kind of surface which is neither a horizontal/vertical nor cone/wedge, hence suitable buoyancy model for this case of fluid flow is presented. The viscosity and thermal conductivity are assumed to vary with volume fraction and suitable models for the case 0 % ≤ ϕ ≤ 0.8% are adopted. The transformed governing equations are solved numerically using Runge-Kutta fourth order along with shooting technique (RK4SM). Good agreement is obtained between the solutions of RK4SM and MATLAB bvp5c for limiting case. The influence of pertinent parameters are illustrated graphically and discussed. It is found that temperature and velocity functions are maximum at higher values of internal space dependent heat source. Local heat transfer rate is maximum at smaller values of internal space dependent heat source. [ABSTRACT FROM AUTHOR]

The present work inspects the entropy generation on radiative heat transfer in the flow of variable thermal conductivity optically thin viscous Cu-water nanofluid with an external magnetic field through a parallel isothermal plate channel. Our approach uses the power series from the governing non-linear differential equations for small values of thermal conductivity variation parameter which are then analysed by various generalizations of Hermite- Padé approximation method. The influences of the pertinent flow parameters on velocity, temperature, thermal conductivity criticality conditions and entropy generation are discussed quantitatively both numerically and graphically. A stability analysis has been performed for the rate of heat transfer which signifies that the lower solution branch is stable and physically acceptable, whereas the upper solution branch is unstable. [ABSTRACT FROM AUTHOR]

In this paper, the unsteady magnetohydrodynamic (MHD) boundary layer slip flow and heat transfer of nanofluid in a solar collector, modeled mathematically as a nonlinear stretching sheet is investigated numerically. The variable thermal conductivity is assumed as a function of temperature and the wall-slip conditions are utilized at the boundary. The similarity transformation technique is used to reduce the governing boundary value problem to a system of nonlinear ordinary differential equations (ODEs) and then solved numerically. The numerical values obtained for the velocity and temperature depend on nanofluid volume concentration parameter, unsteadiness parameter, suction/injection parameter, thermal conductivity parameter, slip parameters, MHD parameter and thermal radiation parameter. The effects of various parameters on the flow and heat transfer characteristics are presented and discussed through graphs and tables. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate stagnation-point flow of nanofluids over an isothermal stretching sheet. The volume fraction of nanoparticles at the sheet is assumed to be passively controlled. Furthermore, due to low volume fraction of nanoparticles and dilute nanofluid, the thermal conductivity and dynamic viscosity of the nanofluid are assumed to be linear functions of the volume fraction of nanoparticles. In order to study the effects of a plethora of parameters on the boundary layer flow and heat and mass transfer, a practical range of these parameters have been utilized. An accurate numerical solution of the governing equations based on the finite difference method is obtained and the effect of various physical parameters such as the Prandtl number, Lewis number, thermophoresis parameter, and the Brownian motion parameter on the thermal, hydrodynamic, and concentration boundary layers is evaluated. In order to examine the alteration of the thermal convective coefficient, a dimensionless heat transfer enhancement ratio parameter is introduced. The results show that the variation of different thermodynamic parameters induces substantial impression on the behavior of the nanoparticles distribution. For example, it is found that an increase in the value of the Lewis number leads to a decrease in the value of the non-dimensional nanoparticles volume fraction at the sheet, but it does not have any influence on the thermal and hydrodynamic boundary layers. Increasing the Prandtl number is predicted to decrease the thermal boundary layer thickness and the volume fraction of nanoparticles at the surface. In most instances, the heat transfer augments in the presence of nanoparticles. [ABSTRACT FROM AUTHOR]

This paper presents a time dependent boundary layer flow and heat transfer of an incompressible Oldroyd-B nanofluid past an impulsively stretching sheet. Heat transfer analysis is carried out by taking thermal conductivity as a function of temperature. The non-dimensionalized partial differential equations are solved using bivariate spectral quasi-linearization method). The employs the concept of quasi-linearization to obtain a linear system of partial differential equations which is subsequently solved using a spectral collocation method that uses bivariate Lagrange interpolating polynomials as basic functions. This method is found to converge rapidly and is very effective in yielding accurate results. Numerical results have been presented graphically to illustrate the details of flow and heat transfer characteristics and their dependence on some of the physical parameters. [ABSTRACT FROM AUTHOR]

