Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
9
4
2006
Experimental Investigation of the Diffusion Coefficients in Porous Media by Application of X-Ray Computer Tomography
The present work describes a new experimental method that makes it possible to investigate diffusion coefficients in a porous medium. The method is based on application of X-ray computed tomography (CT). The general applicability of this method for the determination of diffusion coefficients is demonstrated. A series of such experiments was carried out. Several samples of carbonaceous and sandstone rock were investigated. The diffusion coefficients in porous media were determined by measuring the concentration of salt in different slices of a sample as a function of time. In cases where stable values of diffusion coefficients were obtained (all samples except for one highly heterogeneous sample), these values served for the determination of the tortuosity-porosity factors for a given type of porous medium.
P. V.
Zhelezny
Statoil ASA, ST-FV-C3, Svanholmen 6, 4035, Stavanger, Norway
A. A.
Shapiro
A.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkiv 61085, Ukraine
275-288
Numerical Study of Heat Transfer in a Porous Pipe Subjected to Reciprocating Flow
A numerical investigation has been carried out for laminar incompressible reciprocating flow and heat transfer in a pipe filled with a porous medium and with a finite length. The pipe walls are assumed at constant temperature. A general model for the momentum equation was employed. The model for the energy transport was based on the local thermal equilibrium assumption between the fluid and the solid phases. The control-volume-based finite element method is used for solving the differential system equations with an unequal order velocity-pressure interpolation. A comprehensive analysis of the influence of the Darcy number, the kinetic Reynolds number, the thermal conductivity ratio, the heat capacity ratio, and the dimensionless oscillation amplitude Ao is presented.
Dhahri
Hacen
National school of Engineers Laboratory of Thermal and Energy Systems Studies Monastir University, Ibn Eljazzar Street, 5019 Monastir, Tunisia
A.
Boughamoura
Laboratoire d'Etudes des Systèmes Thermiques et Energétiques, Ecole Nationale d'Ingénieurs de Monastir, Rue Ibn Eljazzar, 5019 Monastir, Tunisie
Sassi Ben
Nasrallah
Laboratoire d'Études des Systèmes Thermiques et Énergétiques, Ecole Nationale d'Ingénieurs
de Monastir, Monastir 5019 Tunisie
289-305
Scale Analysis of Electrodiffusion Through Porous Media
This paper is a fundamental analytical and numerical study of the electrical current effect on the diffusion of ions through porous media. The analytical part is based on scale analysis in the limit where the electrical current is the dominant drive force for ionic diffusion The scales of this regime are compared with the known scales of pure diffusion, where the dominant drive force is the concentration gradient. The new dimensionless group B that marks the transition between classical diffusion and electrodiffusion is identified: B is the ratio of the two characteristic time scales, the time of electrodiffusion divided by the time of pure diffusion. The numerical part is based on the Nernst-Planck equation for continuity, which is nondimensionalized based on the correct scales revealed by scale analysis. Numerical simulations conducted for several practical examples (e.g., extraction of an ionic species from a contaminated block) validate the predictions based on scale analysis, and confirm the correctness of both methods.
J. P.
Ollivier
Laboratory of Materials and Durability of Constructions, INSA-UPS, Department of Civil Engineering, National Institute of Applied Sciences, 135 Avenue de Rangueil, 31077 Toulouse, France
Sylvie
Lorente
Université de Toulouse; INSA; 135, avenue de Rangueil, F-31 077 Toulouse Cedex 04, France
307-320
Simulating Transport and Bioreduction of Cr(VI) by Employing the Dual-Enzyme Kinetic Model
Cr(VI) contamination of soil and groundwater is considered a major environmental concern. Bioreduction of Cr(VI) to Cr(III) can be considered an effective technology in remediating Cr(VI) contaminated sites. Among the Cr(VI) reducing bacteria, Shewanella oneidensis MR-1 (MR-1) is relatively effective. Reduction of Cr(VI) by MR-1 is defined by a nonlinear zeroth-order dual-enzyme kinetic model. Existing models are not designed to simulate transport and bioreduction of Cr(VI) by employing the dual-enzyme kinetic model. The objective of this paper is to present a finite element model capable of simulating transport and bioreduction of Cr(VI) by employing the dual-enzyme kinetic model. The model developed is accurate and can provide oscillation free results when Pn ≤ 50, PnCn ≤ 5, and Cn ≤ 1 for continuous sources, with Pn and Cn as the Peclet and Courant numbers, respectively. For pulse sources, accurate model predictions are obtained when, Pn ≤ 20, PnCn ≤ 5 and Cn ≤ 1. The accuracy of the model predictions is also a function of the degree of reliability and certainty with which its kinetic parameters are estimated.
