Natural Convection Flow Of Nanofluid Research Articles

A machine learning approach for entropy due to natural convection flow of a nanofluid under the uniform inclined magnetic field

In this study, entropy generation of natural convection flow of Cu-water nanofluid under the influence of a uniform inclined magnetic field (MF) is firstly modeled by a machine learning approach using the data obtained from a numerical process. The two dimensional, time dependent dimensionless equations are numerically solved by using global radial basis function (RBF) method in spatial derivatives and the second order backward differentiation formula (BDF2) in time derivatives. In a set of combined dimensionless problem parameters, numerical simulations are performed. In the obtained data, the inputs are a set of combined dimnesionless problem parameters and the outputs are entropy indicators. Then, global and local entropy indicators are modeled by Neural Network (NN). In view of smaller mean squared error metric results, small number of layers or layer sizes in NN seems enough in smaller data while trilayer NN (TNN) is a better modeler in case of larger data.

Nonlinear natural convective nanofluid flow past a vertical plate

Nonlinear natural convective nanofluid flow past a vertical plate

Thermal performance investigation of transient natural convective nanofluid flow in a square cavity with inclined periodic magnetic field

The goal of this paper is to analyze the thermal exhibition of transient free convective nanofluid flow in a square cavity with inclined periodic magnetic field using one-component thermally equilibrium homogeneous model. Distinct thermal settings (constant, parabolic, and sinusoidal) for the left heated wall are deliberated when the right wall of the cavity is cold and the horizontal walls are insulated. For numerical simulations, eight types of nanofluids consisting Cu, Co, Zn, and Al2O3 nanoparticles along with H2O and kerosene as base fluids have been employed. During numerical computation, the impacts of different factors (Hartmann number, Rayleigh number, nanoparticles volume fraction, period, and inclination angle) on the fluid flow and heat transfer are examined. The numerical results show that cobalt-kerosene nanofluid distributes the maximum heat transfer rate compared to other 7 types of nanofluids. The results also indicate that sinusoidal thermal scenery at the left heated wall delivers the uppermost average Nusselt number compared to the other types of thermal approaches. The optimum thermal performance is achieved at magnetic field's inclination angle δ=π3 and period number λ = 1 for the case of sinusoidal scenery.

A Radiative Chemical Process for the Methylene Blue Degradation by Natural Convective Nanofluid Flow over an Upright Cone.

An upstraight cone with nonisothermal surface velocity, temperature, and concentration was investigated using a numerical solution approach to simulate MHD, MB dye, and various nanofluid flows. Numerical evaluation of the flow field equation was carried out using an excellent finite difference method after it has been converted into a dimensionless form. Different heat transfer occurrences were observed depending on temperature, velocity, and concentration when using several types of nanofluids (TiO, Ag, Cu, and Al2O3Z3). The amount of MB dye that was degraded by the synthesized nanofluids under the influence of sunlight irradiation was 81.40 percent as a catalyst (carbon nanodots). The parametric analysis of various features of flow fields has been shown using graphs. It was observed that heat is generated from the cone during the sun light irradiation reaction, heat is transferred to MB dye containing nanofluids, and heat interacts with nanofluids and is involved in the chemical reaction with the assistance of electrons. As MB dye degrades in the absence of catalysts (carbon nanodots), it is only 52 percent effective. MB dye is degraded at 81.40 percent, then becomes stable, and takes 120 minutes to degrade in nanofluids containing MB dye with catalysts (carbon nanodots).

Darcy–Forchheimer natural convection flow of SWCNTs-EG-based nanofluid along a complex roughened surface

The study of heat transfer in natural convection flow of nanofluid (mixture of SWCNTs and ethylene glycol fluid) through a complex roughened surface saturated in a porous medium is investigated. The governing equations in terms of nonlinear PDEs are derived using Darcy–Forchheimer and Tiwari and Das models and made dimensionless using transformation. A finite difference scheme with backward and central differences approximations is used to conduct numerical solution. Recently, researchers have focused on the use of roughened surfaces or suspension of nanoparticles in base fluid to improve heat transfer rate. The objective of this study is to quantify the increase in heat transfer rate due to complex roughened surface and nanofluid. The results reveal that total heat transfer rate raises higher in nanofluid as compared to largest amplitude of harmonic wave. The absolute value of drag coefficient and rate of total heat transfer grow by increasing the value of Darcy number. Near the leading edge, the total heat transfer rate declines up-to certain node value which is 0.2125 and 0.2071 in the absence and presence of nanofluid and increases away from these node values. Streams slices and isotherm lines expand in case of largest amplitude of harmonic wave and nanofluid.

