Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
17
2
2014
SORET AND DUFOUR EFFECTS ON MIXED CONVECTION FLOW OF COUPLE STRESS FLUID IN A NON-DARCY POROUS MEDIUM WITH HEAT AND MASS FLUXES
An analysis is presented to investigate the Soret and Dufour effects on mixed convection heat and mass transfer along a semi-infinite vertical plate embedded in a non-Darcy porous medium saturated with couple stress fluid with flux distributions. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations and then solved numerically. Profiles of dimensionless velocity, temperature, and concentration are shown graphically for various values of Dufour number, Soret number, and couple stress parameter. Nusselt number and Sherwood numbers are calculated and presented in table form.
D.
Srinivasacharya
Department of Mathematics, National Institute of Technology, Warangal-506004,
India
Kolla
Kaladhar
Department of Mathematics, National Institute of Technology Puducherry, Karaikal 609605, India
93-101
PORE SCALE SIMULATION VS VOLUME AVERAGED TREATMENT OF TURBULENT REACTING AND NONREACTING FLOWS IN A POROUS MEDIUM
Reacting and nonreacting flows in porous media have been studied in the present paper via two approaches, pore scale simulation and volume averaging model. The accurateness of the volume averaging model has been examined through pore scale simulation of turbulent flow in a simple but often used porous medium consisting of a staggered arrangement of square cylinders. The results show that, although the variations of temperature and turbulent characteristics are significant over a pore, the turbulent kinetic energy, flame speed, and temperature are fairly well predicted by the volume averaging model. However, the volume averaging model is unable to predict the flame curvature and the pore level local high temperature regions of the gas phase in the turbulent reacting flow in porous media which can be up to 18%. Other shortcomings of the volume averaging model are also disclosed through the sensitivity analysis of volume averaging solution to the volumetric heat transfer and extinction coefficients of porous media.
Nima F.
Jouybari
Division of Fluid Mechanics, Lulea University of Technology, 971 87 Lulea, Sweden; Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran
Mehdi
Maerefat
Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran
Majid E.
Nimvari
Faculty of Engineering Technologies, Amol University of Special Modern Technologies, Amol, Iran
103-116
EFFECT OF g-JITTER ON THE ONSET OF DOUBLE-DIFFUSIVE CONVECTION IN FLUID/POROUS LAYER
Linear stability analysis of double-diffusive convection in a binary fluid layer/saturated porous layer is performed. The prime objective of this study is to investigate the influence of time-periodic vertical vibrations on the onset threshold. The regular perturbation method is used to compute critical Rayleigh number. The first nontrivial correction to the critical Rayleigh number is calculated as a function of frequency of modulation, solute Rayleigh number, Lewis number, Prandtl number, Darcy number, normalized porosity, and viscosity ratio. In the degenerate cases of Brinkman model the results of Darcy porous layer and viscous fluid layer are recovered, respectively, for very small and large Darcy number. In general, gravity modulation exhibits a stabilizing effect Effective control of convection is achieved by proper tuning of governing parameters. The results of this study are useful in the areas of crystal growth in microgravity conditions and also in bridging the gap between the results of Darcy and viscous fluid layer limits.
Mahantesh S.
Swamy
Department of Mathematics, Government College, Gulbarga 585 105, India
117-128
NUMERICAL STUDY ON TURBULENCE EFFECTS IN POROUS BURNERS
This paper presents numerical simulation of combustion of air/methane mixture in a cylindrical porous burner while the turbulence between the pores of porous medium has been considered via an explicit model. Results of both laminar and turbulence models are presented and compared for different equivalence ratios and several pore diameters. The turbulent kinetic energy increases along the burner due to the turbulence created by the solid matrix with a sudden jump at the flame front due to the thermal expansion. Also, because of the higher diffusion due to the turbulence, the reactants become more preheated, leading to an increase in the burning speed in comparison to the laminar results. Higher burning speed in turbulence cases decreases the flame temperature and shifts the maximum temperature location toward downstream of the burner. It is found that at higher equivalence ratios, the effects of turbulence become more significant. Taking into account the turbulence effects results in burning speeds which are in good agreement with the experimental data. Although the increase of pore diameter in the laminar model decreases the burning speed due to lower volumetric heat transfer between the phases, higher effective diffusion results in higher burning speed in the turbulence model.
Majid E.
Nimvari
Faculty of Engineering Technologies, Amol University of Special Modern Technologies, Amol, Iran
Mehdi
Maerefat
Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran
M. K.
El-Hossaini
Energy Research Centre, Research Institute of Petroleum Industry, P.O. Box 14665-137, Tehran, Iran
Nima F.
Jouybari
Division of Fluid Mechanics, Lulea University of Technology, 971 87 Lulea, Sweden; Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran
129-142
EFFECTS OF MAGNETOHYDRODYNAMICS ON PERISTALTIC FLOW OF JEFFREY FLUID IN A RECTANGULAR DUCT THROUGH A POROUS MEDIUM
This paper presents a theoretical study on the effects of magnetohydrodynamics on the peristaltic flow of Jeffrey fluid in a rectangular duct under the constraints of low Reynold number and long wavelength. Porous media is also taken into account. The governing equations are modeled and then solved analytically. Numerical integration is used to analyze the novel features of volumetric flow rate, average volume flow rate, instantaneous flux, and the pressure gradient. The trapping phenomenon for different physical parameters has been presented through stream lines. The role of pertinent parameters is illustrated through graphs and tables. Comparison with the existing literature is also made.
