Solid Volume Fraction Of Nanoparticles Research Articles

Water driven Cu nanoparticles between two concentric ducts with oscillatory pressure gradient

Current study is devoted to examine the magneto-hydrodynamics (MHD) flow of water based Cu Nanoparticles with oscillatory pressure gradient between two concentric cylinders. Arrived broad, it is perceived that the inclusion of nanoparticles has increased considerably the heat transfer near the surface of both laminar and turbulent regimes. Mathematical model is constructed in the form of partial differential equations which contains the effective thermal conductivity and viscosity of base fluid and nanoparticles. Close form solution is attained corresponding to the momentum and energy equation and results are evaluated for velocity, temperature and pressure gradient in the restricted domain. Graphical results for numerical values of the flow control parameters: Hartmann number M, Reynolds number Reω, the solid volume fraction of nanoparticles ϕ and the pulsation parameter based on the periodic pressure gradient have been presented for the pressure difference, frictional forces, velocity profile, temperature profile, and vorticity phenomena have been discussed. The assets of various parameters on the flow quantities of observation are investigated. To the same degree a concluding crux, the streamlines are examined and plotted. The results confirmed that the velocity and temperature may be controlled with the aid of the outside magnetic field and due to the growth in the nanoparticles and considerable enhancement in the heat transfer rate can be found by adding/removing the strength of magnetic field and nanoparticle volume fraction.

Effects of inclination angle and non-uniform heating on mixed convection of a nanofluid filled porous enclosure with active mid-horizontal moving

Inclination angle effects on mixed convection heat transfer in a rectangular porous enclosure filled by Cu-water nanofluid have been numerically analyzed in the present study. Boundary of the enclosure has sinusoidal heating vertical walls, adiabatic horizontal walls and the heated mid-horizontal moving wall. Control volume method is used to discretize the nonlinear governing differential equations. Richardson number (Ri) from 0.01 to 100, Darcy number (Da) from 10−3 to 10−5, inclination angle (γ) from 0° to 90°, solid volume fraction of nanoparticle (φ) from 0.0 to 0.2 and porosity (ε) of the porous medium from 0.4 to 0.8 are discussed and portrayed in the form of streamlines, isotherms, average Nusselt number and velocity graphs. It is observed that the governing flow parameters has significant impact on the fluid flow and temperature distributions. In particular, the features of enclosure inclination, presence of copper nanoparticles in the fluid-saturated porous media and inserting moving wall at the centre of the enclosure are found to enhance the heat transfer rate.

Slip Flow of Nanofluids between Parallel Plates Heated with a Constant Heat Flux

This study investigates the steady fully developed laminar flow and heat transfer of nanofluids between parallel plates heated with a constant heat flux. The governing equations were solved analytically under the boundary conditions of slip velocity and temperature jump. Water was taken as the base fluid and Cu, CuO and Al2O3 as the nanoparticles. The results were obtained for the slip factor in the range of 0 to 0.04, for the Brinkman number in the range of –0.1 to 0.1, for three different values of the ratio of the liquid layering thickness to the particle radius (0.1, 0.2, and 0.4) and for the solid volume fraction ranging from 0 % to 8 %. The results show that the nanoparticle presence in the base fluid has a significant effect on both the velocity field and heat-transfer characteristics. The average Nusselt number increases considerably with the increase of the nanoparticle solid volume fraction. The average Nusselt number takes much higher values for high values of the ratio of the liquid layering thickness to the nanoparticle radius. The average heat transfer rate of nanofluids between parallel plates ranges from the highest to the lowest when Cu, Al2O3, and CuO are used as nanoparticles, respectively.

Critical Analysis of Magnetohydrodynamic Jeffery-Hamel Flow Using Cu-Water Nanofluid

The effects of nanoparticles and magnetic field on the nonlinear Jeffery-Hamel flow using Cuwater nanofluid are analysed in the present study. The basic dimensionless governing equations are solved using power series, which is then analysed by applying a semi-numerical analytical technique called Hermite- Padé approximation. The velocity profiles are presented in convergentdivergent channels for various values of nanoparticles solid volume fraction, Hartmann number, Reynolds number and channel angle. The dominating singularity behavior of the problem is analysed numerically and graphically for nanofluid. The critical relationships among the parameters are also performed qualitatively with the effect of Cu-nanoparticles.GANIT J. Bangladesh Math. Soc.Vol. 34 (2014) 111-126

