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  • 1
    Electronic Resource
    Electronic Resource
    Simple Lagrangian formulation of bubbly flow in a turbulent boundary layer (bubbly boundary layer flow) (1997)
    Springer
    Journal of marine science and technology 2 (1997), S. 1-11 
    Details
    ISSN: 1437-8213
    Keywords: two-phase flow ; micro-bubble ; turbulent boundary layer ; Monte Carlo method ; mixing length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract For the theoretical consideration of a system for reducing skin friction, a mathematical model was derived to represent, in a two-phase field, the effect on skin friction of the injection of micro air bubbles into the turbulent boundary layer of a liquid stream. Based on the Lagrangian method, the equation of motion governing a single bubble was derived. The random motion of bubbles in a field initially devoid of bubbles was then traced in three dimensions to estimate void fraction distributions across sections of the flow channel, and to determine local bubble behavior. The liquid phase was modeled on the principle of mixing length. Assuming that the force exerted on the liquid phase was equal to the fluid drag generated by bubble slip, an equation was derived to express the reduction in turbulent shear stress. Corroborating experimental data were obtained from tests using a cavitation tunnel equipped with a slit in the ceiling from which bubbly water was injected. The measurement data provided qualitative substantiation of the trend shown by the calculated results with regard to the skin friction ratio between cases with and without bubble injection as function of the distance downstream from the point of bubble injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245932
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  • 2
    Electronic Resource
    Electronic Resource
    Tetrachlorosilane Consumption in Radio Frequency Glow Discharge (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 509-533 
    Details
    ISSN: 1572-8986
    Keywords: RF SiCl4 discharge ; mass spectrometry ; kinetics ; decomposition ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl 4 and SiCl 4 −O 2 discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl 4 alone and with O 2 were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl 4 and O 2 consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl 4 conversion. On the contrary, the consumption of SiCl 4 in the SiCl 4 +O 2 mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021811316740
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation of Styrene in a Silent Discharge Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 131-151 
    Details
    ISSN: 1572-8986
    Keywords: Styrene ; oxidation ; silent discharge ; plasma ; dielectric barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A silent discharge plasma reactor has been developed to study the oxidation of styrene vapor in argon/oxygen mixtures. A number of analytical techniques were employed to determine the destruction efficiency and to characterize the intermediate products. The destruction efficiency was measured as a function of initial styrene concentration, temperature, and energy density of the plasma. The formation of solid products was observed in most experiments. At low temperature (100°C), the solid deposit was polymeric in nature, while at high temperature (300°C) the solid appeared to be amorphous carbon. A combination of high temperature and high energy density resulted in high destruction efficiency and minimal production of solid films. The destruction efficiency vs. energy density is shown to be more complex than a simple model predicting exponential behavior. Several reasons for the discrepancy are suggested. The “e-folding” energy density for the destruction of styrene is compared to literature values for other organic compounds, measured using similar types of plasma reactors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021812201545
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidation of Dilute Benzene in an Alumina Hybrid Plasma Reactor at Atmospheric Pressure (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 383-394 
    Details
    ISSN: 1572-8986
    Keywords: Nonthermal plasma ; benzene ; Al2O3 ; BaTiO3 ; oxidation ; absorption ; atmospheric pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The combination of plasma discharge and adsorption was examined for oxidation of dilute benzene in air in a plasma reactor packed with a mixture of BaTiO 3 pellets and porous Al 2 O 3 pellets (i.e., an alumina hybrid reactor). The oxidative decomposition of benzene was enhanced by the benzene concentrating on the Al 2 O 3 pellets. Furthermore, there was a higher selectivity to CO 2 in the products from the hybrid than from a plasma reactor packed with BaTiO 3 pellets alone. The presence of the Al 2 O 3 pellets suppressed the formation of N 2 O.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021820403362
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  • 5
    Electronic Resource
    Electronic Resource
    Oxidation and Reduction Processes During NO x Removal with Corona-Induced Nonthermal Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 421-443 
    Details
    ISSN: 1572-8986
