Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
8
5
2005
Academician Vladimir Nakoryakov
Vladimir
Kuznetsov
Kutateladze Institute of Thermophysics of Siberian Branch of Russian Academy of Sciences
Robert I.
Nigmatulin
Department of Multiphase Systems Mechanics Thermophysics Institute, Siberian Branch of the USSR Academy of Sciences
429-430
Application of a Dewatering Model for Fibroporous Media under Constrained Uniaxial Compression
The governing equations of fluid flow through a deforming porous medium are considered for saturated and unsaturated flow. A uniaxial compression test cell is described. A strain-hardening formulation is presented based on nonlinear poroelasticity and "crushable-foam" plasticity models, which have been verified and applied in dewatering analysis of fibroporous media. Two- and three-dimensional models, including solid and liquid phases, are analyzed based on the isotropic poroelasticity, crushable-foam plasticity behavior, and contact theory. Definition and determination of material parameters are based on compression tests. A finite element analysis is implemented for a uniaxial compression test and is verified based on experiment data. A contact model is examined. Important mechanical quantities for solid and liquid phases, such as pore pressure, velocities, plasticity strain, deformation, and fluid behavior, are presented. A comparison of numerical solutions with experimental results shows good agreement.
Jeffrey G.
Lounghran
School of Engineering, James Cook University
Mei
Duan
School of Engineering, James Cook University, Townsville, Queensland 4811, Australia
431-442
Flow and Heat Transfer in an Inclined Channel Containing Fluid Layer Sandwiched between Two Porous Layers
The fully developed flow and heat transfer in an inclined channel consisting of a fluid layer sandwiched between two porous matrix layers is analyzed. The flow in the porous medium is modeled using the Brinkman equation. The viscous and Darcy dissipation terms are included in the energy equation. The transport properties of the fluids in all three regions are assumed to be constant. The continuity conditions for the velocity, temperature, shear stress, and heat flux at the interfaces between the porous and fluid layers are assumed. The governing equations, which are coupled and nonlinear, are solved using the regular perturbation method. The influence of the physical parameters governing the flow, such as the porous parameter, Grashof number, viscosity ratio, conductivity ratio, and inclination angle on velocity and temperature fields, are evaluated and depicted graphically.
M.S.
Malashetty
Gulbarga University
Jawali
Umavathi
Gulbarga University
J. Prathap
Kumar
Department of Mathematics, Gulbarga University, Gulbarga-585 106, Karnataka
443-453
Hydrodynamic Boundary Conditions Effects on Soret-Driven Thermosolutal Convection in a Shallow Porous Enclosure
A comparative study on fluid flow and heat and mass transfer, induced by Soret-driven thermosolutal convection in a horizontal porous layer subject to constant fluxes of heat, is conducted for the cases where both horizontal boundaries are stress-free or rigid. The problem formulation is based on the Brinkman-extended Darcy model with the Boussinesq approximation, and the governing equations are solved, analytically and numerically, using a finite-difference method. The critical Rayleigh number for the onset of supercritical and subcritical convection is predicted explicitly as a function of the governing parameters. The threshold for oscillatory flows is also predicted, and the stability diagram, defining various convective regimes, is illustrated. As expected, both free and rigid boundaries yield results that are identical to those predicted by the Darcy model when the Darcy number is small enough. For sufficiently large values of the separation parameter φ, the Nusselt and Sherwood numbers corresponding to free and rigid boundaries exhibit asymptotic behaviors. It is also found that, as expected, the flow intensity and heat and mass transfer rates are more affected by thermal diffusion effects in the case of free boundaries in comparison to rigid ones.
M.
