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Multiphase flow and mass transport through porous mediaSnyder, Kevin P. 17 January 2009 (has links)
The migration of organic contaminants in the subsurface, due to leaking underground storage tanks, includes both discrete and dissolved phase plume movements through the porous media. Such problems always involve the multiphase flow and mass transport through three phases, namely air, oil, and water. A finite element model is developed in this thesis based on the theory of multiphase flow weakly-coupled with the theory of mass transport, in a three-dimensional setting. Galerkin's method is employed to derive the finite element formulations for multiphase flow and mass transport based on the appropriate governing differential equations. The equations for multiphase flow are based on van Genuchten's model for unsaturated flow for air and water. In this model, the saturation-pressure-conductivity relations are used to obtain the constitutive behavior. The solution procedure of the resulting time dependent nonlinear equation involves using a general 0-scheme, for time integration, and a modified Picard's method, for nonlinear iteration. The governing equation for mass transport in a three-phase system is derived based on the assumption of linear partitioning between the air, oil, water, and solid phases. The equations for flow and transport are weakly-coupled through the time lagged interphase mass transfer term. A computer program called IMFTP3D is developed. The program can solve problems related to (1) multiphase immiscible flow, (2) diffusion without flow, and (3) multiphase flow weakly-coupled with mass transport. The three-dimensional model is validated for all three options based on previous two-dimensional models and laboratory experiments present in the literature.
Laboratory experiments where conducted involving gasoline movements through both a one-dimensional column and a two-dimensional flume. The computer program, IMFTP3D, was then used to investigate the usefulness of the model in predicting water outflow in for the column problem and plume movements in the flume experiment. / Master of Science
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The effect of pressure on the performance of flow improvers in slug and annular flow conditionsDunbar, Shaun 01 October 2003 (has links)
No description available.
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Modeling and simulation of volume displacement effects in multiphase flowCihonski, Andrew John 24 September 2013 (has links)
There are many options available when selecting a computational model for
two-phase flows. It is important to understand all the features of the model
selected, including when the model is appropriate and how using it may affect
your results. This work examines how volume displacement effects in two-phase
Eulerian-Lagrangian models manifest themselves. Some test cases are examined
to determine what input these effects have on the flow, and if we can predict
when they will become important. Bubble injection into a traveling vortex ring is
studied in-depth, as it provides significant insight into the physics of these
volume displacement effects. When a few bubbles are entrained into a traveling
vortex ring, it has been shown that even at extremely low volume loadings, their
presence can significantly affect the structure of the vortex core (Sridhar & Katz
1999). A typical Eulerian-Lagrangian point-particle model with two-way coupling
for this dilute system, wherein the bubbles are assumed subgrid and momentum
point-sources are used to model their effect on the flow, is shown to be unable to
accurately capture the experimental trends of bubble settling location, bubble
escape, and vortex distortion for a range of bubble parameters and vortex
strengths. Accounting for fluid volume displacement due to bubble motion, using
a model termed as volumetric coupling, experimental trends on vortex distortion
and bubble settling location are well captured. The fluid displacement effects are
studied by introducing the notion of a volume displacement force, the net force
on the fluid due to volumetric coupling, which is found to be dominant even at
the low volume loadings investigated here. A method of quantifying of these
forces is derived and used to study the effects for a wide range of particle to
fluid density ratios in Taylor-Green vortices. A simple modification to the standard
point-particle Lagrangian approach is developed, wherein the interphase reaction
source terms are consistently altered to account for the fluid displacement effects
and reactions due to bubble accelerations. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Sept. 24, 2012 - Sept. 24, 2013
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Unsteady Multiphase Flow Modeling of In-situ Air Sparging System in a Variably Saturated Subsurface EnvironmentJang, Wonyong 18 November 2005 (has links)
In order to preserve groundwater resources from contamination by volatile organic compounds and to clean up sites contaminated with the compounds, we should understand fate and transport of contaminants in the subsurface systems and physicochemical processes involving remediation technologies. To enhance our understanding, numerical studies were performed on the following topics: (i) multiphase flow and contaminant transport in subsurface environments; (ii) biological transformations of contaminants; (iii) in-situ air sparging (IAS); and, thermal-enhanced venting (TEV). Among VOCs, trichloroethylene (TCE) is one of the most-frequently-detected chemicals in the contaminated groundwater. TCE and its daughter products (cis-1,2-dichloroethylene (cDCE) and vinyl chloride (VC)) are chosen as target contaminants.
Density-driven advection of gas phase is generated by the increase in gas density due to vaporization of high-molecular weight contaminants such as TCE in the unsaturated zone. The effect of the density-driven advection on fate and transport of TCE was investigated under several environmental conditions involving infiltration and permeability.
Biological transformations of contaminants can generate byproducts, which may become new toxic contaminants in subsurface systems. Sequential biotransformations of TCE, cDCE, and VC are considered herein. Under different reaction rates for two bioreaction kinetics, temporal and spatial concentration profiles of the contaminants were examined to evaluate the effect of biotransformations on multispecies transport.
