The Cheng–Minkowycz problem for the double-diffusive natural convective boundary layer flow in a porous medium saturated by a nanofluid
TL;DR: In this article, an analytical treatment of double-diffusive nanofluid convection in a porous medium is presented, where the base fluid is itself a binary fluid such as salty water.
About: This article is published in International Journal of Heat and Mass Transfer.The article was published on 2011-01-15. It has received 220 citations till now. The article focuses on the topics: Nanofluid & Natural convection.
Citations
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TL;DR: In this article, a review of the literature on entropy generation due to flow and heat transfer of nanofluids in different geometries and flow regimes is presented, and some suggestions for future work are presented.
416 citations
TL;DR: In this paper, a comprehensive review is conducted on the simultaneous application of nanofluids and porous media for heat transfer enhancement purposes in thermal systems with different structures, flow regimes, and boundary conditions.
333 citations
Cites background or methods from "The Cheng–Minkowycz problem for the..."
...Also, for the double-diffusive natural convective boundary layer flow the thermal energy equations were included regular diffusion and cross-diffusion terms [49]....
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...Thermal instability in a porous medium saturated by nanofluid Beside the comprehensive studies of thermal instability in a porous medium layer for investigation on the onset of convection by Nield and Kuznetsov [11,44,45,47], a similar study was also considered by other researchers....
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...Investigations on convection heat transport past a horizontal plate in a porous medium saturated by nanofluid are done by a few researchers such as Nield and Kuznetsov [11,44–47] and Bhadauria et al. [48]....
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...Later, Nield and Kuznetsov [46] studied the effect of local thermal non-equilibrium on the onset of convection....
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...The onset of double-diffusive convection of salty water-based nanofluids in a horizontal layer of a porous medium is examined by Nield and Kuznetsov [44]....
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TL;DR: In this article, the effects of magnetohydrodynamics (MHD) and elasticity on the flow are considered, and the effect of nanoparticles are also investigated Similarity transformations are presented to convert the governing nonlinear partial differential equation into coupled ordinary differential equations.
Abstract: In the present article, two dimensional boundary-layer flows and the heat transfer of a Maxwell fluid past a stretching sheet are studied numerically The effects of magnetohydrodynamics (MHD) and elasticity on the flow are considered Moreover, the effects of nanoparticles are also investigated Similarity transformations are presented to convert the governing nonlinear partial differential equation into coupled ordinary differential equations The reduced boundary layer equations of the Maxwell nanofluid model are solved numerically The effects of the emerging parameters, namely, the magnetic parameter M, the elastic parameter K, the Prandtl parameter Pr, the Brownian motion Nb, the thermophoresis parameter Nt and the Lewis number Le on the temperature and the concentration profile are discussed Interesting results are shown graphically The skin friction coefficient, the dimensionless heat transfer rate and the concentration rate are also plotted against the flow control parameters
227 citations
TL;DR: In this article, the authors summarize the published articles in respect to porosity, permeability (K) and inertia coefficient (Cf) and effective thermal conductivity (keff) for porous media, also on the thermophysical properties of nanofluid and the studies on convection heat transfer in porous media with nanoparticles having dimensions of (1-100) nm.
Abstract: There are two advantages of using porous media. First, its dissipation area is greater than the conventional fins that enhances the heat convection. Second is the irregular motion of the fluid flow around the individual beads which mixes the fluid more effectively. Nanofluids result from the mixtures of base fluid with nanoparticles having dimensions of (1–100) nm, with very high thermal conductivities; as a result, it would be the best convection heat transfer by using two applications together: porous media and nanofluids. This article aims to summarize the published articles in respect to porosity, permeability (K) and inertia coefficient (Cf) and effective thermal conductivity (keff) for porous media, also on the thermophysical properties of nanofluid and the studies on convection heat transfer in porous media with nanofluid.
213 citations
TL;DR: This work studies the flow and heat transfer characteristics of a viscous nanofluid over a nonlinearly stretching sheet in the presence of thermal radiation, included in the energy equation, and variable wall temperature.