Numerical study of MHD natural convection inside a sinusoidally heated lid-driven cavity filled with Fe3O4-water nanofluid in the presence of Joule heating

In the present contribution, the conjugate effect of Joule heating and Lorenz force acting on MHD natural convection and entropy generation inside a lid-driven cavity filled with Fe3O4-water nanofluid has been studied numerically. A sinusoidal temperature distribution on both vertical sides is considered, while the horizontal walls are kept adiabatic. The physical problem is represented mathematically by sets of governing partial differential equations and an accurate finite volume method is employed to solve the equations of flow and temperature fields. The study has been carried out for a wide range of Hartmann number Ha=0 to 50, Eckert number Ec=0.025 to 0.075, solid volume fraction ϕ=0 to 0.06, and phase deviation of temperature distribution γ=0 to π. The numerical results for cases with and without internal Joule heating are presented in terms of streamlines, isotherms, average Nusselt number, entropy generation, and Bejan number. The results show that the heat transfer rate reduces with the increase of either Hartmann or Eckert number. In the presence of Joule heating and for all phase deviations, the addition of ferrite nanoparticles to the base fluid improves the heat transfer rate. In addition, the total entropy generation increases with Hartmann and Eckert number as well as the solid volume fraction of nanoparticles.

Numerical Simulation of Nanofluid-Cooling Enhancement of Three Fins Mounted in a Horizontal Channel

This article presents a numerical study of two-dimensional laminar mixed convection in a horizontal channel. The upper horizontal wall of the channel is insulated. The governing equations were solved by using the finite volume method based on the simpler algorithm. Comparisons with previous results were performed and found to be in excellent agreement. The results were presented in terms of streamlines, isotherms, local and average Nusselt numbers for the Richardson number (0 ≤ Ri ≤ 10), Reynolds number (5 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ ϕ ≤ 0.10), and the type of nanofluids (Cu, Ag, Al2O3, and TiO2). The results show that the previous parameters have considerable effects on the flow and thermal fields. It was found that the heat transfer increases with increasing of Ra, Re, and ϕ.

Recovery of drop in heat transfer rate for a rotating system by nanofluids

This paper simulates Al2O3–water nanofluid flow and forced convection around a rotating circular cylinder. The governing parameters are Reynolds number (1≤Re≤100), solid volume fraction of nanoparticles (0≤φ≤0.05) and non-dimensional rotation rate (0≤α≤3). The simulations are performed to study the effects of mentioned parameters on the heat transfer rate and fluid flow characteristics. The governing equations including the continuity, momentum, and energy equations are solved with a finite volume method. It is observed that the reduction of heat transfer with increase in rotation rate is in the vicinity of 6.9% and 32% for Re=5 and 100, respectively at φ=0.05. Furthermore, the augmentation of the heat transfer rate by adding the nanoparticles to the base fluid, water, is in the vicinity of 10.3% at Re=100, φ=0.05 and α=3.

Using artificial neural network to predict thermal conductivity of ethylene glycol with alumina nanoparticle

The correlations of thermal conductivity of alumina nanoparticle dispersed in pure ethylene glycol were proposed by neural network modeling using experimental data. The required input and target data have been taken from the experimental measurement to train artificial neural network (ANN). The temperatures were changed within 24–50 °C. Levenberg algorithm was used to train the ANN. Results showed that the thermal conductivity of nanofluid had a significant increase with increasing solid volume fraction of nanoparticles. The results also revealed that the ANN model can predict the thermal conductivity of Al2O3–EG nanofluid accurately with maximum deviation of 1.3 % and high correlation coefficient (R > 0.998).

Synthesis and characterization of TiO2–water nanofluids with different surfactants

A comprehensive characterization of viscosity, thermal conductivity, surface tension and pH of TiO2–water nanofluid is carried out to investigate the effects of both temperature and solid volume fraction on these thermo-physical properties—nanoparticle solid volume fraction has been varied between 0.1%–2.0% while the temperature ranged from 20 to 60°C. Stability of the synthesized nanoparticle suspension has been investigated with four major surfactants, e.g., cetyl trimethyl ammonium bromide (CTAB), acetic acid (AA), oleic acid (OA) and sodium dodecyl sulfate (SDS) when only CTAB and AA are found to provide stable suspensions. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements indicate particle size ranging between 10 and 40nm and average cluster size of 147nm and 207nm, respectively. The experimental results show that viscosity of TiO2-water based nanofluids increases with solid volume fraction and decreases with temperature. The nanofluids also show slight shear thickening behavior for shear rates ranging between 76 and 760s−1. Thermal conductivity of the nanofluid increases with the increase of both solid volume fraction and temperature. Surface tension of both the AA and CTAB-stabilized nanofluids decreases with solid volume fraction and temperature. The pH of nanofluid is found to remain relatively insensitive to particle loading and temperature.