IAS injects clean air into the subsurface below the groundwater table to remediate contaminated groundwater. The movement of gas and the groundwater as a multiphase flow in the saturated zone and the removal of TCE by IAS application were analyzed. Each fluid flow under IAS was examined in terms of saturation levels and fluid velocity profiles in a three-dimensional domain. Several scenarios for IAS systems were simulated to evaluate remedial performance of the systems.
TEV was simulated to investigate its efficiency on the removal of a nonaqueous phase liquid in the unsaturated zone under different operational conditions.
For numerical studies herein, the governing equations for multiphase flow, multispecies transport, and heat energy in porous media were developed and solved using Galerkin finite element method. A three-dimensional numerical model, called TechFlowMP model, has been developed.
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Monitoring sand particle concentration in multiphase flow using acoustic emission technologyEl-Alej, Mohamed Essid January 2014 (has links)
Multiphase flow is the simultaneous flow of two or several phases through a system such as a pipe. This common phenomenon can be found in the petroleum and chemical engineering industrial fields. Transport of sand particles in multiphase production has attracted considerable attention given sand production is a common problem especially to the oil and gas industry. The sand production causes loss of pipe wall thickness which can lead to expensive failures and loss of production time. Build-up of sand in the system can result in blockage and further hamper production. Monitoring of multiphase flow is a process that has been established over several decades. This thesis reports an assessment of the application of Acoustic Emission (AE) technology as an alternative online technique to monitoring of sand particles under multiphase flow conditions in a horizontal pipe. The research was conducted on a purpose built test rig with the purpose of establishing a relation between AE activity and sand concentration under different multiphase flow conditions. The investigation consisted of five experimental tests. The initial experiment was performed to provide a basis for the application of AE technology to detect sand particle impact prior to performing tests in multiphase flow conditions. Further investigations are reported on two phase air-sand, water-sand and air- water-sand three-phase flows in a horizontal pipe for different superficial gas velocities (VSG), superficial liquid velocities (VSL) and sand concentrations (SC). The experimental findings clearly showed a correlation exists between AE energy levels and multiphase flow parameters, such as superficial liquid velocity (VSL), superficial gas velocity (VSG), sand concentration and sand minimum transport condition (MTC).
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A study of gas lift on oil/water flow in vertical risersBrini Ahmed, Salem Kalifa January 2014 (has links)
Gas lift is a means of enhancing oil recovery from hydrocarbon reservoirs. Gas injected at the production riser base reduces the gravity component of the pressure drop and thereby, increases the supply of oil from the reservoir. Also, gas injection at the base of a riser helps to mitigate slugging and thus, improving the performance of the topside facility. In order to improve the efficiency of the gas lifting technique, a good understanding of the characteristics of gas-liquid multiphase flow in vertical pipes is very important. In this study, experiments of gas/liquid (air/water) two-phase flows, liquid/liquid of oil/water two-phase flows and gas/liquid/liquid (air/oil/water) three-phase flows were conducted in a 10.5 m high 52 mm ID vertical riser. These experiments were performed at liquid and gas superficial velocities ranging from 0.25 to 2 m/s and ~0.1 to ~6.30 m/s, respectively. Dielectric oil and tap water were used as test fluids. Instruments such as Coriolis mass flow meter, single beam gamma densitometer and wire-mesh sensor (WMS) were employed for investigating the flow characteristics. For the experiments of gas/liquid (air/water) two-phase flow, flow patterns of Bubbly, slug, churn flow regimes and transition regions were identified under the experimental conditions. Also, for flow pattern identification and void fraction measurements, the capacitance WMS results are consistent with those obtained simultaneously by the gamma densitometer. Generally, the total pressure gradient along the vertical riser has shown a significant decrease as the injected gas superficial velocity increased. In addition, the rate of decrease in total pressure gradient at the lower injected gas superficial velocities was found to be higher than that for higher gas superficial velocities. The frictional pressure gradient was also found to increase as the injected gas superficial velocity increased. For oil-water experiments, mixture density and total pressure gradient across the riser were found to increase with increasing water cut (ranging between 0 - 100%) and/or mixture superficial velocity. Phase slip between the oil and water was calculated and found to be significant at lower throughputs of 0.25 and 0.5 m/s. The phase inversion point always takes place at a point of input water cut of 42% when the experiments started from pure oil to water, and at an input water cut of 45% when the experiment’s route started from water to pure oil. The phase inversion point was accompanied by a peak increase of pressure gradient, particularly at higher oil-water mixture superficial velocities of 1, 1.5 and 2 m/s. The effects of air injection rates on the fluid flow characteristics were studied by emphasizing the total pressure gradient behaviour and identifying the flow pattern by analysing the output signals from gamma and WMS in air/oil/water experiments. Generally, riser base gas injection does not affect the water cut at the phase inversion point. However, a slight shift forward for the identified phase inversion point was found at highest flow rates of injected gas where the flow patterns were indicated as churn to annular flow. In terms of pressure gradient, the gas lifting efficiency (lowering pressure gradient) shows greater improvement after the phase inversion point (higher water cuts) than before and also at the inversion point. Also, it was found that the measured mean void fraction reaches its lowest value at the phase inversion point. These void fraction results were found to be consistent with previously published results.