    Keywords: Streamer corona ; NO x removal ; nonthermal plasma ; oxidation ; reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper, the NO-to-NO 2 conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO x removal experiments in N 2 +NO x and N 2 +O 2 +NO x gaseous mixtures, it is supposed that the reverse reaction NO 2 +O→NO+O 2 may not only limit NO 2 production in N 2 +NO x mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NO→N 2 +O, induce negligible NO removal provided the O 2 concentration is larger than 3.6%. With adding H 2 O into the reactor, the produced NO 2 per unit removed NO can be significantly reduced due to NO 2 oxidation. NH 3 injection could also significantly decrease the produced NO 2 via NH and NH 2 - related reduction reactions. Almost 100% of NO 2 can be removed in gaseous mixtures of N 2 +O 2 +H 2 O+NO 2 with negligible NO production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021824504271
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  • 6
    Electronic Resource
    Electronic Resource
    An Upgraded Viscous Coupling Measurement Methodology (1997)
    Springer
    Transport in porous media 28 (1997), S. 221-231 
    Details
    ISSN: 1573-1634
    Keywords: viscous coupling ; transport processes ; relative permeablity ; Onsanger relationship ; transport coefficients ; two-phase flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this Note, suggestions are presented about simple but usually ignored ways to enhance the reliability and utility of the otherwise interesting procedures recently studied (e.g. by Zarcone and Lenormand), and independently by Dullien and Dong for obtaining needed information about the relative importance of the role played by viscous coupling phenomena during multiphase flow processes that occur in and the interstices of natural porous media systems. This is done now because of the persistence of so many perplexing questions and contradicting opinions about what has been a controversial subject ever since the appearance of Yuster's watershed paper in 1951. Here, the belief held by at least a few of the currently publishing authorities is embraced, namely that viscous coupling issues will never be fully settled until the indications of the underlying theoretical interpretations can be fully confirmed by laboratory observations, hence a disclosure of even modest ways to achieve data acquisition enhancements is the motivation for what is written in what follows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006596830724
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  • 7
    Electronic Resource
    Electronic Resource
    An Alternative Description of Viscous Coupling in Two-Phase Flow through Porous Media (1997)
    Springer
    Transport in porous media 28 (1997), S. 205-219 
    Details
    ISSN: 1573-1634
    Keywords: two-phase flow ; viscous coupling ; Cocurrent flow ; counter current flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A new formalism is developed to describe the viscous coupling phenomena between two immiscible, flowing fluids in porous media. The formulation is based on the notation of ‘two-phase mixture’ in which the relative motion between an individual phase and the mixture in porous media can be described by a diffusion equation. The present formulation is derived from Darcy's law with cross-terms without making further approximations. However, the new formulation requires fewer effective parameters to be determined experimentally, thus offering a more viable tool for the study of two-phase flow dynamics with viscous coupling in porous media. Moreover, it is found that no new term appears in the present model in cases with and without viscous coupling; instead, the incorporation of viscous coupling only modifies the effective parameters. It can thus be concluded that viscous coupling does not represent a fundamentally new phenomenon within the framework of the present formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006514204336
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  • 8
    Electronic Resource
    Electronic Resource
    On Vaporizing Water Flow in Hot Sub-Vertical Rock Fractures (1997)
    Springer
    Transport in porous media 28 (1997), S. 335-372 
    Details
    ISSN: 1573-1634
    Keywords: heterogeneous fractures ; preferential flow paths ; two-phase flow ; boiling and condensation ; vapor-dominated geothermal reservoirs ; nuclear waste disposal ; numerical simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Water injection into unsaturated fractured rock at above-boiling temperatures gives rise to complex fluid flow and heat transfer processes. Examples include water injection into depleted vapor-dominated geothermal reservoirs, and emplacement of heat-generating nuclear wastes in unsaturated fractured rock. We conceptualize fractures as two-dimensional heterogeneous porous media, and use geostatistical techniques to generate synthetic permeability distributions in the fracture plane. Water flow in hot high-angle fractures is simulated numerically, taking into account the combined action of gravity, capillary, and pressure forces, and conductive heat transfer from the wall rocks which gives rise to strong vaporization. In heterogeneous fractures boiling plumes are found to have dendritic shapes, and to be subject to strong lateral flow effects. Fractures with spatially-averaged homogeneous permeabilities tend to give poor approximations for vaporization behavior and liquid migration patterns. Depending on water flow rates, rock temperature, and fracture permeability, liquid water can migrate considerable distances through fractured rock that is at above-boiling temperatures and be only partially vaporized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006570702193