R.
Ellahi
Department of Mathematics and Statistics, FBAS, IIUI, Islamabad, Pakistan; Department of Mathematics, Faculty of Science, Taibah University, Al-Madeenah, Saudi Arabia
M. Mubashir
Bhatti
Department of Mathematics and Statistics, FBAS, IIUI, Islamabad, Pakistan
Arshad
Riaz
Department of Mathematics and Statistics, FBAS, IIUI, Islamabad, Pakistan
Mohsen
Sheikholeslami
Faculty of Mechanical Engineering, Babol University of Technology, Babol, Islamic Republic of Iran
143-157
THE DECLINING AFFINITY OF MICROPOROUS HYDROTALCITE-SILICA MEMBRANE FOR CARBON DIOXIDE
Single permeation test reveals that excessively high sintering temperature caused unnecessary bloating and collapse of micropores to form meso- and macropore structures. It also caused reduction in carbon dioxide adsorption capacity as a result of diminishing affinitive hydrotalcite phase in the pore structures. The carbon dioxide permeance was higher than that of hydrogen, indicating affinity had greater effect than the diffusivity and molecular sieving. This is also evident from the direction of the carbon dioxide permeance that decreased with increasing sintering temperatures, confirming the dominating surface adsorption mechanism over the ordinary gas diffusion in the membrane within the operating boundaries.
Ahmed Daham
Wiheeb
School of Chemical Engineering, Universiti Sains Malaysia 14300 Nibong Tebal, Penang, Malaysia; Department of Chemical Engineering, College of Engineering, University of Tikrit, Salah ad Din, Iraq
Mohd Azmier
Ahmad
School of Chemical Engineering, Universiti Sains Malaysia 14300 Nibong Tebal, Penang, Malaysia
Muhamad Nazri
Murat
School of Chemical Engineering, Universiti Sains Malaysia 14300 Nibong Tebal, Penang, Malaysia
J.
Kim
Department of Chemical Engineering, Kyung Hee University, Global campus, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea
Mohd Roslee
Othman
School of Chemical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia; Department of Chemical Engineering, Kyung Hee University, Global Campus, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, Republic of Korea
159-167
NUMERICAL INVESTIGATIONS OF STABILITY OF STRATIFIED VISCOELASTIC WALTERS' (MODEL B') FLUID/PLASMA IN THE PRESENCE OF QUANTUM PHYSICS SATURATING A POROUS MEDIUM
Quantum effects on the Rayleigh−Taylor instability in an inhomogeneous stratified incompressible, viscoelastic Walters' (model B') fluid/plasma through a porous medium are investigated. The linear growth rate is derived for the case where a plasma with exponential density, viscosity, viscoelasticity, and quantum parameter distribution is confined between two rigid planes at z = 0, z = h. The solution of the linearized equations of the system together with the boundary conditions leads to derive the dispersion relation (the relation between the normalized growth rate and square normalized behavior wave number) using the normal mode technique to explain the roles that the variables of the problem play. The behavior of growth rates with respect to the quantum effect and kinematic viscoelasticity are examined in the presence of porous medium, the medium permeability, and kinematic viscosity. The results show that the quantum effects bring about more stability for a certain wave number band on the growth rate of unstable configuration.
Veena
Sharma
Department of Mathematics & Statistics, Himachal Pradesh University Shimla-171 005, India
Radhe
Shyam
Department of Mathematics & Statistics, Himachal Pradesh University Shimla-171 005, India
Sudrshna
Sharma
Department of Mathematics & Statistics, Himachal Pradesh University Shimla-171 005, India
169-176
PROGRESSION OF A THERMAL FRONT IN POROUS MEDIA OF FINITE LENGTH DUE TO THE INJECTION OF AN INERT GAS
Thermal conduction and convection, associated with the flow of a gas through porous media are of importance for applications, e.g., heat trapping, thermal protection, and enhanced oil recovery. The analytical model generally considers a boundary at an infinite distance from the inlet. This article tracks the progression of the thermal front when the boundary is within a finite distance from the inlet. The system of equations was solved using numerical methods for a step change in temperature at the inlet. The dimensionless numbers representing the effects of conduction and convection, the heat capacities of the solid and the flowing phases, and the void fractions were introduced. The importance of the operating parameters on the progression of the thermal front and its dispersion were studied using these dimensionless numbers. For the values of the parameters considered in this article, the temperature at the center of the packed bed reached half the step size at the inlet after injection of about 300 pore volumes of inert gas. A similar system of equations was also solved analytically in this article for comparison with the simulated temperature profile. The extent to which the model can be used in analyzing the progression of the thermal front in a porous medium of finite length is discussed.
Bidhan C.
Ruidas
Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, India
Somenath
Ganguly
Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, West-Bengal, India
179-184