Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
14
10
2011
IS THE POROUS MEDIUM APPROACH APPLICABLE TO PHENOMENA OF TRANSPORT IN BIOLOGICAL SYSTEMS?
Jacob
Bear
Department of Civil and Environmental Engineering, Technion−Israel Institute of Technology, Haifa, Israel and Kinneret College on the Sea of Galilee, Israel
847-848
INFLUENCE OF HEAT TRANSFER AND VARIABLE VISCOSITY IN VERTICAL POROUS ANNULUS WITH PERISTALSIS
In the present paper, we discuss the peristaltic flow of a Newtonian fluid in vertical porous annulus. The viscosity of the fluid is treated as a variable. The inner tube is at rest while the outer tube has a sinusoidal wave traveling down its motion. For the sake of simplicity, long wavelength and low Reynold number assumptions are taken into account. The perturbation solution for velocity field and temperature profile are presented in terms of σ2 (porosity parameter) and Gm (Grashof number). Numerical results that show the physical effects and the pertinent features are investigated at the end of the paper.
Sohail
Nadeem
Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000, Pakistan
Noreen Sher
Akbar
National University of Sciences and Technology, College of E & ME, Islamabad, Pakistan
849-863
COMBINED RADIATION AND NATURAL CONVECTION WITHIN AN OPEN-ENDED POROUS CHANNEL−VALIDITY OF THE ROSSELAND APPROXIMATION
The present article deals with a numerical study of coupled fluid flow and heat transfer by transient natural convection and thermal radiation in a vertical channel opened at both ends and filled with a fluid-saturated porous medium. The bounding walls of the channel are isothermal and gray. In the present study we assume the validity of the Darcy flow model and the local thermal equilibrium assumption. In order to examine the validity of the Rosseland approximation, the radiative term in the energy conservation equation was expressed via two different approaches. The first is based on the resolution of the radiative transfer equation (RTE) in the most general case while the second is based on assuming the Rosseland approximation to be valid. Numerical results show that the Rosseland approximation is valid only for optically thick media: τD ≥ 100 and far from the bounding walls. A parametric study shows that this approximation can be used with high confidence for large Planck number values: N ≥ 5,for temperature ratios close to 1 and/or for single scattering albedo near or equal to 1.
Abdesslem
Jbara
The National School of Engineers, University of Monastir, Ibn Aljazzar Street, 5019, Monastir, Tunisia
Khalifa
Slimi
ISTLS
Abdallah
Mhimid
Laboratoire d'Etudes des Systèmes Thermiques et Energétiques, Université de Monastir, Ecole Nationale d'Ingénieurs de Monastir, Rue Ibn Eljazzar, 5019 Monastir, Tunisia
865-882
ADEQUACY OF FINITE ELEMENT MODELS TO SIMULATE ADVECTIVE-DISPERSIVE TRANSPORT COUPLED WITH INTRA-PARTICLE DIFFUSION
Advective-dispersive transport coupled with intra-particle diffusion is encountered in both engineered and natural systems. Finite difference models (FDMs) and models based on the method of orthogonal collocation (MOC) are generally employed to simulate such transport. The FDM and the MOC, however, may have oscillatory results. The objective of this paper is to explore the relative accuracy of finite element models (FEMs) to simulate the advective-dispersive transport coupled with intra-particle diffusion for a range of adsorbents. Four FEMs that employ linear basis functions for the solution were considered. The FEMs explored are the Galerkin FEM (GFEM), the Petrov-Galerkin FEM (PGFEM), the Crank-Nicolson-Galerkin FEM (CNGFEM), and the Crank-Nicolson-Petrov-Galerkin FEM (CNPGFEM). The model predictions were compared with experimental data obtained from the literature. The model predictions were generally found to be in good agreement with the experimental data. The models were, in general, stable. It was found that the predictions by the different models were virtually the same. The CNGFEM, however, can be considered preferable over the other models for its ability to provide results of higher-order temporal accuracy.
Md. Akram
Hossain
Civil and Environmental Engineering, Washington State University, Richland, Washington 99354
883-892
STEADY MIXED CONVECTION FLOW IN A LID-DRIVEN SQUARE ENCLOSURE FILLED WITH A NON-DARCY FLUID-SATURATED POROUS MEDIUM WITH INTERNAL HEAT GENERATION
Steady state two-dimensional mixed convection flow in a square cavity filled with a non-Darcy fluid-saturated porous medium with internal heat generation is investigated numerically. The two vertical surfaces of the square enclosure are adiabatic and the horizontal surfaces are kept at constant temperature where the top surface is moving with constant velocity. The Navier-Stokes equations and the energy equation governing the mixed convection flow are nondimensionalized and then solved by using the penalty finite element method with bi-quadratic square elements. The flow and heat transfer are strongly influenced by the Richardson number. The porous medium within the cavity is not a real force but expressed via friction which induces a force opposite to the flow direction that resists the motion. This results in a reduction in the thermal currents of the flows.