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  • 9
    Electronic Resource
    Electronic Resource
    Universal Correlation of Nitrogen 1s and Oxygen 1s Photoelectron Binding Energies with Chemical Composition in Nitrogen-Containing Plasma Polymers (1999)
    Springer
    Plasmas and polymers 4 (1999), S. 283-307 
    Details
    ISSN: 1572-8978
    Keywords: Plasma polymers ; oxidation ; XPS ; photoelectron binding energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The incorporation of oxygen into nitrogen-containing plasma deposited polymers was studied by X-ray Photoelectron Spectroscopy (XPS). As the oxygen content of the plasma polymer increased, the binding energy of the N 1s photoelectrons increased. Conversely, the binding energy of the O 1s photoelectrons was inversely proportional to the nitrogen content of the plasma polymer. The data from a large number of samples all obeyed the same “universal” correlations of photoelectron binding energy versus chemical composition. The data were described by the same curve regardless of whether the oxygen was incorporated rapidly into the thin film during plasma deposition or whether the oxygen was added slowly during spontaneous oxidation of the film in air. This implies that the same thermodynamic principles of radical reactions governed the addition of oxygen to the plasma polymer. The shift in the O 1s and N 1s photoelectron binding energies as a function of chemical composition was used to monitor the proximity of nitrogen and oxygen. By contrasting the experimental data with a simple binomial model which described the random addition of oxygen to a lattice containing carbon and nitrogen, we were able to show that oxygen was preferentially added near nitrogen-containing groups in plasma polymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021831527895
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  • 10
    Electronic Resource
    Electronic Resource
    Lattice-Boltzmann simulations of flow through Fontainebleau sandstone (1995)
    Springer
    Transport in porous media 20 (1995), S. 3-20 
    Details
    ISSN: 1573-1634
    Keywords: lattice-Boltzmann simulations ; single-phase flow ; two-phase flow ; Fontainebleau sandstone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract We report preliminary results from simulations of single-phase and two-phase flow through three-dimensional tomographic reconstructions of Fontainebleau sandstone. The simulations are performed with the lattice-Boltzmann method, a variant of lattice-gas cellular-automation models of fluid mechanics. Simulations of single-phase flow on a sample of linear size 0.2 cm yield a calculated permeability in the range 1.0–1.5 darcys, depending on direction, which compares qualitatively well with a laboratory measurement of 1.3 darcys on a sample approximately an order of magnitude larger. The sensitivity of permeability calculations to sample size, grid resolution, and choice of model parameters is quantified empirically. We also present a qualitative study of immiscible two-phase flow in a sample of linear size 0.05 cm; simulations of both drainage and imbibition are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616923
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  • 11
    Electronic Resource
    Electronic Resource
    Generalized relative permeability coefficients during steady-state two-phase flow in porous media, and correlation with the flow mechanisms (1995)
    Springer
    Transport in porous media 20 (1995), S. 135-168 
    Details
    ISSN: 1573-1634
    Keywords: two-phase flow ; relative permeabilities ; ganglion dynamics ; viscous coupling ; coupling indices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A parametric experimental investigation of the coupling effects during steady-state two-phase flow in porous media was carried out using a large model pore network of the chamber-and-throat type, etched in glass. The wetting phase saturation,S 1, the capillary number,Ca, and the viscosity ratio,k, were changed systematically, whereas the wettability (contact angleθ e ), the coalescence factorCo, and the geometrical and topological parameters were kept constant. The fluid flow rate and the pressure drop were measured independently for each fluid. During each experiment, the pore-scale flow mechanisms were observed and videorecorded, and the mean water saturation was determined with image analysis. Conventional relative permeability, as well as generalized relative permeability coefficients (with the viscous coupling terms taken explicitly into account) were determined with a new method that is based on a B-spline functional representation combined with standard constrained optimization techniques. A simple relationship between the conventional relative permeabilities and the generalized relative permeability coefficients is established based on several experimental sets. The viscous coupling (off-diagonal) coefficients are found to be comparable in magnitude to the direct (diagonal) coefficients over board ranges of the flow parameter values. The off-diagonal coefficients (k rij /Μ j ) are found to be unequal, and this is explained by the fact that, in the class of flows under consideration, microscopic reversibility does not hold and thus the Onsager-Casimir reciprocal relation does not apply. Thecoupling indices are introduced here; they are defined so that the magnitude of each coupling index is the measure of the contribution of the coupling effects to the flow rate of the corresponding fluid. A correlation of the coupling indices with the underlying flow mechanisms and the pertinent flow parameters is established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616928
