Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
10
8
2007
The Effect of Capillary Forces in a Porous Electrode on Output Current Voltage Characteristics of Fuel Cell with Polymer Proton Exchange Membrane
A mathematical isothermal model of a polymer proton exchange membrane fuel cell (PEMFC) cathode accounting for the capillary forces is derived and discussed. On the basis of analytical and numerical calculations, it is shown that capillary forces have a principal effect on the operating voltage drop due to a thin water film arising in wet-proofed pores under certain conditions and thus presenting the burden barrier for oxygen diffusion as compared with ordinary oxygen diffusion in a gas mixture. The calculations made are in good accordance with known experimental data.
V. E.
Nakoryakov
S. S. Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Vladimir G.
Gasenko
Institute for Advanced Studies, 630090 Novosibirsk, Russia
739-750
Elastic Waves at Porous/Porous Elastic Half-Spaces Saturated by Two Immiscible Fluids
Reflection and transmission phenomena of plane elastic waves at a plane interface between two different nondissipative porous elastic half-spaces saturated by two immiscible fluids are investigated. The theory of porous elastic media saturated by two immiscible fluids developed by Tuncay and Corapcioglu (1997) is employed. The boundary between the two half-spaces is assumed to be sealed so that the fluids are restricted inside the aggregate. Amplitude and energy ratios of various reflected and transmitted waves are found to be the functions of angle of incidence and elastic properties of the half-spaces. These amplitude and energy ratios are computed numerically for a specific model, and their variations are depicted graphically against the angle of incidence. Results of some earlier authors have been reduced as a particular case of the present formulation.
S. K.
Tomar
Department of Mathematics, Panjab University, Chandigarh 160 014, India
Ashish
Arora
Department of Mathematics, Guru Nanak Dev University, Amritsar 143 001, Punjab, India
751-768
Simulating Subsurface Temperature under Variable Recharge
A distributed numerical model utilizing MacCormack finite difference method is developed to simulate the transient subsurface temperature profiles under time varying groundwater recharge. It is not restricted to constant percolation rate and sinusoidal temperature variations as is the case in most models. The model is validated with the data available for the Nagaoka plain, Japan showing good agreement for the computed subsurface temperatures having correlation coefficient (as R2) and root mean square error (RMSE) as 0.89 and 0.42, respectively. The model is employed to investigate the alteration in the subsurface thermal regime due to variable recharge resulting from precipitation in South Korea. Results reveal that the subsurface thermal regime is influenced significantly by the temporal variability in groundwater recharge and temperature at the surface, and subsurface temperatures are not necessarily sinusoidal at all depths. Seasonal variations and the effect of short term hydrological phenomena are clearly depicted in simulated results. The temporal variations of the subsurface temperature are highly nonlinear near the ground surface and become almost linear beyond 10 m. The subsurface temperature profiles vary significantly from one cycle to other and tend to be vertical beyond 15 m. Its variability also depends upon the Peclet number.
Ashok K.
Keshari
Department of Civil Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
Min-Ho
Koo
Department of Geoenvironmental Sciences, Kongju National University, Kongju City, Chungnam 314-701, Korea
769-782
Soret Effect on Double-Diffusive Boundary Layer Flows in a Vertical Porous Cavity
A thorough analytical and computational investigation is performed to study the Soret effect on double-diffusive boundary layer flows in a vertical porous layer. The present investigation is focused on situations where the boundary layer scale power index (δ ∼ RmT) changes from m = −2/5 to m = −1/2, in which the Soret effect plays a central role. It is found that, depending on the Lewis number, there exist various domains in the N-SP plane where the boundary layer presents specific behaviors. In these domains, the horizontal profiles of velocity and fluid density are of boundary layer type, even though neither the temperature nor the concentration profiles exhibited a boundary layer character. For large values of Le, the thickness of the vertical boundary layer was found to increase or decrease with SP, depending on the sign of the buoyancy ratio, N. Some new correlations are derived for the boundary layer thickness scale, and the effect of the Soret coefficient is emphasized.
M.
Er-Raki
Faculty of Sciences Semlalia, Physics Department, B.P. 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
Abdelkhalk
Amahmid
Faculty of Sciences Semlalia, Physics Department, UFR TMF, BP 2390, Marrakesh, Morocco
Mahmoud
Mamou
National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
M.
Bourich
Faculty of Sciences Semlalia, Physics Department, UFR TMF, BP 2390, Marrakesh, Morocco
783-795
Influence of a Partial Slip on Flows of a Second Grade Fluid in a Porous Medium
In this article, exact analytical solutions for general periodic flows of a second grade fluid are obtained in the presence of partial slip and a porous medium. Three types of flow problems are considered. The exact solutions of the flow problems are obtained using Fourier transform treatment. Moreover, some flows generated by certain special oscillations are also included in each case. It is found that the velocity profile is of the wave nature and that amplitude of the wave decreases when the partial slip parameter increases.
Saleem
Ashgar
Department of Mathematical Sciences, COMSATS Institute of Information Technology, Islamabad, Pakistan
Chaudry Masood
Khalique
Department of Mathematical Sciences, International Institute for Symmetry Analysis and Mathematical Modelling, North West University, Mmabatho 2735, South Africa
R.
Ellahi
Department of Mathematics and Statistics, FBAS, IIUI, Islamabad, Pakistan; Department of Mathematics, Faculty of Science, Taibah University, Al-Madeenah, Saudi Arabia
797-805
The Influence of Hall Current on Rotating Flow of a Third Grade Fluid in a Porous Medium
This investigation is concerned with the effect of Hall current on the steady rotating flow of a third grade fluid in a porous medium. The hydromagnetic flow between the two stationary plates is induced by a constant applied pressure gradient. Modified Darcy's law has been used in the flow modeling. Homotopy analysis method (HAM) has been employed for the analytic solution of the arising nonlinear problem. The effects of various interesting parameters on the velocity components are seen through graphs and a discussion.
Muhammad
Sajid
Department of Mathematics and Statistics, International Islamic University, Islamabad 44000, Pakistan
807-820
Nonlinear Convection in a Sparsely Packed Porous Medium Due to Compositional and Thermal Buoyancy
Soret-driven convection in a two-component fluid layer subject to vertical temperature and concentration gradients is investigated analytically and numerically. The Darcy-Lapwood-Brinkman model for the momentum equation and the Boussinesq approximation is used to study the linear and weakly nonlinear properties of convection in two-component fluid in a sparsely packed porous medium due to compositional and thermal buoyancy. We have derived a nonlinear twodimensional Landau-Ginzburg equation with real coefficients near the onset of stationary convection at the supercritical pitchfork bifurcation. We have studied the Nusselt number contribution from Landau-Ginzburg equation at the onset of stationary convection. Two coupled nonlinear one-dimensional Landau-Ginzburg type equations with complex coefficients near the onset of oscillatory convection at the supercritical Hopf bifurcation are derived and the stability regions of travelling and standing waves are discussed.
S. G.
Tagare
Disha Institute of Management and Technology, Satya vihar, Vidhan Sabha-Chandrakhuri Marg 492101, Raipur, India
A. Benerji
Babu
Department of Mathematics, National Institute of Technology Warangal, Warangal 506004, A.P., India
823-839