Mahesh
Kumari
Department of Mathematics, Indian Institute of Science, Bangalore 560 012, India
Girishwar
Nath
Professor S. K. Sinha, KNIT Campus, IV/17, KNIT, Sultanpur 228118, India
893-905
DEVELOPMENT OF PREMIXED BURNER BASED ON STABILIZED COMBUSTION WITHIN DISCRETE POROUS MEDIUM
Though extensive research has been carried out on porous media combustion (PMC), more attention is needed to explore the feasibility of this promising technology for practical applications. In the present study an attempt is made to develop an eco-friendly and compact, premixed liquified petroleum gas (LPG) burner based on matrix-stabilized combustion in porous medium (PM). The premixing mechanism is the combination of a swirler and steel wire-mesh packing. The preheating zone is made up of ceramic (porcelain) foam and the reaction zone is a packed bed of solid (Al2O3) spheres. The experiments are conducted with different layers and sizes (10, 20, and 30 mm) of alumina balls. Transient and steady temperature distributions and emissions (NO, CO, and SO2) are measured in each case for a constant equivalence ratio. It is found that the combination of porcelain foam (preheat layer) and one reaction layer made of 30-mm-size balls gives the best performance. It is observed that the proposed burner (PMB) can yield a 60% saving in fuel and 76% NOx reduction, compared to the conventional burner (CB). The CO and SO2 emissions are also well within the global standards. The thermal efficiencies of the PMB and CB are also estimated by proper experiments. For a fuel input of 0.4 Lpm (liters per minute) the thermal efficiency of the PMB is found to be 56% whereas for the CB, it is 46% at a fuel input of 0.5 Lpm.
M. Abdul
Mujeebu
School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia
M. Z.
Abdullah
Porous Media Combustion Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia
M. Z.
Abu Bakar
School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia
Abdulmajeed A.
Mohamad
Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, CEERE, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
909-917
ON THE EFFECTIVE THERMAL CONDUCTIVITY OF POROUS PACKED BEDS WITH UNIFORM SPHERICAL PARTICLES
Point contact models for the effective thermal conductivity of porous media with uniform spherical particles have been briefly reviewed. The model of Zehner and Schlunder (1970) has been further validated with recent experimental data over a broad range of conductivity ratios from 8 to 1200 and over a range of solids fractions up to ~0.8. The comparisons further confirm the validity of the Zehner-Schlunder model, known to be applicable for conductivity ratios less than ~2000, above which area contact between the particles becomes significant. This validation of the Zehner-Schlunder model has implications for its use in the prediction of the effective thermal conductivity of water frost (with ice-to-air conductivity ratio ~100) which arises in many important areas of technology.
Max
Kandula
ASRC Aerospace, John F. Kennedy Space Center, FL, USA
919-926
SERIES SOLUTION FOR THE RADIATION-CONDUCTION INTERACTION ON UNSTEADY MHD FLOW
Series solutions for momentum and heat transfer in the boundary layer of a viscous fluid over a stretching surface are constructed by a homotopy analysis method (HAM). The magnetohydrodynamic (MHD) fluid saturates the porous medium. Analytic treatment for the arising problem is made for velocity components and temperature. Graphical results of velocity components, local skin friction coefficients, and local Nusselt number are presented for various values of pertinent dimensionless parameters.
I.
Ahmad
Department of Mathematics, Azad Kashmir University, Muzaffarabad 13100, Pakistan
T.
Javed
Department of Mathematics, Quaid-i-Azam University; International Islamic University, 45320 Islamabad
Tasawar
Hayat
Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan; Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science,
King Abdulaziz University, Jeddah 21589, Saudi Arabia
Muhammad
Sajid
Department of Mathematics and Statistics, International Islamic University, Islamabad 44000, Pakistan
927-941
CONDITION FOR NEGLECTING UPSTREAM CONDITIONS WHEN SIMULATING FLOW IN GRANULAR BEDS
One of the most frequent assumptions concerning fluid flow into porous tanks consists in neglecting the influence of upstream conditions on the flow inside the porous bed. The present study establishes the conditions when this assumption is valid. We determine the longitudinal distance into the porous bed after which the flow becomes uniform regardless of the velocity field upstream of the porous bed. We evaluate this distance of homogenization as a function of different parameters: tank fluid inlet velocity, entrance length of the tank, and Reynolds and Darcy numbers.
Mouaouia
Firdaouss
LIMSI-CNRS (UPR 3251), BP 133, 91405 Orsay Cedex, France, and UFR 923, Universite Pierre et Marie Curie, Paris 6, France
M.
Pons
LIMSI-CNRS (UPR 3251), BP 133, 91403 Orsay Cedex, France
943-949