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Development of GPU-based incompressible SPH and application to sloshing problems in the oil industryDickenson, Paul January 2014 (has links)
No description available.
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Two-phase slug flow measurement using ultra-sonic techniques in combination with T-Y junctionsKhalifa, K. M. January 2010 (has links)
The accurate measurement of multiphase flows of oil/water/gas is a critical element
of oil exploration and production. Thus, over the last three decades; the development
and deployment of in-line multiphase flow metering systems has been a major focus
worldwide. Accurate measurement of multiphase flow in the oil and gas industry is
difficult because there is a wide range of flow regimes and multiphase meters do not
generally perform well under the intermittent slug flow conditions which commonly
occur in oil production.
This thesis investigates the use of Doppler and cross-correlation ultrasonic
measurements made in different high gas void fraction flow, partially separated
liquid and gas flows, and homogeneous flow and raw slug flow, to assess the
accuracy of measurement in these regimes.
This approach has been tested on water/air flows in a 50mm diameter pipe facility.
The system employs a partial gas/liquid separation and homogenisation using a T-Y
junction configuration. A combination of ultrasonic measurement techniques was
used to measure flow velocities and conductivity rings to measure the gas fraction. In
the partially separated regime, ultrasonic cross-correlation and conductivity rings are
used to measure the liquid flow-rate. In the homogeneous flow, a clamp-on
ultrasonic Doppler meter is used to measure the homogeneous velocity and combined
with conductivity ring measurements to provide measurement of the liquid and gas
flow-rates. The slug flow regime measurements employ the raw Doppler shift data
from the ultrasonic Doppler flowmeter, together with the slug flow closure equation
and combined with gas fraction obtained by conductivity rings, to determine the
liquid and gas flow-rates.
Measurements were made with liquid velocities from 1.0m/s to 2.0m/s with gas void
fractions up to 60%. Using these techniques the accuracies of the liquid flow-rate
measurement in the partially separated, homogeneous and slug regimes were 10%,
10% and 15% respectively. The accuracy of the gas flow-rate in both the
homogeneous and raw slug regimes was 10%. The method offers the possibility of
further improvement in the accuracy by combining measurement from different
regimes.
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Multiscale transport of mass, momentum and energyXu, Mingtian., 許明田. January 2002 (has links)
published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy
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Nonlinear multiphasic mechanics of soft tissue using finite element methods.Gaballa, Mohamed Abdelrhman Ahmed. January 1989 (has links)
The purpose of the research was to develop a quantitative method which could be used to obtain a clearer understanding of the time-dependent fluid filteration and load-deformation behavior of soft, porous, fluid filled materials (e.g. biological tissues, soil). The focus of the study was on the development of a finite strain theory for multiphasic media and associated computer models capable of predicting the mechanical stresses and the fluid transport processes in porous structures (e.g. across the large blood vessels walls). The finite element (FE) formulation of the nonlinear governing equations of motion was the method of solution for a poroelastic (PE) media. This theory and the FE formulations included the anisotropic, nonlinear material; geometric nonlinearity; compressibility and incompressibility conditions; static and dynamic analysis; and the effect of chemical potential difference across the boundaries (known as swelling effect in biological tissues). The theory takes into account the presence and motion of free water within the biological tissue as the structure undergoes finite straining. Since it is well known that biological tissues are capable of undergoing large deformations, the linear theories are unsatisfactory in describing the mechanical response of these tissues. However, some linear analyses are done in this work to help understand the more involved nonlinear behavior. The PE view allows a quantitative prediction of the mechanical response and specifically the pore pressure fluid flow which may be related to the transport of the macromolecules and other solutes in the biological tissues. A special mechanical analysis was performed on a representative arterial walls in order to investigate the effects of nonlinearity on the fluid flow across the walls. Based on a finite strain poroelastic theory developed in this work; axisymmetric, plane strain FE models were developed to study the quasi-static behavior of large arteries. The accuracy of the FE models was verified by comparison with analytical solutions wherever is possible. These numerical models were used to evaluate variables and parameters, that are difficult or may be impossible to measure experimentally. For instance, pore pressure distribution within the tissue, relative fluid flow; deformation of the wall; and stress distribution across the wall were obtained using the poroelastic FE models. The effect of hypertension on the mechanical response of the arterial wall was studied using the nonlinear finite element models. This study demonstrated that the finite element models are powerful tools for the study of the mechanics of complicated structures such as biological tissue. It is also shown that the nonlinear multiphasic theory, developed in this thesis, is valid for describing the mechanical response of biological tissue structures under mechanical loadings.
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