Bourich
Faculty of Sciences Semlalia, Physics Department, UFR TMF, BP 2390, Marrakesh, Morocco
Mohammed
Hasnaoui
Cadi Ayyad University, Faculty of Sciences Semlalia, Physics Department, UFR TMF, Laboratory of Fluid Mechanics and Energetics (LMFE), B.P. 2390, Marrakech, Morocco
Mahmoud
Mamou
National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
Abdelkhalk
Amahmid
Faculty of Sciences Semlalia, Physics Department, UFR TMF, BP 2390, Marrakesh, Morocco
455-469
Liquid Flow Analysis in Concentric Annular Heat Pipes Wicks
In this paper, two models are developed to predict liquid pressure drop and velocity profile in the wicks of concentric annular heat pipes. A steady-state incompressible laminar flow is modeled in the wicks based on velocity and pressure mean values by the extended Darcy-Brinkman model. The corresponding one- and two-dimensional governing equations are solved analytically and numerically, respectively, in the range of low to moderate radial Reynolds numbers. It has been found that there is a difference, about 12% in the worse case, between the total pressure drops of the two models. Whereas, the predicted total pressure drop by the one-dimensional model and that of the Darcy model are in good agreement.
Ali
Nouri-Borujerdi
School of Mechanical Engineering, Sharif University of Technology, P. O.Box 11365-9567, Tehran, Iran; Dipartimento of Mechanical Engineering, Islamic Azad University, South Tehran Branch Tehran, Iran
Mohammad
Layeghi
Department of Wood & Paper Science & Technology, University of Tehran; and School of Mechanical Engineering, Sharif University of Technology, Iran
471-480
Combined Forced-Convective and Radiative Heat Transfer in Cylindrical Packed Beds with Constant Wall Temperatures
Hydrodynamically fully developed and thermally developing turbulent forced-convection in cylindrical packed beds heated at constant wall temperatures are numerically studied based on a zero-equation turbulence model accounting for the effect of thermal radiation. The macroscopic momentum equation considers the effects of turbulence and hydrodynamic dispersion in addition to Darcy-Brinkman-Forchheimer flow resistances, while the effects of thermal radiation, turbulence, and thermal dispersion are taken into account in the energy equation. The hydrodynamic dispersion term associated with spatial fluctuations of microscopic time-mean velocity in the momentum equation is modeled in a similar form to Boussinesq's eddy diffusivity model for Reynolds stress. The effective Prandtl numbers for dispersion and turbulence are assumed to be the same as each other and are adjusted so as to reproduce the experimental data of pressure gradient obtained by Fand and Thinakaran (ASME J. Fluids Eng., vol. 112, pp. 84−88, 1990). Radiation heat transfer in packed beds is analyzed based on the P1 approximation to the equation of transfer and the correlated-radiative properties of opaque packed spheres. It is shown that the coupled hydrodynamic dispersion and turbulence term in the momentum equation affects the pressure gradients in packed beds. Moreover, obtained theoretical results of velocity profiles, temperature profiles, and heat transfer characteristics are favorably compared to available experimental data.
San San
Yee
Department of Mechanical and Energy Systems Engineering, Oita University, Oita 870-1192, Japan
Kouichi
Kamiuto
Department of Mechanical and Energy Systems Engineering, Oita University, Oita 870-1192, Japan; Kyushu University, Fukuoka 812 Japan
481-492
Unsteady Combined Heat and Moisture Transfer in Unsaturated Porous Soils
Many works in the field of science and engineering, such as agronomy and building science, are physically related to soils and require an accurate determination of temperature and moisture content spatial distributions. In the building science area, for example, mathematical models are developed to provide better indoor thermal comfort with lower energy consumption and, mainly in low-rise buildings, the heat and moisture transfer through soils plays an important role on the energy and mass balances. Although, the presence of moisture can strongly affect the temperature distribution in soils due, especially, to the evaporation and/or condensation mechanisms and to the strong variation of their thermophysical properties, building simulation codes normally do not take into account the soil moisture effects for predicting the ground heat transfer. Therefore, in order to calculate the temperature profiles in a more accurate way, a computational code has been developed and conceived to model the coupled heat and moisture transfer in soils. The presented methodology is based on the theory of Philip and De Vries, using variable thermophysical properties for two types of soil with different chemical composition and porous size distribution. The governing equations were discretized using the finite-volume method, and a three-dimensional model was used for describing the physical phenomena of heat and mass transfer in unsaturated moist porous soils. The robust MultiTriDiagonal-Matrix Algorithm was used to solve this strongly-coupled problem, allowing one to use high time steps for long-term simulations. In conclusion, effects of boundary conditions for the soil, such as solar radiation, water table, and adiabatic and impermeable surfaces on the temperature and moisture content profiles, were presented. A sensitivity analysis of grid refinement and time step is presented as well. Additionally, daily average temperatures and moisture contents for different depths are also shown and compared for sandy silt and backfill soils.
