In this study, three dimensional nanofluid flow and heat transfer in a rotating system in the presence of magnetic field is investigated. The important effects of Brownian motion and thermophoresis have been included in the model of nanofluid. The basic partial differential equations are reduced to ordinary differential equations which are solved numerically using the fourth-order Runge–Kutta method. The numerical investigation is carried out for different governing parameters namely: Reynolds number, Rotation parameter, Magnetic parameter, Schmidt number, Thermophoretic parameter and Brownian parameter. Results indicate that skin friction parameter increases with augment of Reynolds number, Rotation parameter and Magnetic parameter. Also it can be found that Nusselt number has a direct relationship with Reynolds number while it has a reverse relationship with Rotation parameter, Magnetic parameter, Schmidt number, Thermophoretic parameter and Brownian parameter.
Purpose Nanofluid flow which is squeezed between parallel plates is studied using differential transformation method (DTM). The fluid in the enclosure is water containing different types of nanoparticles: Al 2 O 3 and CuO. The effective thermal conductivity and viscosity of nanofluid are calculated by Koo–Kleinstreuer–Li (KKL) correlation. The comparison between the results from DTM and numerical method are in well agreement which proofs the capability of this method for solving such problems. Effects of the squeeze number and nanofluid volume fraction on flow and heat transfer are examined. Results indicate that Nusselt number augment with increase of the nanoparticle volume fraction. Also, it can be found that heat transfer enhancement of CuO is higher than Al 2 O 3 . Design/methodology/approach The problem of nanofluid flow which is squeezed between parallel plates is investigated analytically using DTM. The fluid in the enclosure is water containing different types of nanoparticles: Al 2 O 3 and CuO. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL correlation. In this model, effect of Brownian motion on the effective thermal conductivity is considered. The comparison between the results from DTM and numerical method are in well agreement which proves the capability of this method for solving such problems. The effect of the squeeze number and the nanofluid volume fraction on flow and heat transfer is investigated. The results show that Nusselt number increase with increase of the nanoparticle volume fraction. Also, it can be found that heat transfer enhancement of CuO is higher than Al 2 O 3 . Findings The effect of the squeeze number and the nanofluid volume fraction on flow and heat transfer is investigated. The results show that Nusselt number increase with increase of the nanoparticle volume fraction. Also, it can be found that heat transfer enhancement of CuO is higher than Al 2 O 3 . Originality/value This paper is original.
In the present numerical prediction of the deposition rate of silicon from silane in a CVD process, the conservation equations for mass, momentum, energy, and chemical species are solved on a staggered grid using the SIMPLE algorithm, while the rate of chemical reactions in the gas phase and on the susceptor surface is obtained from an Arrhenius rate equation. Predicted deposition rates as a function of position along the susceptor with and without the gas phase chemical reaction are compared with the available experimental and numerical data; agreement is excellent except at the leading edge of the susceptor, where the deposition rate is overpredicted.
No abstract is provided for this article.
Numerical analysis is provided to determine the impact of inserting multi-channel twisted tape on hydrothermal characteristics of nanomaterial in a solar system. Testing fluid is Al2O3–water nanofluid and homogeneous model is offered to estimate its behavior. Computational modeling was presented for different number of channel and revolution, Reynolds number and diameter ratio. Outputs reveal that there is a direct proportionality between Re and temperature gradient. Greater centrifugal force can be generated with augment of N. Stronger rotation flow occurs for greater diameter ratio. Thermal performance has reverse relationship with Re and n. Maximum values of η is 1.08 which is related for case of n = 2, Re = 4000, N = 7, D* = 0.14.