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  • 12
    Electronic Resource
    Electronic Resource
    Dimensional analysis of pore scale and field scale immiscible displacement (1996)
    Springer
    Transport in porous media 22 (1996), S. 53-72 
    Details
    ISSN: 1573-1634
    Keywords: dimensional analysis ; similarity theory ; scaling groups ; two-phase flow ; residual oil saturation ; mobilization of residual oil ; capillary desaturation curves ; capillary forces ; viscous forces ; gravity forces ; macroscopic force balance ; capillary numbers ; immiscible displacement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A basic re-examination of the traditional dimensional analysis of microscopic and macroscopic multiphase flow equations in porous media is presented. We introduce a ‘macroscopic capillary number’ $$\overline {Ca}$$ which differs from the usual microscopic capillary number Ca in that it depends on length scale, type of porous medium and saturation history. The macroscopic capillary number $$\overline {Ca}$$ is defined as the ratio between the macroscopic viscous pressure drop and the macroscopic capillary pressure. $$\overline {Ca}$$ can be related to the microscopic capillary number Ca and the LeverettJ-function. Previous dimensional analyses contain a tacit assumption which amounts to setting $$\overline {Ca}$$ = 1. This fact has impeded quantitative upscaling in the past. Our definition for $$\overline {Ca}$$ , however, allows for the first time a consistent comparison between macroscopic flow experiments on different length scales. Illustrative sample calculations are presented which show that the breakpoint in capillary desaturation curves for different porous media appears to occur at $$\overline {Ca}$$ ≈ 1. The length scale related difference between the macroscopic capillary number $$\overline {Ca}$$ for core floods and reservoir floods provides a possible explanation for the systematic difference between residual oil saturations measured in field floods as compared to laboratory experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00974311
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  • 13
    Electronic Resource
    Electronic Resource
    Mechanistic Model of Steady-State Two-Phase Flow in Porous Media Based on Ganglion Dynamics (1998)
    Springer
    Transport in porous media 30 (1998), S. 267-299 
    Details
    ISSN: 1573-1634
    Keywords: two-phase flow ; ganglion dynamics ; relative permeability ; population balance equations ; oil recovery ; soil remediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Recent experimental work has shown that the pore-scale flow mechanism during steady-state two-phase flow in porous media is ganglion dynamics (GD) over a broad and practically significant range of the system parameters. This observation suggests that our conception and theoretical treatment of fractional flow in porous media need careful reconsideration. Here is proposed a mechanistic model of steady-state two-phase flow in those cases where the dominant flow regime is ganglion dynamics. The approach is based on the ganglion population balance equations in combination with a microflow network simulator. The fundamental information on the cooperative flow behavior of the two fluids at the scale of a few hundred pores is expressed through the system factors, which are functions of the system parameters and are calculated using the simulator. These system factors are utilized by the population balance equations to predict the macroscopic behavior of the process. The dependence of the conventional relative permeability coefficients not only on the wetting fluid saturation Swbut also on the capillary number, Ca, the viscosity ratio κ the wettability (θ0 a, θ0 r), the coalescence factor, Co, as well as the porous medium geometry and topology is explained and predicted on a mechanistic basis. Sample calculations have been performed for steady-state fully developed (SSFD) and steady-state nonfully developed (SSnonFD) flow conditions. The number distributions of the moving and the stranded ganglia, the mean ganglion size, the fraction of the nonwetting fluid in the form of mobile ganglia, the ratio of the conventional relative permeability coefficients and the fractional flows are studied as functions of the system parameters and are correlated with the flow phenomena at pore level and the system factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006558121674
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  • 14
    Electronic Resource
    Electronic Resource
    Determination of permeability tensors for two-phase flow in homogeneous porous media: Theory (1996)
    Springer
    Transport in porous media 24 (1996), S. 107-137 
    Details
    ISSN: 1573-1634