Thermal influence of heated fin on MHD natural convection flow of nanofluids inside a wavy square cavity

Thermal influence of heated fin on MHD natural convection flow of nanofluids inside a wavy square cavity

Double diffusion and Hall effects on MHD sinusoidal natural convection flow of silver water-based nanofluid from a porous vertical plate

This paper scrutinizes Hall current, Soret and Dufour impacts on natural convective flow of nanofluid attributable to variation in sinusoidal surface temperature over a vertical plate through a porous medium with strong transverse magnetic field applied normally to the flow. In this regard, the silver metal is considered as nanoparticles with water as base fluid. The overlapping multi-domain bivariate spectral local linearization method (OMD-BSLLM) has been utilized to solve the dimensionless governing equations which are attained by means of appropriate transformations. The obtained results are portrayed via graphical and tabular formations to inspect flow fields, shear stresses, heat and mass transmission characteristics for varying thermo-physical parameters. We found that there is an enhancement in the flow fields, shear stresses and heat transportation with the use of silver nanoparticles. Thermal and concentration boundary layer thickness enhance by using porous material, whereas diminish with improvement in Hall effect and ratio of buoyancy forces. The flow characteristics decline with the inclusion of porous medium while elevates with increment in Hall parameter. Moreover, an upgrade in thermal-diffusion correspond to a substantial growth in concentration field along with mass transfer rate. Current analysis can be useful in MHD energy generators, and industrial applications such as heating and cooling procedures owing to the involvement of nanoparticles having superior thermal conductivity features.

Natural convective nanofluid flow characteristics with Brownian motion effect in an annular space between confocal elliptic cylinders

The principal aim of this work is to study numerically the natural convection in an annular space between confocal elliptic cylinders. The Brownian motion was added based on the thermal conductivity model and the simulation was carried out using finite volume control method. Various nanofluids with different volume concentrations were undertaken ranging from 2% to 6% and various Rayleigh numbers were tested for different particles. The isotherms and stream function are presented and it was clearly seen that by increasing the Rayleigh number, the heat transfer rate increases on the domain. On the other hand it was noticed that the heat transfer enhancement is less sensitive to the nanoparticles when the Brownian motion was considered

Evaluation of Magnetohydrodynamics of Natural Convective Heat Flow over Circular Cylinder Saturated by Nanofluid with Thermal Radiation and Heat Generation Effects

The current study focuses on the natural-convection flow of nanofluids with boundary layer over a circular cylinder of uniform thermal wall with varying magnetic force from 0 to 1.5, radiative effects from 0 to 1, heat generation effects from 0 to 1, and Joule heating effects from 0 to 1. The problem is represented in the form of partial differential equations. The dimensional form of the equations is converted into a dimensionless form with the help of suitable stream functions. Then, the resultant equations are further reduced into the system of first-ordered differential equations, and the Keller box scheme is applied to obtain a solution numerically with the help of MATLAB code. The numerical solutions for Nusselt number, skin friction coefficient, Sherwood number, velocity profile, temperature profile, and concentration profile are represented with the help of graphs. The most interesting fact of the analysis is the flow of the fluid; the heat-mass and energy transfer rates could be managed in a controlled way through slight variations in the Brownian motion parameter from 0.1 to 0.7, in the Lewis number from 1 to 40, in the Eckert number from 0.1 to 0.4, in the thermophoresis parameter from 0.1 to 0.7, in the Prandtl number from 0.1 to 0.7, and in the buoyancy ratio from 0.1 to 0.7, as it is here analyzed and discussed.

Impact of Non-Uniform Periodic Magnetic Field on Unsteady Natural Convection Flow of Nanofluids in Square Enclosure