Gerson Henrique
Dos Santos
Thermal Systems Laboratory, Department of Mechanical Engineering, Pontifical Catholic University of Parana, R. Imaculada Conceicao, 1155, Curitiba-PR, 80.215-901, Brazil
Nathan
Mendes
Thermal Systems Laboratory, Department of Mechanical Engineering, Pontifical Catholic University of Parana, R. Imaculada Conceicao, 1155, Curitiba-PR, 80.215-901, Brazil
493-510
Porous Medium Model for Investigating Transient Heat and Moisture Transport in Firefighter Protective Clothing under High-Intensity Thermal Exposure
The aim of this study is to understand the performance of firefighter protective clothing in preventing thermal injury of skin that may result from exposure to high-intensity thermal radiation. A mathematical model is developed to study transient heat and moisture transport through multilayer fabric assemblies. The model accounts for changes in thermophysical and transport properties of the fabric due to the presence of moisture. Numerical simulations are performed to study heat and moisture transport in wet fabrics that are subjected to intensive flash fire exposure. The numerical solutions are further analyzed to provide a detailed physical understanding of the transport processes. Moisture in the fabric tends to vaporize starting from the outside surface of the fabric to the inside surface of the fabric during heating, and then part of it recondenses in the interior of the fabric during the cooldown. It is observed that the temperature distribution in the fabric layers and the total heat flux to the skin are significantly influenced by the amount and distribution of the moisture in the protective clothing.
P.
Chitrphiromsri
Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7916, Raleigh, NC 27695-7910
511-528
Effect of Converging Boundaries on Flow Through Porous Media
An experimental investigation on the effect of converging boundaries on flow through porous media was carried out in a converging permeameter using crushed rock of size 4.73 mm as the media and water as fluid. The influence of converging boundaries on the resistance law relating the friction factor (fR) the and Reynolds number (RR) using the hydraulic radius as the characteristic length is examined. The present study aims to develop theoretical curves similar to the Moody diagram used in pipes, and to study the variation of fR and RR for different CR values taken as the third parameter for different ratios of the radii and for different radial lines. The relationships existing between the linear parameter a, the nonlinear parameter b, and the hydraulic radius R are also obtained theoretically and are verified with the experimental data.
Bhanu Prakasham
Reddy
Irrigation and CAD Department, Government of Andhrapradesh
529-539
Mixed Convection Heat and Mass Transfer with Thermal Radiation in a Non-Darcy Porous Medium
Similarity analysis is presented for simultaneous thermal radiation and mixed convection heat and mass transfer in thermal and solutal boundary layers over a semi-infinite vertical flat plate embedded in a fluid-saturated porous medium. The fluid is considered to be a gray, absorbing-emitting radiation but nonscattering and obeys Rosseland approximation for thermal radiation heat flux. It is observed that the radiation parameter R and temperature ratio CT enhance the heat transfer coefficient in the aiding flow, and their effect is more profound in the Darcy medium rather than in the non-Darcy medium. Even though the effect of radiation is to enhance the heat transfer rate in both aiding and opposing flows, it is more significant in the aiding flow. Unlike in the aiding-flow case, both in opposing-flow and in opposing-buoyancy cases, the effect of radiation is more pronounced in the non-Darcy medium. The effect of R and CT is to marginally increase the mass transfer coefficient. Even though radiation parameter does not have a direct impact on the mass transfer coefficient, it is worth mentioning that the mass transfer coefficient increases as a function of the Lewis number, more in the presence of radiation than in its absence.
G. P. Raja
Sekhar
Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur, 721302
M. K.
Partha
Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
541-549