Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
9
5
2006
Thermally Developing Forced Convection in a Bidisperse Porous Medium
The classical Graetz methodology is applied to investigate the thermal development of forced convection in a parallel-plate channel filled by a saturated bidispersed porous medium, with walls held at constant temperature. A two-velocity two-temperature model is employed for the porous medium. The analysis leads to an expression for the local Nusselt number as a function of the dimensionless longitudinal coordinate and parameters characterizing the porous medium (macropore volume fraction, interphase heat transfer parameter, thermal conductivity ratio, and effective permeability ratio).
Andrey V
Kuznetsov
Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695-7910, USA
D A
Nield
393-402
Hydrodynamic and Thermal Behavior of Gas Flow in Microchannels Filled with Porous Media
Laminar forced convection slip flow in parallel-plate microchannels filled with porous media is studied numerically. The governing momentum and energy equations are solved using the finite difference technique. The study is focused on the slip flow regime (i.e., for Knudsen numbers in the range 10−3 < Kn < 10−1 ) and the Darcy-Brinkman-Forchheimer model is used to model the flow inside the porous domain. The current study demonstrates the effects of Knudsen number Kn, Darcy number Da, Forchheimer number (Γ), and modified Reynolds number (Re ) on velocity slip and temperature jump at the wall(s). Results are given in terms of the product of the skin friction coefficient and the Reynolds number Cf Re* and the Nusselt number Nu. It is found that the skin friction is increased by: (i) increasing Darcy number and (ii) decreasing Knudsen number and/or Forchheimer number. Heat transfer is found to: (i) increase as the modified Reynolds number and/or Darcy number increases and (ii) decrease as the Knudsen number and/or Forchheimer number increases.
O. M.
Haddad
Department of Mechanical Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan
Moh'd Ahmad
Al-Nimr
Jordan University of Science and Technology
Yazan
Taamneh
Department of Aeronautical Engineering, Jordan Univesity of Science and Technology, Irbid,
Jordan
403-414
Effect of Convergent Angle on Nonlinear Flow through Porous Media
An experimental investigation on the effect of the convergent angle on nonlinear flow through porous media was studied in a converging permeameter. The scope of the present paper is to present the results of applying dimensional analysis to obtain a relationship between the friction factor and Reynolds number for flow in porous media with converging boundaries, using the volume diameter as the characteristic length, and also to develop an expression for a linear parameter and nonlinear parameter in terms of the volume diameter by the method of dimensional analysis. Using the friction factor and Reynolds number relationship, theoretical curves, which are similar to the Moody diagram used for pipe flow, are developed and verified with the help of existing experimental data. From the set of theoretical curves so obtained, the Reynolds number at which the friction factor and Reynolds number relationship deviates from Darcy's law and the Reynolds number at which turbulent flow is fully established are identified. In the present case, existing data of size 1.66 cm was used as media and water as fluid, to study the variation of the friction factor and Reynolds number with different ratios of the radii and for different convergent angles of a permeameter.
BHANU PRAKASHAM REDDY
N
ASSISTANT EXECUTIVE ENGINEER, FORMERLY PROFESSOR OF CIVIL ENGINEERING,NBKRIST,VIDYANAGAR
415-428
Forecasting Aquifer Parameters Using Artificial Neural Networks
This study proposes an artificial neural network (ANN) model to solve an inverse parameter identification problem for groundwater modeling. It is a problem for which the transmissivities can be obtained for given hydraulic heads. ANN may be a useful tool for parameter estimation problems because of its ability to model complex nonlinear relationships between state variables and system parameters without a priori assumptions of the nature of a relationship like a black box. To carry out a parameter estimation using the ANN, a hypothetical example has been examined under two scenarios, one involving the sink and/or source terms, the second without these. In the ANN model, the network is trained for about 5, 10, and 20% of all data, and then transmissivities in the other cells are forecasted. Results show that observed and forecasted transmissivities are in good agreement when about 10 and 20% of the hydraulic heads in the solution domain are known.