In this article, unsteady free convective heat transport of copper-water nanofluid within a square-shaped enclosure with the dominance of non-uniform horizontal periodic magnetic effect is investigated numerically. Various nanofluids are also used to investigate temperature performance. The Brownian movement of nano-sized particles is included in the present model. A sinusoidal function of the y coordinate is considered for the magnetic effect, which works as a non-uniform magnetic field. The left sidewall is warmed at a higher heat, whereas the right sidewall is cooled at a lower heat. The upper and bottom walls are insulated. For solving the governing non-linear partial differential equation, Galerkin weighted residual finite element method is devoted. Comparisons are made with previously published articles, and we found there to be excellent compliance. The influence of various physical parameters, namely, the volume fraction of nanoparticles, period of the non-uniform magnetic field, Rayleigh number, the shape and diameter of nanoparticles, and Hartmann number on the temperature transport and fluid flow are researched. The local and average Nusselt number is also calculated to investigate the impact of different parameters on the flow field. The results show the best performance of heat transport for the Fe3O4-water nanofluid than for other types of nanofluids. The heat transport rate increases 20.14% for Fe3O4-water nanofluid and 8.94% for TiO2-water nanofluid with 1% nanoparticles volume. The heat transportation rate enhances with additional nanoparticles into the base fluid whereas it decreases with the increase of Hartmann number and diameter of particles. A comparison study of uniform and non-uniform magnetic effects is performed, and a higher heat transfer rate is observed for a non-uniform magnetic effect compared to a uniform magnetic effect. Moreover, periods of magnetic effect and a nanoparticle’s Brownian movement significantly impacts the temperature transport and fluid flow. The solution reaches unsteady state to steady state within a very short time.

Finite element analysis on the hydrothermal pattern of radiative natural convective nanofluid flow inside a square enclosure having nonuniform heated walls

AbstractThe present article enlightens us on the hydrothermal pattern of a steady incompressible laminar natural convective nanofluid flow inside a heated square chamber. The square enclosure is filled with water‐based spherical‐shaped ferrous (Fe3O4) nanoparticles. Magnetic effect and thermal radiation are presumed within the flow. The left‐sided vertical wall and one bottom wall of the chamber are nonuniformly and uniformly heated, while the remaining right‐sided vertical wall is isothermally cooled at a constant temperature and the upper wall is insulated. A detailed analysis is conducted to exhibit that how nonuniform and uniform heated walls influence flow within the square chamber. The leading dimensional equations are made into a dimensionless form using apposite similarity variables and the Galerkin finite element technique is executed to solve those equations. The grid independence test and a parallel comparison with existing literature are presented to verify the validity of the outcomes. The streamlines, isotherms, temperature, velocities, and average Nusselt number are depicted through several graphs for several parametric values of Rayleigh number, Hartmann number, thermal radiation, and nanoparticle volume fraction. The outcomes showed that increasing nanoparticle concentration and Rayleigh number lead to improve the Nusselt number, while heat transport is reduced for Hartmann number and radiation parameter. The uniformly heated walls convey better heat transport as compared to nonuniformly heated walls.

Numerical Investigation of Endothermic/Exothermic Reaction in MHD Natural Convective Nano-Fluid Flow over a Vertical Cone with Heat Source/Sink

The significance of natural convective MHD flow of nano-fluid over a vertical cone with Brownian motion, viscous dissipation, heat generation, thermophoresis, and chemical reaction in porous surroundings is discussed in this article. The leading non-linear PDEs are transmuted by using applicable similarity transform and the reformed equations, along with the boundary conditions, are numerically solved by finite difference technique of bvp4c code via MATLAB code. The significance of the controlling parameters on velocity, temperature, and concentration are portrayed vividly. Furthermore, skin friction, Nusselt number, and Sherwood number are charted for diverse parameters. It is worth mentioning that impact of heat source ( ) on velocity and temperature is remarkable. Molar species concentration is accentuated with progressive values of Dufour number, while it is the opposite for velocity and temperature profiles. Moreover, thermal energy is absorbed due to the application of endothermic chemical reaction that cools the surroundings, which minimizes the diffusion rate of molecules and, therefore, less molar concentration is occurred. Conduction is the dominant mechanism for heat transport by applying Rayleigh number. The profiles of skin friction, Nusselt number, and Sherwood number are reduced with higher values of Rayleigh number. The present study has an appreciable impact on many engineering applications, such as magnetic storage media, the cooling systems of electronic devices, nuclear power plants, the chemical industry, and many more.
 HIGHLIGHTS
 
 Heat source/sink is a key parameter for rate of heat/mass transfer of nanofluid flow
 Exothermic chemical reaction plays a dynamic role to boost the nanofluid flow motion
 Higher Rayleigh number decays the flow rate as well as rate of heat and mass transfer
 The study incorporates the application of Brownian motion in nanofluid flow
 Current study has diverse applications in cooling process
 
 GRAPHICAL ABSTRACT

Natural Convective Effects on MHD Boundary Layer Nanofluid Flow over an Exponentially Accelerating Vertical Plate

The problem of unsteady natural convective nanofluid flow along with an exponentially accelerating vertical plate under the influence of transverse magnetic field is discussed in two important cases when the magnetic lines of force are fixed relative to the fluid or the moving plate. The governing equations are transformed into dimensionless form and tackled with the usual time-frequency Laplace transform technique. The impacts of various parameters on the heat transfer characteristics and nanofluid flow transport with thermal radiation, heat generation/absorption, and nanoparticle volume concentration have been studied through graphs.

