Begell House Inc.
Journal of Porous Media
JPM
1091-028X
20
1
2017
HEAT AND MASS TRANSFER CHARACTERISTICS OF Al2O3−WATER AND Ag−WATER NANOFLUID THROUGH POROUS MEDIA OVER A VERTICAL CONE WITH HEAT GENERATION/ABSORPTION
1-17
10.1615/JPorMedia.v20.i1.10
P. Sudarsana
Reddy
Department of Mathematics, RGM College of Engineering and Technology, Nandyal 518501, AP, India
Ali J.
Chamkha
Faculty of Engineering, Kuwait College of Science and Technology, Doha District, Kuwait;
Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200,
Jeddah 21589, Saudi Arabia; Mechanical Engineering Department, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Saudi Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, P.O. Box
10021, Ras Al Khaimah, United Arab Emirates
heat and mass transfer
Al2O3-water and Ag-water nanofluid
MHD
thermal radiation
chemical reaction
finite element method
In this article, we have presented a numerical solution to the MHD heat and mass transfer flow of a nanofluid through porous media over a vertical cone with heat generation/absorption, thermal radiation, and chemical reaction. Though we have different varieties of nanofluids, we have considered Al2O3−water and Ag−water based nanofluids (with volume fraction 1% and 4%) in this problem. The transformed conservation equations for the nanofluid are solved numerically subject to the boundary conditions using an efficient, extensively validated, variational finite element analysis. The numerical code is validated with previous studies. The influence of important nondimensional parameters, namely, nanoparticle volume fraction (φ), Prandtl number (Pr), magnetic parameter (M), mixed convection (Ra), buoyancy ratio (Nr), and space-dependent (A), temperature-dependent (B), thermal radiation (R), and chemical reaction (Cr) on velocity, temperature, and nanoparticle concentration fields as well as the skin-friction coefficient, Nusselt number, and Sherwood number are examined in detail and the results are shown graphically and in tabular form to illustrate the physical importance of the problem.
NUMERICAL SIMULATION OF HEAT AND MASS TRANSFER IN HUMIDIFIERS AND COOLING TOWERS
19-27
10.1615/JPorMedia.v20.i1.20
Leila
Zili-Ghedira
Energy and Thermal Systems Laboratory, National Engineering School of Monastir, University of Monastir, Avenue Ibn El Jazzar, 5019 Monastir, Tunisia
Hana
Gouider
Energy and Thermal Systems Laboratory, National Engineering School of Monastir, University of Monastir, Avenue Ibn El Jazzar, 5019 Monastir, Tunisia
Sassi Ben
Nasrallah
Laboratoire d'Études des Systèmes Thermiques et Énergétiques, Ecole Nationale d'Ingénieurs
de Monastir, Monastir 5019 Tunisie
humidifier
cooling tower
structure packing
porous media
numerical simulation
This paper deals with humidifiers and cooling towers and especially those involving structure packing. It is based on a model deduced from Whitaker's theory the humidifier or cooling tower is considered as a three-phase porous medium; solid, liquid, and gas. A numerical tool was elaborated on the basis of Whitaker's model. It allows predicting heat and mass transfer in humidifiers. The effects of the thermophysical properties of humidifier packing materials, the water−air exchange surface, and humidifier aspect ratio were examined.
NUMERICAL REPRESENTATIVE ELEMENTARY VOLUME GENERATION OF A SIMPLIFIED CEMENT PASTE AND ESTIMATION OF ITS DIFFUSIVITY AND COMPARISON WITH DEDICATED EXPERIMENTS
29-46
10.1615/JPorMedia.v20.i1.30
Nicolas
Seigneur
Universite libre de Bruxelles (ULB), Belgium
E.
L'Hopital
Institut de Radioprotection et Surete Nucleaire (IRSN), France
A.
Dauzeres
Institut de Radioprotection et Surete Nucleaire (IRSN), France
M.
Voutilainen
Department of Chemistry, University of Helsinki
V.
Detilleux
Bel V, Belgium
P.E.
Labeau
Universite libre de Bruxelles (ULB), Belgium
A.
Dubus
Universite libre de Bruxelles (ULB), Belgium
microstructure
diffusion
cement paste
random porous materials
numerical modelling
representative elementary volume
C-S-H
random walk
Archie's law
Cementitious materials are widely used in the concepts of radioactive waste disposal facilities. During the lifetime of these disposals, those materials will undergo physicochemical degradations. To assess their impacts, reactive transport modelling is used. Reactive transport codes modify the transport properties based on the modelled porosity evolution by using Archie's law as a feedback between porosity and diffusive properties. These laws are not suited to cementitious materials, whose pore structure is complex and expands over a wide range of pore sizes. The ultimate goal of this research is about developing a microstructure-based feedback relation for the diffusive properties of complex porous structures such as cementitious ones. Therefore, we developed an algorithm designed to generate numerical microstructures representative of simplified cement pastes and performed an experimental campaign consisting of dedicated experiments. A random-walk algorithm is used to compute the effective diffusion coefficients of our numerical microstructures. This paper investigates the description of the initial numerical microstructure and how transport properties are sensitive to different microstructural features that can be controlled from the designed algorithm. Simulations both on the experimental microtomograph and the generated microstructures allow to show that our models are complete to describe the microstructure and diffusion transport property of simplified cementitious materials. Sensitivity analysis is also provided, whose results show that a simple feedback relation cannot properly describe these transport properties. This gives confidence in our approach and its future extension toward the description of cementitious material degradations.