Halil
KARAHAN
Pamukkale University
M. Tamer
Ayvaz
Pamukkale University, Faculty of Engineering, Department of Civil Engineering, 20017 Denizli, Turkey
429-444
A New Method for Gas Effective Diffusion Coefficient Measurement in Water-Saturated Porous Rocks under High Pressures
A new method for determining the gas effective diffusion coefficient in brine-saturated porous rocks was developed on the basis of the radial diffusion model. The experiment was conducted in a high-pressure diffusion cell containing a brine-saturated porous column in the middle and gas in the annulus between the porous column and the cell. The two end faces of the porous column were sealed and the gas diffused into the column only through the radial direction. A small-pressure decay technique was employed to measure the amount of gas diffused into the column as a function of time. A mathematical model was derived to determine the effective diffusion coefficient from the measured pressure decay. To test the presented method, eight measurements were made for CO2 diffusing into brine-saturated Berea and Benthiemer rock plugs at a pressure range of 2.4 to 7.3 MPa. The results are compared with the limited data in the literature.
Zhaowen
Li
Faculty of Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan, S4S 0A2 Canada
Mingzhe
Dong
School of Petroleum Engineering, China University of Petroleum (East China), Qingdao
266580, People's Republic of China; Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
Shuliang
Li
Faculty of Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan, S4S 0A2 Canada
Liming
Dai
Faculty of Engineering, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan, S4S 0A2 Canada
445-461
MHD Instability of Rotating Superposed Walters B′ Viscoelastic Fluids through a Porous Medium
The Rayleigh−Taylor instability of Walters B′ viscoelastic fluids in a porous medium in the presence of uniform rotation and a variable magnetic field is considered. The magnetic field, viscosity, viscoelasticity, and density are assumed to be exponentially varying. For stable density stratification, the system is found to be stable for disturbances of wave numbers subject to the condition that v′0 < k1⁄ε. The magnetic field stabilizes the potentially unstable stratification for small wave-length perturbations which are otherwise unstable. The long wave-length perturbations remain unstable and are not stabilized by a magnetic field. Rotation does not affect the stability or instability, as such, of a stratification.
Pardeep
Kumar
Department of Mathematics, International Centre for Distance Education and Open Learning (ICDEOL), Himachal Pradesh University, Shimla-171005, India
Roshan
Lal
Department of Mathematics, ICDEOL, Himachal Pradesh University, Shimla-171005, India
Gursharn Jit
Singh
Satish Chand Dhawan Government College (SCD), Ludhiana, Punjab, India
463-468
Development of a Cylindrical Porous-Medium Burner
An experimental investigation was performed to address the performance of a radial flow porous burner, fabricated from a ceramic-fiber lamellar structure with circular corrugated layers being sleeved around a perforated tube. The burner lean operation with porous medium was extended to 0.74 in terms of equivalence ratio for a methane-air mixture and burning capacities 1.7 times those with a free flame. The results indicated locally elevated flame temperatures close to the burner's submerged holes and a superior radiation performance, substantiated by a radiation efficiency of 37%. NOx levels as low as 29 ppm were obtained with a maximum CO value around 4000 ppm. Swirl was imparted through a variable-speed motor to enhance turbulence and mutual heat transfer between the gas and solid phases. Only free flames responded to rotary radial flames with extension in flame stability.
M. M.
Kamal
Department of Mechanical Power Engineering, Ain Shams University, Cairo, Abdo Basha Street, 1, Egypt
469-481
Immobilization of 137Cs and 60Co in a Concrete Matrix. Part Two: Mathematical Modeling of Transport Phenomena
Our previous work has evaluated the leaching of 137Cs and 60Co from a waste composite into a surrounding fluid and the determination of retardation factors, KF, and coefficients of distribution, kd, using a simplified mathematical model for analyzing the migration of radionuclides. In our experiment, we have analyzed the mechanism of 137Cs and 60Co leaching values during a period of 60 days. Particularly, we have investigated here the latter modified scenario. Transport phenomena involved in the leaching of a radioactive material from a cement composite matrix are investigated using an empirical method employing a polynomial equation. Results presented in this paper are examples of results obtained in a 25-year mortar and concrete testing project, which will influence the design of the engineered trenches system for a future central Serbian radioactive waste storage center.
Ilija
Plecas
VINCA Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia and Montenegro
Slavko
Dimovic
VINCA Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia and Montenegro
483-489