In this article, Control volume based finite element method (CVFEM) is employed to simulate magnetohydrodynamic (MHD) nanofluid convective heat transfer through a porous cavity by means of thermal non-equilibrium model. Nanofluid properties are estimated by means of Koo–Kleinstreuer–Li (KKL) model and Darcy–Boussinesq approximation is employed for momentum equation. Numerical simulations are provided to find the effects of Rayleigh number R a , solid–nanofluid interface heat transfer parameter N h s , Hartmann number H a and porosity ε . Outputs depict that velocity augments with increase of N h s while it increases with augment of Rayleigh number. Temperature gradient reduces with augment of porosity.
The study of convective heat transfer in fluid-saturated porous media has many important applications in technology geothermal energy recovery, such as oil recovery, food processing, fiber and granular insulation, porous burner and heater, combustion of low-calorific fuels to diesel engines, and design of packed bed reactors. Also the flow in porous tubes or channels has been under considerable attention in recent years because of its various applications in biomedical engineering, transpiration cooling boundary layer control, and gaseous diffusion. Nanofluids are produced by dispersing the nanometer-scale solid particles into base liquids with low thermal conductivity, such as water, ethylene glycol, oils. In this chapter, nanofluid hydrothermal behavior in porous media has been investigated.
The three-dimensional problem of steady fluid deposition on an inclined rotating disk is illustrated in this study. The governing non-linear partial differential equations are reduced to the nonlinearordinarydifferentialequationssystembysimilaritytransform.Theanalyticalsolutionapplied tosolvethissystemistheHomotopyPerturbationMethod(HPM).Thevelocityandtemperatureprofiles areshownandtheinfluenceofPrandtlnumberandrotationratioontheflowfieldandtheNusseltnumber arediscussedindetail.Thevalidityofoursolutionsisverifiedbythenumericalresults. '2012SharifUniversityofTechnology.ProductionandhostingbyElsevierB.V.Allrightsreserved.
In current article, Lorentz forces influence on NEPCM solidification phenomena in a storage porous unit is reported with numerical method via FEM. Nanotechnology and magnetic field are employed to expedite this unsteady process. Roles of Hartmann number, Rayleigh number and volume fraction of NEPCM have been reported. Outputs reveal that solid fraction rises in presence of Lorentz forces. Full discharging time reduces with augment of volume fraction of CuO-water and Hartmann number.
Effect of Lorentz forces on natural convection in a complex shaped cavity filled with nanoliquid immersed in porous medium is investigated by means of Control volume based finite element method (CVFEM). Non Darcy model is taken into account for porous media. The working fluid is Fe3O4 –water and its viscosity considered as function of magnetic field. Figures are illustrated for different values of Darcy number (Da), Fe3O4 -water volume fraction (ϕ), Rayleigh (Ra) and Hartmann (Ha) numbers. Results depict that enhancing in Lorentz forces results in reduce in nanofluid motion and increase the thickness of thermal boundary. Convective heat transfer enhances with rise of Darcy number.
In this work, the effect of a variable spatial magnetic field on ferro-nanofluid flow and heat transfer in a double-sided lid-driven enclosure with a sinusoidal hot wall is investigated. The working fluid is a mixture of iron oxide (Fe3O4) nanoparticles and water and is referred to as a ferro-nanofluid. The control volume-based finite element method (CVFEM) is used to solve the governing equations in the stream function–vorticity formulation. In deriving the governing equations for this investigation, the effect of both ferro-hydrodynamics and magneto-hydrodynamics is taken into account. The numerical calculations are performed for different governing parameters namely; the Reynolds number, nanoparticle volume fraction, magnetic number (arising from Ferrohydrodynamics (FHD) consideration), and the Hartmann number (arising from Magnetohydrodynamics (MHD) consideration). The results show that an enhancement in heat transfer has a direct relationship with the Reynolds number and the Hartmann number, but it has an inverse relationship with the magnetic number. Also, it can be concluded that the Nusselt number increases with the increase of the nanoparticle volume fraction, magnetic number, and the Reynolds number while the opposite trend is observed for the Hartmann number.
