Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
16
12
2013
INSTABILITY OF HYDROMAGNETIC FLUIDS STREAMING IN A POROUS MEDIUM WITH SUSPENDED DUST PARTICLES
The Rayleigh−Taylor (R-T) and Kelvin−Helmholtz (K-H) instabilities of a plasma are discussed in a porous medium with a horizontal magnetic field and suspended dust particles. The medium is assumed to be incompressible. The linearized hydromagnetic equations are solved, and a dispersion relation for such a medium has been obtained using appropriate boundary conditions. We find that the dispersion relation is modified owing to the simultaneous presence of a magnetic field, porosity, and suspended particles. The instability criterion for the medium is derived, which is found to be independent of the presence of the suspended dust particles. Similarly, conditions of R-T and K-H instability of the system are also derived for the present porous medium.
Praveen K.
Sharma
BUIT, Barkatullah University Bhopal (M.P.)-462026, India
Anita
Tiwari
BUIT, Barkatullah University Bhopal (M.P.)-462026, India
Rajendra K.
Chhajlani
School of Studies in Physics, Vikram University Ujjain (M.P.)-456010, India
1063-1074
A STUDY OF CONFIGURATIONS OF CLAY-GLASS BEADS MIXTURE TO DETERMINE THE INFLUENCE OF COMPOSITION AND COMPACTION PRESSURE ON THE RETENTION OF NITRATE
In compacted Na-montmorillonite membranes, the pore size and surface charge will influence filtration processes of solutes. A dead-end hyperfiltration setup was utilized to (1) study the intrinsic retention, membrane filtration coefficient, and solution flux of different membrane configurations and (2) model nitrate breakthrough effluent concentrations through the membrane. Scanning electron microscopy and solute analytical techniques were employed to assess what critical components at micrometer scale would prevail in a non-bio-stimulated remediation of simulated agricultural wastewater. The results reveal hyperfiltration of nitrate ions is a function of the compaction pressure and composition of bentonite in the mixed soils. Although high-content bentonite membrane configurations (5 g clay at 2500 psi) offered better solute rejections with a 30% increase in the cell concentration, the compaction of the membrane had the most deterministic influence on the solution flux. We can adduce that for permselective membranes, it is more probable that a size exclusion mechanism predominates ion exclusion in solute sieving.
Anthony W.
Wamono
Environmental and Conservation Sciences, North Dakota State University, P.O. Box 6050, Fargo, ND 58108, USA
Peter G.
Oduor
Department of GeoSciences, North Dakota State University, P.O. Box 6050, Fargo, ND 58108, USA
1075-1086
STEADY SOLUTE DISPERSION IN COMPOSITE POROUS MEDIUM BETWEEN TWO PARALLEL PLATES
The Taylor dispersion of a solute for a composite porous medium between two parallel plates is studied analytically. The fluids in both the regions are incompressible and the transport properties are assumed to be constant. The closed-form solutions are obtained in both fluid regions of the channel. The results are presented graphically for various values of porosity, pressure gradient, height of the channel, viscosity, and diffusivity on the concentration. The volumetric flow rate in the channel for variation of viscosity, height, and porous parameter is also found. The validity of the results obtained for composite porous media is verified by comparison with the available porous medium results in the literature for one fluid model, and good agreement is found.
J. Prathap
Kumar
Department of Mathematics, Gulbarga University, Gulbarga-585 106, Karnataka
Jawali
Umavathi
Gulbarga University
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Mohammad Bin Fahd University, P.O. Box
1664, Al-Khobar 31952, Kingdom of Saudi Arabia;
Prince Sultan Endowment for Energy and Environment, Prince Mohammad Bin Fahd
University, Al-Khobar 31952, Saudi Arabia
1087-1105
MIXED CONVECTION OF MICROPOLAR FLUIDS IN A VERTICAL WAVY CHANNEL SATURATED WITH POROUS MEDIA
Combined convection of micropolar fluids in a vertical wavy channel saturated with porous media was studied. The coordinate transformation scheme was employed for the numerical calculation. The numerical results predict that the implicit properties of micropolar fluid influence the flow resistance and the heat transfer rate in the channel. Furthermore, as the heated surface is bulged and sunken periodically, the corrugated boundary conditions cause change to the flow fields with further influence on heat transfer efficiency. This article also finds that the increased heat transfer areas by corrugation are sufficient to counteract the heat resistance caused by flowing inconvenience. Therefore all the heat transfer efficiency of wavy channels is higher than that for flat ones. For higher Reynolds numbers, faster flowing velocities in the trough walls result in higher Nusselt numbers. Because the porous media may provide available contact surface areas between both solid and liquid for heat transfer, the channel saturated with porous media enlarges the effect of heat transfer. When the Darcy number is increased, both the surface friction and vortex resistance decrease. In addition, the velocities and heat transfer nearby the wavy wall also decrease. However, the heat transfer efficiency of channel flow saturated with porous media is higher than that of singlephase fluid flow.
K. Y.
Hung
Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Jiangong Road, Sanmin District, Kaohsiung 80778, Taiwan, R.O.C.
Tsna-Hui
Hsu
Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Jiangong Road, Sanmin District, Kaohsiung 80778, Taiwan, R.O.C.
J. W.
Lin
Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Jiangong Road, Sanmin District, Kaohsiung 80778, Taiwan, R.O.C.
1107-1118
HEATLINE VISUALIZATION OF CONJUGATE HEAT TRANSFER IN SQUARE POROUS ENCLOSURE
Conjugate natural convection-conduction heat transfer in a square porous enclosure filled with a fluid-saturated porous medium is studied numerically in the present article. Complete numerical simulations of the two enclosures, one with bounded conductive walls and the other with a partitioned conductive wall, are carried out. The analysis is performed in the following ranges of the associated dimensionless groups: the wall thickness, 0.0 ≤ D ≤ 1.0, the thermal conductivity ratio, 0.1 ≤ Kr ≤ 10.0, the porosity, 0.4 ≤ ε ≤ 0.99, and the Darcy number, 10−3 ≤ Da ≤ 5 × 10−2. Optimal combinations of the wall thickness, thermal conductivity ratio, porosity, and Darcy number to control the fluid flow and thermal performance of both enclosures were obtained.
Habibis
Saleh
School of Mathematical Sciences, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor, Malaysia
I
Hashim
1119-1132
ANALYSIS OF THE CYLINDRICAL MAGNETIC COUETTE FLOW IN A RADIALLY MAGNETIZED THIN POROUS ANNULUS
This work seeks the steady-state solution for a magnetic fluid filling a thin porous annulus between two moving cylindrical walls under the influence of a radially outward magnetic field. The cylinders were either perfectly insulated or perfectly conducting. Current results show that there will be an invariant point independent of the strength of magnetic and flow fields if both cylinders are insulated. This point may shift toward the inner cylinder as the permeability increases. When the inner cylinder is insulated while the outer one is perfectly conducting, the velocity close to the inner cylinder decreases with the strength of the external magnetic field. At the same time, a reverse flow is found close to the outer cylinder after being pushed by its local clockwise Lorentz force. When the inner cylinder is perfectly conducting and the outer cylinder is insulated, the current density surrounding the inner cylinder reduces while that next to the outer cylinder increases. This leads to a special phenomenon where the magnetic fluid actually flows faster as the strength of the external magnetic field increases.
Kong-Fue
Lin
Department of Vehicle Engineering, National Pingtung University of Science and Technology, Taiwan, ROC
Jik-Chang
Leong
Department of Vehicle Engineering, National Pingtung University of Science and Technology, Taiwan, ROC
1133-1146