Unsteady natural convection heat transfer in a nanofluid-filled square cavity with various heat source conditions

Steady and unsteady natural convection heat transfer in a nanofluid-filled square enclosure cavity with various heat source configurations at the bottom were numerically studied using a characteristic-based split scheme finite element method. A wide range of Rayleigh numbers [Formula: see text], solid volume fractions of nanoparticles [Formula: see text], the lengths [Formula: see text], and locations [Formula: see text] of heat sources as well as different types of nanoparticles were considered. Results showed that addition of nanoparticles into the base fluid leads to evident enhancement of heat transfer, particularly at low Rayleigh numbers and that cooling performance is strongly influenced by thermo-physical properties of the nanoparticles. Temporal development of thermal layer in a nanofluid-filled cavity was demonstrated from initial to steady stage through unsteady analysis. We found that the maximum temperature and the average Nusselt number started to oscillate, which is a typical characteristics of high Rayleigh number flow, at higher Rayleigh number in nanofluid than in pure water.

A sensitivity analysis on thermal and pumping power for the flow of nanofluid inside a wavy channel

In this study, a sensitivity analysis is performed by means of surface methodology in order to manage thermal and pumping power for nanofluid flow inside a wavy channel. The governing equations such as 2D steady continuity, momentum, and energy equations have been solved using a finite volume approach. The computational simulations are performed for different Reynolds number (300≤Re≤600), solid volume fractions of nanoparticles (0.01≤φ≤0.05) and channel aspect ratio. The average Nusselt number and the pressure drop ratio are also calculated by numerical experimentation. It was found that the mixing of fluid in wavy channel improves, consequently, the temperature gradient near the wall increases by increasing the amplitude of the wavy wall. The maximum enhancement in Nusselt number with increase in aspect ratio (λ=0.1→0.3) is in the vicinity of 56% for Re=600 and φ=1%, while it is in the vicinity of 24% due to increase in the solid volume fraction (φ=1%→5%)for Re=600 and λ=0.1. Moreover, the non-dimensional pressure drop is more sensitive to the channel aspect ratio rather than the Reynolds number and solid volume fraction. Besides, the sensitivities of average Nusselt number to the Reynolds number and channel aspect ratio increase with increase in the channel aspect ratio.

An experimental study and new correlations of viscosity of ethylene glycol-water based nanofluid at various temperatures and different solid concentrations

This article presents an experimental study on the effect of temperature and solid volume fraction of nanoparticles on the dynamic viscosity for the CuO/EG-water nanofluid. Nanoparticles with diameter of 40 nm are used in the present study to prepare nanofluid by two-step method. A "Brookfield viscometer" has been used to measure the dynamic viscosity of nanofluid with solid volume fraction up to 2% at the temperature range between 20 to <TEX>$60^{\circ}C$</TEX>. The findings have shown that dynamic viscosity of nanofluid increases with increasing particle volume fraction and decreasing temperature. Nine different correlations are developed on experimental data point to predict the relative dynamic viscosity of nanofluid at different temperatures. To make sure of accuracy of the proposed correlations, margin of deviation is presented at the end of this study. The results show excellent agreement between experimental data and those obtained through the correlations.

Mixed convection of nanofluid filled cavity with oscillating lid under the influence of an inclined magnetic field