In this paper, MHD effect on natural convection heat transfer in an inclined L-shape enclosure filled with nanofluid is studied. The numerical investigation is carried out using the control volume based finite element method (CVFEM). The fluid in the enclosure is a water-based nanofluid containing Al2O3 nanoparticle. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL (Koo–Kleinstreuer–Li) correlation in which effect of Brownian motion on the effective thermal conductivity is considered. The heat transfer between cold and hot regions of the enclosure cannot be well understood by using isotherm patterns so heatline visualization technique is used to find the direction and intensity of heat transfer in a domain. Effect of Hartmann number, volume fraction of nanoparticle, Rayleigh number and inclination angle on streamline, isotherm and heatline are examined. The results show that Nusselt number increases with increase of Rayleigh number and volume fraction of nanoparticle while it decreases with augment of Hartmann number and inclination angle. Enhancement in heat transfer has reverse relationship with Hartmann number and Rayleigh number.
In this study, free convection heat transfer in an enclosure filled with nanofluid is investigated. The important effects of Brownian motion and thermophoresis have been included in the model of nanofluid. Control volume based finite element method is used to solve the governing equations. Effects of angle of turn, buoyancy ratio number and Lewis number on streamline, isotherm and isoconcentration are considered. Also a correlation for Nusselt number corresponding to active parameters is presented. Results indicated that Nusselt number is an increasing function of buoyancy ratio number while it is a decreasing function of Lewis number and angle of turn. Also it can be found that Lewis number has no significant effect on Nusselt number at low values of buoyancy ratio number.
In current modeling, turbulent heat transfer of homogeneous nanofluid due to inserting double twisted tapes has been carried out. To better describing performance of unit, generation of entropy has been examined. CuO nanomaterial has been dispersed in to H2O, to help its conductivity. The pipe was under the impact of uniform heat flux. Equations describing the flow and energy balance were solved applying finite volume method. The simulations illustrate that both augmenting pumping power and height of tape result in the reduction of thermal component and the augmentation of frictional component.
Magnetic field effect on CuO–water nanofluid flow and heat transfer in an enclosure which is heated from below is investigated. Lattice Boltzmann method is applied to solve the governing equations. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL (Koo–Kleinstreuer–Li) correlation. In this model effect of Brownian motion on the effective thermal conductivity is considered. Effect of active parameter such as: Hartmann number, heat source length, nanoparticle volume fraction and Rayleigh numbers on the flow and heat transfer characteristics have been examined. The results reveal that the enhancement in heat transfer increases as Hartmann number and heat source length increase but it decreases with increase of Rayleigh number. Also it can be found that effect of Hartmann number and heat source length is more pronounced at high Rayleigh number.
No abstract is provided for this article.
Nanofluid heat transfer augmentation in a heat exchanger equipped with helical twisted tape turbulator is simulated numerically via Finite volume method. Impacts of width ratio, Reynolds number and pitch ratio on nanofluid hydrothermal behavior were illustrated. Related formulas for Nusselt number and Darcy factor are provided according to obtained results. Outputs show that thermal boundary layer thickness decreases with augment of width ratio due to stronger secondary flow. Better nanofluid mixing can be obtained for lower values of pitch ratio.
In this study natural convection heat transfer in a cold outer circular enclosure containing a hot inner sinusoidal cylinder is investigated numerically using the Control Volume based Finite Element Method (CVFEM). Both circular enclosure and inner cylinder are maintained at constant temperature and air filled the enclosure. The governing equations of fluid motion and heat transfer in their vorticity stream function form are used to simulate the fluid flow and heat transfer. The calculations were performed for different governing parameters such as the Rayleigh number (Ra = 103, 104, 105 and 106), values of amplitude (A = 0.1, 0.3 and 0.5) and the number of undulations of the inner cylinder (N = 2, 3, 5 and 6). The results show that streamlines, isotherms, and the number, size and formation of the cells inside the enclosure strongly depend on the Rayleigh number, values of amplitude and the number of undulations of the enclosure.