    Keywords: homogeneous porous media ; two-phase flow ; volume averaging ; permeability tensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this paper we continue previous studies of the closure problem for two-phase flow in homogeneous porous media, and we show how the closure problem can be transformed to a pair of Stokes-like boundary-value problems in terms of ‘pressures’ that have units of length and ‘velocities’ that have units of length squared. These are essentially geometrical boundary value problems that are used to calculate the four permeability tensors that appear in the volume averaged Stokes' equations. To determine the geometry associated with the closure problem, one needs to solve the physical problem; however, the closure problem can be solved using the same algorithm used to solve the physical problem, thus the entire procedure can be accomplished with a single numerical code.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00139841
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  • 15
    Electronic Resource
    Electronic Resource
    Experimental determination of the flow transport coefficients in the coupled equations of two-phase flow in porous media (1996)
    Springer
    Transport in porous media 25 (1996), S. 97-120 
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    ISSN: 1573-1634
    Keywords: two-phase flow ; coupled two-phase flow ; hydrodynamic coupling ; transport coefficients ; steady two-phase flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The transport coefficients in the coupled equations of two-phase flow are defined if the pressure gradient in one of the two flowing fluids is equal to zero. This definition has been used in experiments with oil and water in a sandpack and the four transport coefficients have been measured over wide water saturation ranges. The values of the cross coefficients were found to be significant as they ranged from 10 to 35% of the value of the effective permeability to water and from 5 to 15% of the effective permeability to oil, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141264
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  • 16
    Electronic Resource
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    Effects of Relative Permeability History Dependence on Two-Phase Flow in Porous Media (1997)
    Springer
    Transport in porous media 28 (1997), S. 181-203 
    Details
    ISSN: 1573-1634
    Keywords: relative permeability ; hyssteresis ; Riemann problem ; fractional flow ; conservation law ; flow prediction ; history ; immiscible displacement ; two-phase flow ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Hysteresis phenomena in multi-phase flow in porous media has been recognized by many researchers and widely believed to have significant effects on the flow. In an attempt to account for these effects, a theoretical model for history-dependent relative permeabilities is considered. This model is incorporated into 1-D two-phase nondiffusive flow system and the corresponding flow is predicted. Flow history is observed to have a notable impact on the saturation profile and fluids breakthrough.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006556018950
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  • 17
    Electronic Resource
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    Generalized Forchheimer Equation for Two-Phase Flow Based on Hybrid Mixture Theory (1997)
    Springer
    Transport in porous media 26 (1997), S. 261-275 
    Details
    ISSN: 1573-1634
    Keywords: swelling porous media ; high velocity flow ; non-Darcy flow ; two-phase flow ; multi-phase flow ; mixture theory ; Forchheimer equation ; unsaturated flow ; Darcy's law ; non-linear flow ; hybrid mixture theory ; isotropic function theory.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this paper, we derive a Forchheimer-type equation for two-phase flow through an isotropic porous medium using hybrid mixture theory. Hybrid mixture theory consists of classical mixture theory applied to a multiphase system with volume averaged equations. It applies to media in which the characteristic length of each phase is ‘small’ relative to the extent of the mixture. The derivation of a Forchheimer equation for single phase flow has been obtained elsewhere. These results are extended to include multiphase swelling materials which have nonnegligible interfacial thermodynamic properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006536424162
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  • 18
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    A Two-Dimensional Network Simulator for Two-Phase Flow in Porous Media (1998)
    Springer
    Transport in porous media 32 (1998), S. 163-186 
    Details
    ISSN: 1573-1634
    Keywords: network modeling ; immiscible ; drainage displacement ; two-phase flow ; capillary and viscous forces ; pressure simulations ; scaling exponents ; front width ; time dependences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract We investigate a two-dimensional network simulator that model the dynamics of drainage dominated flow where film flow can be neglected. We present a new method for simulating the temporal evolution of the pressure due to capillary and viscous forces in the displacement process. To model the dynamics, we let the local capillary pressure change as if the menisci move in and out of hour-glass shaped tubes. Furthermore, a method has been developed to allow simultaneous flow of two liquids into one tube. The model is suitable to simulate different time dependencies in two-phase drainage displacements. In this paper, we simulate the temporal evolution of the fluid pressures and analyze the time dependence of the front between the two liquids. The front width was found to be consistent with a scaling relation w ∝ tβ h(t/ts). The dynamical exponent, β, describing the front width evolution as function of time, was estimated to β = 1.0. The results are compared to experimental data of Frette and co-workers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006510106194