THREE-DIMENSIONAL NUMERICAL SIMULATION AND EXPERIMENTAL STUDIES OF PURE ALUMINUM AND ALUMINUM ALLOYS DURING GASAR PROCESS
47-65
10.1615/JPorMedia.v20.i1.40
Olga
Komissarchuk
School of Materials Science and Engineering, Dalian University of Technology, Lingong Road 2#, High Technology Zone, Dalian City, Liaoning, 116024, P.R. China
Mouhamadou A.
Diop
School of Aerospace, Department of Mechanics Engineering, Tsinghua University, China; NSERC/Alcoa Industrial Research Chair MACE3 Aluminum Research Center-REGAL, Laval University, Quebec G1V 0A6, Canada; Department of Physics, Universite Pierre et Marie Curie, 4 Place Jussieu, 75004, Paris-France
Hai
Hao
School of Materials Science and Engineering, Dalian University of Technology, Lingong Road 2#, High Technology Zone, Dalian City, Liaoning, 116024, P.R. China
Xinglu
Zhang
School of Materials Science and Engineering, Dalian University of Technology, Lingong Road 2#, High Technology Zone, Dalian City, Liaoning, 116024, P.R. China
Vladimir
Karpov
Department of Materials Science and Metal Processing, National Metallurgical Academy of Ukraine, Ukraine
Mario
Fafard
NSERC/Alcoa Industrial Research Chair MACE3 Aluminum Research Center-REGAL, Laval University, Quebec G1V 0A6, Canada
GASAR
porosity
lattice Boltzmann method
aluminum alloys
The process of melting metals in a hydrogen atmosphere and then casting into a mold, to ensure directional solidification, could result in the formation of pores within the metal−hydrogen usually grows as quasi-cylindrical pore normal to the solidification front as it is driven out of the solution. In this study, experimental and numerical analyses were performed on aluminum melt to investigate the formation of pores in the molten metal during the "GASAR" (Ukrainian acronym for gas-reinforced composite metals) fabrication process. The experimental aspect of this work was carried out on pure aluminum, and aluminum-based magnesium alloys at varying pressure and superheats processing conditions. A numerical lattice Boltzmann approach was adopted in modeling the melting-solidification process, homogeneous pore nucleation, and growth in the gas-solid material. The developed model was used to identify processing conditions in which hydrogen gas bubbles are stable in the molten metal before eutectic gas transformations in metal-hydrogen systems cause the metal to solidify. The usefulness of our numerical simulations in supporting experimental procedures aimed at understanding the complex physics phenomena inherent in the formation of ordered pore structures is demonstrated. Conditions for producing such porous material and their physics are also highlighted in this paper.
DETERMINATION OF CONVECTION-DISPERSION- MASS TRANSFER PARAMETERS IN POROUS MEDIA FLOWS USING COMPUTED TOMOGRAPHY
67-84
10.1615/JPorMedia.v20.i1.50
J. A.
Vidal Vargas
Faculty of Mechanical Engineering, Department of Petroleum Engineering, University of
Campinas, Cidade Universitaria Zeferino Vaz - Barão Geraldo, Campinas - São Paulo, Brazil,
13083-860
O. V.
Trevisan
Department of Petroleum Engineering, School of Mechanical Engineering, University of Campinas, Mendeleyev Street 200, Cidade Universitaria Zeferino Vaz − Barao Geraldo, Campinas − Sao Paulo, Brazil, 13083-860
dispersion coefficient
X-ray images
simulated annealing
carbonate rock
mass transfer coefficient
This paper focuses on the development and evaluation of a mathematical model for 1D miscible displacement across intrinsically heterogeneous porous media. The model, referred to as the total concentration model, is developed based on the convection-dispersion equation considering the interaction between the rock and the fluids. The model is suitable for treating the data obtained from CT scanners where the dopant deposits at the rock surface. Further, this paper presents a methodology to treat and use the vast amount of data rendered by CT scanners. The methodology involves a multiparametric fitting of the model to the lab data through the simulated annealing metaheuristic. As an application, conducted displacement tests are reported for two brines on a carbonate rock. Results show a very good fitting of the model to the experimental data. The procedure allowed determination of the dispersion coefficient, the mass transfer coefficient, the effective porosity of the porous medium, which differs from the medium porosity, and the amount of solute that is deposited on or removed from the porous medium.
A NUMERICAL STUDY ON MIXED CONVECTION OF NON-NEWTONIAN FLUID FLOW IN POROUS CHANNEL WITH AIDING AND OPPOSING NATURAL CONVECTION EFFECTS
85-98
10.1615/JPorMedia.v20.i1.60
Sima Baheri
Islami
Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran
Mir Aydin Khoddam
Tabrizi
Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran
Reza
Gharraei
Department of Engineering, Azarbayjan Shahid Madani University, Tabriz, Iran
mixed convection
porous medium
non-Newtonian fluid
modified Brinkmane-Forchheimer-extended Darcy model
In this study, a numerical investigation was performed on mixed convection of non-Newtonian fluid flow in a constant wall temperature porous channel. The power law and modified Brinkmane-Forchheimer extended Darcy models were used in non-Newtonian fluid and porous media simulations, respectively. The flow was laminar, steady, and incompressible. The governing equations were solved using the projection finite difference method by writing a FORTRAN program. The effect of power law index, Richardson number, and Darcy number on the fluid flow and heat transfer was investigated. The investigation on the influence of channel inclination when natural convection has aiding or opposing effect on forced convection is the novelty of this study. The results indicated that for opposing flow, forced convection effect was weakened by natural convection and centerline velocity increased, while for aiding flow it decreased. By decreasing the Darcy number to small values, the effect of the Richardson number on the hydrodynamic behavior along the channel became negligible. Nusselt number values were higher for shear thinning fluids than for shear thickening fluids. The velocity profiles in inclined channels were tended toward the bottom wall. Also, the variation of Nusselt number with channel inclination was more considerable for higher Darcy numbers.