Numerical simulation of natural convection within wavy square enclosure filled with nanofluid under magnetic field using EFGM with parallel algorithm

Purpose This paper aims to study the flow and heat transfer inside a wavy enclosure filled with Cu-water nanofluid under magnetic field effect by parallel implemented meshfree approach. Design/methodology/approach The simulation has been carried out for a two-dimensional model with steady, laminar and incompressible flow of the nanofluid filled inside wavy enclosure in which one of the walls is sinusoidal such that the amplitude (A = 0.15) and number of undulations (n = 2) are fixed. A uniform magnetic field B0 has been applied at an inclination angle γ. The governing equations for the transport phenomena have been solved numerically by implementing element-free Galerkin method (EFGM) with the sequential as well as parallel approach. The effect of various parameters, namely, nanoparticle volume fraction (φ), Rayleigh number (Ra), Hartmann number (Ha) and magnetic field inclination angle (γ) has been studied on the natural convection flow of nanofluid. Findings The results are obtained in terms of average Nusselt number calculated at the cold wavy wall, streamlines and isotherms. It has been observed that the increasing value of Rayleigh number results in increased heat transfer rate while the Hartmann number retards the fluid motion. On the other hand, the magnetic field inclination angle gives rise to the heat transfer rate up to its critical value. Above this value, the heat transfer rate starts to decrease. Originality/value The implementation of the magnetic field and its inclination has provided very interesting results on heat and fluid flow which can be used in the drug delivery where nanofluids are used in many physiological problems. Another important novelty of the paper is that meshfree method (EFGM) has been used here because the domain is irregular. The results have been found to be very satisfactory. In addition, parallelization of the scheme (which has not been implemented earlier in such problems) improves the computational efficiency.

Electrohydrodynamics natural convection flow of nanofluids in a rectangular cavity enclosed by a corrugated bottom surface

Electrohydrodynamic enhancement of the laminar natural convection nanofluid flow in a closed cavity is investigated numerically. The bottom wall of the cavity is considered to be a wavy surface and is kept at a high temperature compared to the other flat walls which are maintained at the environment temperature. The electric field is generated from the lower surface which is charged with a uniform voltage of direct current (DC). The interaction of the fluid motion, thermal field, and the electric field for the dielectric nanofluid are formulated using the principles of mass, momentum, and energy conservation along with Maxwell’s and Gauss’s law. A suitable coordinate transformation is used to convert the given set of equations into a form, suitable for the implementation of the finite difference method. Results show that the electric field, induced by the charged particles, significantly influence the flow field within the cavity. It is found that the number of convective cells produced in the flow field depends on the number of waves and their amplitude. For a high nanoparticle volume fraction, the isotherms and the isolines of electric field potential demonstrate two maximum points between two crests of the waves of the bottom surface. On the lower wall, which is directly exposed to the DC current, the isolines for the electric field potential, ϕ, and electric charge density, q, attain their maximum values. However, the distributions for the former physical quantity are distorted, and for the latter they are uniform. Further, a range of electrically charged nanoparticles (Cu, Ag, Al2O3, TiO2, CuO) are tested and it is observed that optimum heat transfer is achieved for Ag–H2O nanofluid.

Thermal radiation impact on MHD heat transfer natural convective nano fluid flow over an impulsively started vertical plate

A numerical model is employed for the nanofluid flow and heat transfer from an infinite vertical plate in the existence of a magnetic field, thermal radiation and viscous dissipation. The solution of the basic governing equations was obtained by the finite element procedure. A collection of nanofluids with a fraction of nanoparticle volume comprising nanoparticles of aluminium oxide, copper, and titanium oxide is included less than or equal to 0.04. With the aid of non-dimensional flow parameters, the mathematical results of velocity and temperature distributions are analysed and shown diagrammatically. It is found that velocity and Temperature profiles enhance by enhancing the value of radiation parameter. The current simulations outlined are relevant for the processing of magnetic nanomaterials in the chemical industry and the metallurgy sector.