Abstract: In this work, we study the flow and heat transfer characteristics of a viscous nanofluid over a nonlinearly stretching sheet in the presence of thermal radiation, included in the energy equation, and variable wall temperature. A similarity transformation was used to transform the governing partial differential equations to a system of nonlinear ordinary differential equations. An efficient numerical shooting technique with a fourth-order Runge-Kutta scheme was used to obtain the solution of the boundary value problem. The variations of dimensionless surface temperature, as well as flow and heat-transfer characteristics with the governing dimensionless parameters of the problem, which include the nanoparticle volume fraction ϕ, the nonlinearly stretching sheet parameter n, the thermal radiation parameter NR, and the viscous dissipation parameter Ec, were graphed and tabulated. Excellent validation of the present numerical results has been achieved with the earlier nonlinearly stretching sheet problem of Cortell for local Nusselt number without taking the effect of nanoparticles.
208 citations
Cites background from "The Cheng–Minkowycz problem for the..."
...Furthermore, Nield and Kuznetsov [24,25] have studied the Cheng and Minkowycz [26] problem of natural convection past a vertical plate in a porous medium saturated by a nanofluid....
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...Nield DA, Kuznetsov AV: The Cheng-Minkowycz problem for natural convective boundary-layer flow in a porous medium saturated by a nanofluid....
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...Very recently, Kuznetsov and Nield [23] have examined the influence of nanoparticles on natural convection boundary-layer flow past a vertical plate using a model in which Brownian motion and thermophoresis are accounted for....
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...Nield DA, Kuznetsov AV: The Cheng-Minkowycz problem for the doublediffusive natural convective boundary-layer flow in a porous medium saturated by a nanofluid....
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...Kuznetsov AV, Nield DA: Natural convective boundary-layer flow of a nanofluid past a vertical plate....
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References
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Book•
01 Jan 1992TL;DR: In this paper, an introduction to convection in porous media assumes the reader is familiar with basic fluid mechanics and heat transfer, going on to cover insulation of buildings, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering and the storage of heat-generating materials like grain and coal.
Abstract: This introduction to convection in porous media assumes the reader is familiar with basic fluid mechanics and heat transfer, going on to cover insulation of buildings, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering and the storage of heat-generating materials like grain and coal. Geophysical applications range from the flow of groundwater around hot intrusions to the stability of snow against avalanches. The book is intended to be used as a reference, a tutorial work or a textbook for graduates.
5,570 citations
TL;DR: In this article, the authors considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid and concluded that only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids.
Abstract: Nanofluids are engineered colloids made of a base fluid and nanoparticles (1-100 nm) Nanofluids have higher thermal conductivity' and single-phase heat transfer coefficients than their base fluids In particular the heat transfer coefficient increases appear to go beyond the mere thermal-conductivity effect, and cannot be predicted by traditional pure-fluid correlations such as Dittus-Boelter's In the nanofluid literature this behavior is generally attributed to thermal dispersion and intensified turbulence, brought about by nanoparticle motion To test the validity of this assumption, we have considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid These are inertia, Brownian diffusion, thermophoresis, diffusioplwresis, Magnus effect, fluid drainage, and gravity We concluded that, of these seven, only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids Based on this finding, we developed a two-component four-equation nonhomogeneous equilibrium model for mass, momentum, and heat transport in nanofluids A nondimensional analysis of the equations suggests that energy transfer by nanoparticle dispersion is negligible, and thus cannot explain the abnormal heat transfer coefficient increases Furthermore, a comparison of the nanoparticle and turbulent eddy time and length scales clearly indicates that the nanoparticles move homogeneously with the fluid in the presence of turbulent eddies so an effect on turbulence intensity is also doubtful Thus, we propose an alternative explanation for the abnormal heat transfer coefficient increases: the nanofluid properties may vary significantly within the boundary layer because of the effect of the temperature gradient and thermophoresis For a heated fluid, these effects can result in a significant decrease of viscosity within the boundary layer, thus leading to heat transfer enhancement A correlation structure that captures these effects is proposed
5,329 citations
TL;DR: In this article, an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat-transfer fluids, which are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluid, and they represent the best hope for enhancing heat transfer.
Abstract: Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.
4,634 citations
Book•
01 Jan 1984
TL;DR: In this paper, the authors describe a transition from Laminar boundary layer flow to Turbulent Boundary Layer flow with change of phase Mass Transfer Convection in Porous Media.
Abstract: Fundamental Principles Laminar Boundary Layer Flow Laminar Duct Flow External Natural Convection Internal Natural Convection Transition to Turbulence Turbulent Boundary Layer Flow Turbulent Duct Flow Free Turbulent Flows Convection with Change of Phase Mass Transfer Convection in Porous Media.
4,067 citations
TL;DR: A review on fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows is presented in this article, where the authors identify opportunities for future research.
1,988 citations