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  • 19
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    Estimates of Barometric Pumping of Moisture Through Unsaturated Fractured Rock (1999)
    Springer
    Transport in porous media 36 (1999), S. 85-119 
    Details
    ISSN: 1573-1634
    Keywords: barometric pumping ; two-phase flow ; fractured rock.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract We present a theory for the motion of water vapor at depth in a discretely fractured permeable medium induced by atmospheric barometric pressure fluctuations, or ‘barometric pumping’. The theory involves multiphase mass and energy transport in a fracture/matrix system, with discrete representation of the fracture system. The barometric pressure fluctuations are approximated as periodic in time, with amplitude corresponding to measured values. To simplify the analysis, a ‘single-horizon’ approximation is applied in which the time-mean gradient is used to evaluate the vertical advective flux in the fractures. Time-periodic solutions are obtained numerically, enabling the calculation of the net efflux of moisture per cycle. The model is applied to material representative of the Yucca Mountain region of southwestern Nevada. The results indicate that the efflux of moisture carried upward from significant depths by barometric pumping is much less than the near surface efflux that is commonly estimated by assuming that air enters the medium dry and is returned to the atmosphere fully saturated with water vapor. This near surface efflux consists primarily of moisture discharged from the upper layer which is frequently replenished by precipitation. Of greater interest to nuclear waste repository design and estimations of net infiltration in arid regions is the fraction of the total moisture efflux that comes from significant depths. This deep transport is quantified by the fracture/matrix transport model described here. Although the transport by barometric pumping from depth is small compared to the total moisture expelled from the surface layer, it is an order of magnitude greater than the vertical moisture flux carried from depth by diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006593628835
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  • 20
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    The Manufacture of Continuous Smelting Electrodes from Carbon-Paste Briquettes (1998)
    Springer
    Journal of engineering mathematics 33 (1998), S. 353-376 
    Details
    ISSN: 1573-2703
    Keywords: two-phase flow ; viscous-dominated flow ; free-boundary problems ; continuous electrodes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract Continuously consumed electrodes are used in the manufacture of ferro alloys, aluminium, silicon metal and calcium carbide. The raw material for the electrodes is a carbon paste which is normally added to the electrode in large solid sections. The option of manufacturing such electrodes from small paste ‘briquettes’ is examined with respect to an industrial experiment used to predict the quality of a briquette-formed electrode. It is shown that successful predictive models may be formulated using a two-phase slow-flow approach. Consideration is also given to the briquette manufacture of Persson and Bruff electrodes, two different commercially important devices for the production of silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004317014216
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  • 21
    Electronic Resource
    Electronic Resource
    A deflagration analysis of porous energetic materials with two-phase flow and a multiphase sequential reaction mechanism (1997)
    Springer
    Journal of engineering mathematics 31 (1997), S. 173-203 
    Details
    ISSN: 1573-2703
    Keywords: deflagration ; two-phase flow ; porous materials ; activation energy ; asymptotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract A theoretical analysis for the unconfined deflagration of a porous energetic material is developed for a two-step global reaction mechanism that consists of the condensed-phase combustion of the reactive material to produce gas-phase intermediates, followed by a gas-phase reaction that produces final gas-phase products. An asymptotic approach is employed, leading to explicit formulas for the deflagration velocity in specific parameter regimes. The results clearly indicate the influences of two-phase flow and the multiphase, multi-step chemistry on the burning rate, and serve to further characterize the combustion behavior of a significant class of degraded nitramine-type propellants for which the present analysis is applicable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004239528221
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