Heat transfer enhancement in natural convection flow of nanofluid with Cattaneo thermal transport

Unsteady natural convective flows of nanofluids in a vertical channel with circular cross-section have been investigated using the integral method transforms. The wall temperature on the cylindrical surface is prescribed as a given time-dependent function. The thermal transport is considered of Cattaneo type. Analytical solutions for the fluid temperature and velocity are determined by using the Laplace transform with respect to the time variable and finite Fourier transform with respect to the azimuthal coordinate. The inverse Laplace transforms are obtained using the residues theorem in complex analysis. Solutions in the general case are suitable for particularizations for several azimuthal angles of the channel. As a practical case of these flows, the flow of the alumina-water nanofluid is investigated when the cylindrical surface of the channel is kept at constant temperature. The influence of nanoparticles volume fraction on fluid temperature and velocity is studied. Numerical simulations give optimal values of the nanoparticle volume fraction for the enhancement of the thermal transport. This study would be useful in choosing the optimal value of the nanoparticles volume fraction to improve the thermal transport.

Impact of Lorentz Force and Viscous Dissipation on Unsteady Nanofluid Convection Flow over an Exponentially Moving Vertical Plate

A theoretical analysis has been to draw out the flow characteristics of natural convective nanofluid flow along an exponentially accelerating vertical plate in the presence of magnetic field. Three different types of water-based nanofluids containing copper, silver and copper oxide are considered. The governing equations are transformed into dimensionless form and tackled with the usual time-frequency Laplace transform technique as well as by the Runge Kutta-4th order method with shooting technique. The impacts of various parameters on the heat transfer characteristics and nanofluid flow transportwith joule heating, thermal radiation, heat generation/absorption, and nanoparticle volume concentration have been studied through graphs. It is found that the velocity profiles are remarkably higher when the magnetic force is fixed relative to the plate compared to the fluid.

A 3D numerical study on natural convection flow of nanofluid inside a cubical cavity equipped with porous fins using two-phase mixture model

This paper is concerned with 3D-numerical studies on free convection flow of CuO–water nanofluid in a cubical cavity with porous fins embedded. The two-phase mixture model is employed and the numerical simulations are performed for natural flow of the nanofluid with volume concentrations from 0% to 3% at different Rayleigh (Ra) numbers inside the cavity equipped with 1, 2 and 3 porous fins. Increasing the nanoparticle fraction shows an improvement in heat transfer and Nusselt number. By increment of Ra and domination of convection, the nanofluid flow becomes truly irregular and consequently, the average Nusselt number enhances. For low Ra, isotherms are rather uniform due to weak buoyancy force. While, at higher Rayleigh numbers, augmentation of buoyancy force strongly reduces the isotherms uniformity. In the presence of porous fins, the flow velocity decreases with no significant change in the flow pattern. Also, at low Rayleigh numbers, embedding porous fins results in agitating parallel arrangement of isotherms. The influence of three mentioned variables (i.e., volume fraction, Rayleigh number and number of porous fins) on average Nusselt number is comparatively determined using Taguchi technique and signal to noise ratio according to which nanoparticle loading shows the most principal effect of all.

Finite element simulations for natural convective flow of nanofluid in a rectangular cavity having corrugated heated rods

In this study, numerical simulations of natural convection in a partially heated rectangular cavity containing water-based copper oxide nanofluid (CuO–water) have been carried out. The flow field and heat transfer inside the cavity are influenced by two corrugated heated rods. The governing partial differential equations are transformed to dimensionless coupled nonlinear partial differential equations using some suitable variables. For the thermophysical properties of nanofluid, Koo and Kleinstreuer–Li model is implemented in the governing equation. Numerical solutions of the resulting system of equations are obtained utilizing finite element method. The simulations for flow field and thermal distribution are portrayed in terms of line graphs, streamlines and isotherms. The results are executed for various Rayleigh numbers $$(10^4\le {\mathrm{Ra}} \le 10^6)$$ , nanoparticle volume fractions $$(0.0\le \phi \le 0.2)$$ , amplitudes of the corrugated heated rods $$(0.05\le A_{\mathrm{m}} \le 0.2)$$ and wavelength numbers $$(0 \le n \le 20)$$ . Results depict that the thermal distribution and flow field are getting stronger because of increasing Ra and n. The impact of nanoparticle volume fraction is found to be useful in intensifying the heat transfer rate because of dominant convection. It is worth mentioning that with an increase in $$A_{\mathrm{m}}$$ the thermal distribution in the entire cavity is control by convection.