In this study, mixed convection of an oscillating lid-driven cavity filled with nanofluid under the influence of an inclined uniform magnetic field was numerically investigated. The cavity is heated from below and cooled from above while side walls are assumed to be adiabatic. The top wall velocity varies sinusoidally while no-slip boundary conditions are imposed on the other walls of the cavity. The governing equations was solved by Galerkin weighted residual finite element formulation. The numerical investigation was performed for a range of parameters: Richardson number (10−1≤Ri≤102), Hartmann number (0 ≤ Ha ≤ 60), inclination angle of the magnetic field (0 ≤ γ ≤ 90°), non-dimensional frequency of the oscillating lid (0.001 ≤ St ≤ 1) and solid volume fraction of the nanoparticle (0 ≤ ϕ ≤ 0.04). It is observed that the flow and thermal patterns within the cavity are affected by the variation of these parameters. The heat transfer process becomes inefficient for high Strouhal number, high Hartmann number and high Richardson number. Maximum enhancement of averaged heat transfer and the damping of the convection within the cavity due to the Lorentz forces caused by magnetic field are attained for magnetic inclination angles of γ=90∘ and γ=60∘. As the solid volume fraction of nanoparticles increases averaged heat transfer enhancement of 28.96% is obtained for volume fraction of ϕ=0.04 compared to base fluid.

Numerical Study of Forced Convection of Nanofluid Flow Over a Backward Facing Step With a Corrugated Bottom Wall in the Presence of Different Shaped Obstacles

In this paper, a numerical study of laminar forced convection of nanofluid flow over a backward facing step with a corrugated bottom wall in the presence of different shaped obstacles placed behind the step was performed. The bottom corrugated wall of the channel downstream of the step is isothermally heated and the other walls of the channel and obstacle surface are assumed to be adiabatic. The governing equations are solved with a finite-element method. The influences of the Reynolds number (between 10 and 200), solid volume fraction of the nanoparticle (between 0 and 0.05), and obstacle type (circular, square, and diamond shaped) on fluid flow and heat transfer are numerically investigated. It is observed that among different obstacles, the diamond shaped obstacle provides better local heat transfer enhancement characteristic in the vicinity of the step compared to the circular or square obstacle at high Reynolds number. Heat transfer enhancement of 6.66% is achieved in terms of maximum values with a diamond shaped obstacle compared to the no-obstacle case of the corrugated channel. Adding an obstacle deteriorates heat transfer in terms of average values for the backward facing step geometry with a corrugated wall. When the solid volume fraction of nanoparticle is increased, maximum and average heat transfer rate increase. Heat transfer enhancements of 7.45%, 7.42%, 6.94%, and 6.64% are obtained for the average values for circle, diamond, square, and no-obstacle cases, respectively, when solid volume fraction of 0.05 is compared to pure fluid.

Magnetohydrodynamic Stability of Jeffery-Hamel Flow using Different Nanoparticles

The effects of nanoparticles and magnetic field on the nonlinear Jeffery-Hamel flow of Cu-water nanofluid are analyzed in the present study. The aThe effects of three different nanoparticles and magnetic field on the nonlinear Jeffery-Hamel flow of water based nanofluid are analyzed in the present study. The basic dimensionless governing equations are solved using series solution which are then analysed to inspect the instability of the problem by a semi-numerical analytical technique called Hermite- Padé approximation. The velocity profiles are presented in convergentdivergent channels for various values of nanoparticles solid volume fraction, Hartmann number, Reynolds number and channel angle. The dominating singularity behavior of the problem is analysed numerically and graphically. The critical relationships among the parameters are also performed qualitatively to observe the behavior of the various nanoparticles.basic dimensionless governing equations are solved using series solution which are then analysed to inspect the instability of the problem by a semi-numerical analytical technique called Hermite- Padé approximation. The velocity profiles are presented in convergent-divergent channels for various values of nanoparticles solid volume fraction, Hartmann number, Reynolds number and channel angle. The dominating singularity behavior of the problem is analysed numerically and graphically. The critical relationships among the parameters are also performed qualitatively to observe the behavior of the nanoparticles.

Study of natural convection cooling of a nanofluid subjected to a magnetic field

This paper presents a numerical study of natural convection cooling of water-Al2O3 nanofluid by two heat sinks vertically attached to the horizontal walls of a cavity subjected to a magnetic field. The left wall is hot, the right wall is cold, while the horizontal walls are insulated. Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature fields. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number of the base fluid, Ra=103 to 105, Hartmann number varied from Ha=0 to 60 and the solid volume fraction of nanoparticles between ϕ=0 and 6%. In order to investigate the effect of heat sinks location, three different configurations of heat sinks are considered. The effects of Rayleigh numbers, Hartmann number and heat sinks location on the streamlines, isotherms, Nusselt number are investigated. Results show that the heat transfer rate decreases with the increase of Hartmann number and increases with the rise of Rayleigh number. In addition it is observed that the average Nusselt number increases linearly with the increase of the nanoparticles solid volume fraction. Also, results show that the heat sinks positions greatly influence the heat transfer rate depending on the Hartmann number, Rayleigh number and nanoparticle solid volume fraction.