Akram
Hossain
Civil and Environmental Engineering, Washington State University, Richland, WA 99354
321-334
Dependence of Elastic Properties of Materials on Their Porosity: Review of Models
The paper presents a review of models relating elastic moduli of porous materials with porosity. Dry isotropic porous materials with a homogeneous and continuous solid matrix are considered, excluding granular and fractured materials. The models are grouped into six classes, taking into account methodological differences adopted for their derivation. Quantitative predictions for most of the models are compared within specified groups and then a few representatives of the groups of models are analyzed for two different ranges of porosity. A short discussion of their applicability and limitations is included.
Mariusz
Kaczmarek
Institute of Environmental Mechanics and Applied Computer Science, Bydgoszcz University, Chodkiewicza 30, 85-064 Bydgoszcz, Poland
Marc
Goueygou
Institute of Electronics, Microelectronics and Nanotechnology (UMR CNRS 8520), Ecole Centrale de Lille, BP 48, 59651 Villeneuve d'Ascq Cedex, France
335-355
Unsteady Flow and Heat Transfer of a Viscous Fluid in the Stagnation Region of a Three-Dimensional Body Embedded in a Porous Medium
The unsteady flow and heat transfer flow of a viscous fluid in the stagnation region of a three-dimensional body embedded in the fluid-saturated porous medium was studied. The effects of the presence of the solid matrix and of viscous dissipation were analyzed. Both the nodal-point region and the saddle-point region were considered. With appropriate transformation, the boundary layer equations were reduced to semisimilar equations. Numerical solutions of these equations were obtained using the local nonsimilarity method with second-order truncation.
I. A.
Hassanien
Department of Mathematics, Faculty of Science, Assiut University, Assiut, Egypt
Fouad S.
Ibrahim
Department of Mathematics, Faculty of Science, Assiut University, Egypt
Gh. M.
Omer
Department of Mathematics, Faculty of Science, Assiut University, Assiut, Egypt
357-372
Experimental Investigation of Heat Transfer to a Metallic Rodin a Fluidized Bed of Small Particles
The effect of heat carriers on heat transfer to a cylindrical metal bar was investigated in a lab setup fluidized bed with small spherical solids (2.7 mm glass beads and steel balls). Rods of aluminum and steel, each with 10 and 20 mm diameter and 60 mm length, were heated by means of hot air. In each experiment, the temperature of the center of solid was measured at various intervals of time. The effect of various parameters such as air velocity, air temperature, mass ratio of fluidizing material to solid, type of fluidizing material, diameter of fluidizing material, and diameter of solid were investigated. The rate of heat transfer increases with decreasing immersed solid diameter, increasing the fluidizing material thermal conductivity, decreasing fluidizing medium size, and increasing air temperature, but air velocity and amount of fluidizing material must be optimized to convert the system to a well-fluidized system and maximize the rate of heat transfer.
Mohammad S.
Hatamipour
University of Isfahan, Chemical Engineering Department, Isfahan University, Isfahan
373-380
Experimental Apparatus and Mathematical Model for Determination of Parameters of Capillary Rise in Fabrics
In this study, an experimental device assuring the vertical suspension of a cloth surface and permitting the measure of the capillary ascension and the mass of liquid rising in fabrics is developed. The results show that the construction of the fabric and the composition and the number of yarns per centimeter have a significant influence on the diffusion coefficient, the height of the liquid at equilibrium, and the liquid mass absorbed by the fabric. The mathematical model proposed allows the determination of the governing diffusion coefficient.
Mohamed
HAMDAOUI
Laboratoire d'Etudes des SystÃ¨mes Thermiques et EnergÃ©tiques; and DÃ©partement de GÃ©nie Textile, Ecole Nationale d'IngÃ©nieurs de Monastir, (E.N.I.M), 5019 Monastir, Tunisie
Faten
Fayala
Laboratoire d'Etudes des Systèmes Thermiques et Energétiques; and Département de Génie Textile, Ecole Nationale d'Ingénieurs de Monastir, (E.N.I.M), 5019 Monastir, Tunisie
Sassi Ben
Nasrallah
Laboratoire d'Études des Systèmes Thermiques et Énergétiques, Ecole Nationale d'Ingénieurs
de Monastir, Monastir 5019 Tunisie
381-392