Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
3
1
2000
A Comparison of Thermal Performances of Underground Power Cables in Dry and Saturated Soils
A model to study the thermal and fluid dynamics behavior of a system made of directly buried electrical cable in a dry or saturated soil is presented. The governing equations are solved via the finite difference method. Different evaluations are carried out assuming different characteristics for the soil and for the electrical loads. The dimensionless results include a comparison between the thermal resistance of dry and saturated soil as well as the functional link between the thermal resistivity of the soil, ρt, evaluated by means of the IEC 287 standard and the dimensionless parameters of the model proposed by the authors. Finally, a correlation for the Nusselt number is determined exclusively in relation to the design data.
Alberto
Carotenuto
Dipartimento di Meccanica Strutture Ambiente e Territorio (Di. M. S. A. T.), Università di Cassino, Via Di Biasio 43, 03043 Cassino, Italy ; and University of Naples "Parthenope", Naples, Italy
G.
Buonanno
Dipartimento di Meccanica Strutture Ambiente e Territorio (Di. M. S. A. T.), Università di Cassino, Via Di Biasio 43, 03043 Cassino, Italy
1-10
Double-Diffusive Convection in Slender Anisotropic Porous Enclosures
This article reports an analytical solution for steady natural convection in a slender rectangular porous cavity with hydrodynamic, thermal, and solute anisotropy, and uniform flux of heat and mass on the vertical sides. The principal directions of the permeability, thermal diffusivity, and solute diffusivity tensors are taken independently oblique to the gravity vector. The assumptions inherent in the derivation of the analytical solution are validated by comparison with numerical solutions. The analytical solution is shown to be valid for aspect ratio beyond 3. A limited parametric analysis is also performed. The effect of the anisotropic parameters (K*, α*, D*, θ1, θ2, and θ3) are seen to be marked.
P.
Bera
Department of Mathematics, Institute of Engineering and Technology, Kanpur University, India 208016
P.
Singh
Department of Mathematics, Indian Institute of Technology, Kanpur, India
Vinayak
Eswaran
Department of Mechanical Engineering, IIT Hyderabad, Yeddumailaram-502 205, Andhra Pradesh, India
11-29
Vertical Free Convective Boundary-Layer Flow in a Porous Medium Using a Thermal Nonequilibrium Model
In this article we study the effect of adopting a two-temperature model of microscopic heat transfer on the classical Cheng and Minkowycz (1977) vertical free convection boundary-layer flow in a porous medium. Such a model, which allows the solid and fluid phases not to be in local thermal equilibrium, is found to modify substantially the behavior of the flow relatively close to the leading edge, where the boundary layer is comprised of two distinct asymptotic regions. The numerical simulation of the developing boundary-layer relies heavily on near-leading-edge analysis to provide suitable boundary conditions. At increasing distances from the leading edge the difference between the temperatures of the fluid and solid phases decreases to zero, which corresponds to thermal equilibrium between the phases; this is confirmed by an asymptotic analysis.
D. Andrew S.
Rees
Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
Ioan
Pop
Department of Applied Mathematics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
31-44
Basic Fluid Flow Problems in Porous Media
This article presents analytical solutions for different basic fluid flow problems in porous media. The fluid problems under investigation include: (1) transient flow in porous tubes and annuli, (2) transient flow in porous slabs with suction and injection, (3) rotating liquid in porous cylindrical and annular containers, (4) steady asymptotic suction flow in a porous domain, and (5) free-convection flow in porous slabs confined between heated plates.
Moh'd Ahmad
Al-Nimr
Jordan University of Science and Technology
M. K.
Alkam
Department of Mechanical Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan
45-59
Oscillatory Motion of a Viscoelastic Fluid over a Stretching Sheet in Porous Media
The effects of an oscillatory motion of a viscoelastic fluid over infinite stretching sheet in porous media have been studied. The surface absorbs the fluid with a porous medium, and the velocity oscillates depending on the stretching rate (b) and the vertical distance (z). Analytical expressions for the velocity and coefficient of skin friction have been studied, first by the perturbation technique and then by Taylor series method. The effect of viscoelastic parameter (K1), permeability parameter (K2), and the vertical distance (z) on the velocity and on the flow characteristics are discussed. The velocity of the viscoelastic fluid is found to decrease in the presence of porous media, as compared to the viscous fluid.
K. V.
Prasad
Department of Mathematics, Central College Campus, Bangalore University, Bangalore, India
M. Subhas
Abel
Department of Mathematics, Gulbarga University, Gulbarga, Kamataka, India
Ambuja
Joshi
Department of Mathematics, Gulbarga University, Gulbarga Karnataka, India
61-68
Thermofluid Analysis of Entrance Section of a Continuous Pressure Infiltration Process for Fiber-Metal Matrix Composites
Recently a continuous process has been developed for manufacturing wires made of a fiber-reinforced metal matrix composite. In the process a fiber preform is fed continuously into a high-pressure crucible containing molten metal for melt infiltration, and comes out as composite wire. A series of tests show that there exists a range of process speed in which the composite wire is produced smoothly without any leakage of melt. A thermofluid model is developed to understand the most crucial part of the system, the entrance gate section to the crucible. The model prediction agrees well with our test observations of the process.
Uichiro
Narusawa
Department of Mechanical, Industrial & Manufacturing Engineering, Northeastern University, Boston, MA 02115, USA
J. T.
Blucher
Department of Mechanical, Industrial & Manufacturing Engineering, Northeastern University, Boston, MA 02115, USA
69-78
Natural Convection in Tilted Porous Enclosures in the Presence of a Transverse Magnetic Field
A numerical study has been conducted on laminar natural convection heat transfer in a tilted square enclosure filled with a fluid-saturated porous medium in the presence of a transverse magnetic field. The vertical walls of the enclosure are maintained at constant temperatures while the horizontal walls are thermally insulated. The flow in the porous region is modeled using Darcy's law and the Boussinesq approximation. The control-volume finite difference method is used to solve the governing equations for different values of Darcy-Rayleigh number, Hartmann number, and inclination angle. The numerical results obtained are presented graphically in terms of streamlines and isotherms to illustrate interesting features of the solution. A new correlation for the average Nusselt number is developed in terms of Darcy-Rayleigh number and Hartmann number in vertical cavities. Typical numerical results showed excellent agreement of the present approach with the available data in the literature.
Khalil
Khanafer
Mechanical Engineering Department, Australian College of Kuwait, Kuwait
N. M.
Al-Najem
Department of Mechanical and Industrial Engineering, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
M. M.
El-Refaee
Department of Mechanical and Industrial Engineering, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
79-91
Boundary Layer Flow of a Micropolar Fluid Through a Porous Medium
A.
Raptis
Department of Mathematics, University of Ioannina, Ioannina 451 10, Greece
95-97