Numerical study of natural turbulent convection of nanofluids in a tall cavity heated from below

In the present paper a numerical study of natural turbulent convection in a tall cavity filled with nanofluids. The cavity has a heat source embedded on its bottom wall, while the left, right and top walls of the cavity are maintained at a relatively low temperature. The working fluid is a water based nanofluid having three nanoparticle types: alumina, copper and copper oxid. The influence of pertinent parameters such as Rayleigh number, the type of nanofluid and solid volume fraction of nanoparticles on the cooling performance is studied. Steady forms of twodimensional Reynolds-Averaged-Navier-Stokes equations and conservation equations of mass and energy, coupled with the Boussinesq approximation, are solved by the control volume based discretisation method employing the SIMPLE algorithm for pressure-velocity coupling. Turbulence is modeled using the standard k-? model. The Rayleigh number, Ra, is varied from 2.491009 to 2.491011. The volume fractions of nanoparticles were varied in the interval 0??? 6% . Stream lines, isotherms, velocity profiles and Temperature profiles are presented for various combinations of Ra, the type of nanofluid and solid volume fraction of nanoparticles. The results are reported in the form of average Nusselt number on the heated wall. It is shown that for all values of Ra, the average heat transfer rate from the heat source increases almost linearly and monotonically as the solid volume fraction increases. Finally the average heat transfer rate takes on values that decrease according to the ordering Cu, CuO and Al2O3.

Three dimensional numerical analysis of natural convection cooling with an array of discrete heaters embedded in nanofluid filled enclosure

This study deals with the numerical analysis of 3D natural convection equipment cooling with a 3×3 array of isothermal heaters mounted on one vertical wall of the nanofluid filled enclosure. The enclosure is filled with water based nanofluid containing Copper (Cu) or Alumina (Al2O3) nanoparticles. The transport equations are solved by the finite volume method based on the SIMPLE algorithm with power-law scheme. The influence of pertinent parameters such as Rayleigh number (105⩽Ra⩽107), nanoparticle volume fraction (0%⩽ϕ⩽10%) and enclosure side aspect ratio (1.0⩽AS⩽7.5) on the fluid flow and heat transfer characteristics are investigated together with different nanofluids and enclosure boundary conditions. It is observed that Cu–water nanofluid has the greatest effect on the equipment cooling performance compared with Al2O3–water nanofluid. Moreover, the row averaged Nusselt number increases monotonically with increase in both the Rayleigh number and the nanoparticle solid volume fraction.

Opposition of Magnetohydrodynamic and AL2O3–water nanofluid flow around a vertex facing triangular obstacle

This article is an attempt to enhance the heat transfer rate around an obstacle by nanofluids and control the instabilities of the unsteady flow by Magnetohydrodynamics. The finite volume method (FVM) is used to simulate the AL2O3–water nanofluid flow around a triangular obstacle. An external magnetic field is used to study the effects of magnetic field on fluid flow and heat transfer. The range of Stuart number and solid volume fraction of nanoparticles are 0–10 and 0–0.05, respectively. Also, the Reynolds number is fixed at Re=100. The effects of above parameters on the flow and heat transfer characteristics are investigated. The obtained results indicate that a stronger magnetic field is needed for vanishing the recirculation wake and stabilizing the flow in nanofluid comparing with the clear fluid. Also, the effect of magnetic field on reduction of heat transfer increases with increase in solid volume fractions.

On three-dimensional flow of nanofluids past a convectively heated deformable surface: A numerical study

This paper is concerned with the three-dimensional rotating flow of nanofluid induced by a convectively heated deformable surface. The base fluid is treated as water while three different types of nanoparticles namely copper oxide-CuO, copper-Cu and silver-Ag are analyzed. Two different models for effective thermal conductivity of nanofluids are employed. A self-similar form of the governing differential system is formulated via adequate transformations. Shooting approach combined with fifth order Runge–Kutta method is used to determine the velocity and temperature distributions above the sheet. Our computations reveal that skin friction coefficient has direct relationship with the volume fraction of nanoparticles. Further the surface heat transfer rate is an increasing function of the solid volume fraction of nanoparticles. Sketch for three-dimensional streamlines is also obtained and discussed for a particular case.