The effects of nanoparticles diameter and concentration on natural convection heat transfer of a nanofluid around a vertical cone embedded in a Darcy porous medium is theoretically investigated utilizing the drift-flux model. The thermal conductivity and the viscosity of the nanofluid are assumed as simultaneous functions of temperature and local volume fraction of nanoparticles using experimental correlations. In addition, the flux of nanoparticles on the surface of the cone is assumed to be zero. An efficient mathematical approach with a self-similar solution is utilized to theoretically analyze the boundary layer heat and mass transfer of an Al 2 O 3 –water nanofluid. The reduced system of ordinary differential equations are general and can be solved for any arbitrary functions of thermal conductivity and viscosity. The analysis of the nanofluid natural convection flow is accomplished for two cases of (i) T w > T ∞ and (ii) T w < T ∞ . The results show that using nanoparticles would not (would) enhance the heat transfer from the cone for the case of a cone with a hot surface (cold surface). A decrease in the size of nanoparticles or an increase in the volume fraction of nanoparticles causes a decline in the heat transfer rate from the cone when the cone surface is hot. Finally, a comparison between the non-homogenous model (drift-flux model) and the homogenous model of nanofluids is performed. The results demonstrate that the drift-flux model tends to the homogeneous model as the size and volume fraction of nanoparticles increase. [ABSTRACT FROM AUTHOR]

In this article, two-dimensional laminar-forced convection nanofluids flow over a stretching surface in a porous medium has been studied. The governing partial differential equations with the corresponding boundary conditions are reduced to a set of ordinary differential equations with the appropriate boundary conditions using similarity transformation, which is then solved numerically by the fourth order Runge-Kutta integration scheme featuring a shooting technique. Different models of nanofluid based on different formulas for thermal conductivity and dynamic viscosity are used. Different types of nanoparticles as copper, silver, alumina and titanium Oxide with water and Ethylene glycol as their base fluids has been considered. The influence of significant parameters such as nanoparticle volume fraction, kind of nanofluid, Magnetic parameter and Reynolds number on the flow and heat transfer characteristics is discussed. The influence of significant parameters such as Thermal conductivity parameter, volume fraction of the nanoparticles, Permeability parameter, suction/injection parameter and Velocity ratio parameter on the flow and heat transfer characteristics is discussed. It was found that choosing Titanium oxide as the nanoparticle and Ethylene glycol as base fluid proved to have the highest cooling performance for this problem. [ABSTRACT FROM AUTHOR]

Low thermal conductivity is the major issue in heat transfer problems. It can be increased through the saturation of nanoparticles into base liquid. They have wide applications in engineering, electronics as well as in biomedicines. For cancer treatment magnetic nanoparticles are very effective. Nanofluids are excessively used as coolants in industries for example in automobiles, radiators, heat exchangers, cooling of microchips, nanocryosurgery and in cryopreservation etc. This attempt addresses the flow behavior of MHD fluid considering of nanoparticles. Here, the stretchable surface is responsible for fluid flow. Energy equation is formulated under the impacts of Joule heating and viscous dissipation. Varying thermal conductivity alongside with varying mass diffusivity are also incorporated. Flow analysis is exhibited by Thermophoresis and Brownian diffusion. Movement of heat and mass are addressed by using improved diffusive theory. It is noted that Brownian and thermophoresis diffusions will appear under the theory of modified fluxes. Behavior of unlike parameters in nanofluid velocity, fluid temperature and particles concentration are disclosed graphically. Skin friction co-efficient (drag force) is plotted. Both temperature and concentration profiles raises with enlarged thermal conductivity parameter and mass diffusivity parameter. Also local inertia coefficient parameter and Darcy porosity parameter diminishes the drag force. [ABSTRACT FROM AUTHOR]