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Sally M. Benson - One of the best experts on this subject based on the ideXlab platform.
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pore scale Capillary Pressure analysis using multi scale x ray micromotography
Advances in Water Resources, 2017Co-Authors: Charlotte Garing, Jacques A De Chalendar, Marco Voltolini, Jonathan B Ajofranklin, Sally M. BensonAbstract:Abstract A multi-scale synchrotron-based X-ray microtomographic dataset of residually trapped air after gravity-driven brine imbibition was acquired for three samples with differing pore topologies and morphologies; image volumes were reconstructed with voxel sizes from 4.44 µm down to 0.64 µm. Capillary Pressure distributions among the population of trapped ganglia were investigated by calculating interfacial curvature in order to assess the potential for remobilization of residually-trapped non-wetting ganglia due to differences in Capillary Pressure presented by neighbor ganglia. For each sample, sintered glass beads, Boise sandstone and Fontainebleau sandstone, sub-volumes with different voxel sizes were analyzed to quantify air/brine interfaces and interfacial curvatures and investigate the effect of image resolution on both fluid phase identification and curvature estimates. Results show that the method developed for interfacial curvature estimation leads to reliable Capillary Pressure estimates for gas ganglia. Higher resolution images increase confidence in curvature calculations, especially for the sandstone samples that display smaller gas-brine interfaces which are then represented by a higher number of voxels when imaged with a micron or sub-micron voxels size. The analysis of sub-volumes from the Boise and Fontainebleau dataset highlights the presence of a residually-trapped gas phase consisting of ganglia located in one or few pores and presenting significantly different Capillary Pressures, especially in the case of Fontainebleau sandstone. As a result, Ostwald ripening could occur, leading to gas transfer from ganglia with higher Capillary Pressure to surrounding ganglia with lower Capillary Pressures. More generally, at the pore-scale, most gas ganglia do present similar Capillary Pressures and Ostwald ripening would then not represent a major mechanism for residually-trapped gas transfer and remobilization.
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Influence of Capillary-Pressure models on CO2 solubility trapping
Advances in Water Resources, 2013Co-Authors: Hamdi A. Tchelepi, Sally M. BensonAbstract:Abstract The typical shape of a Capillary-Pressure curve is either convex (e.g., Brooks–Corey model) or S-shaped (e.g., van Genuchten model). It is not universally agreed which model reflects natural rocks better. The difference between the two models lies in the representation of the Capillary entry Pressure. This difference does not lead to significantly different simulation results for modeling CO2 sequestration in aquifers without considering CO2 dissolution. However, we observe that the van-Genuchten-type Capillary-Pressure model accelerates CO2 solubility trapping significantly compared with the Brooks–Corey-type model. We also show that the simulation results are very sensitive to the slope of the van-Genuchten-type curve around the entry-Pressure region. For the representative examples we study, the differences can be so large as to have complete dissolution of the CO2 plume versus persistence of over 50% of the plume over a 5000-year period. The cause of such sensitivity to the Capillary-Pressure model is studied. Particularly, we focus on how the entry Pressure is represented in each model. We examine the mass-transfer processes under gravity-Capillary equilibrium, molecular diffusion, convective mixing, and in the presence of small-scale heterogeneities. Laboratory measurement of Capillary-Pressure curves and some important implementation issues of Capillary-Pressure models in numerical simulators are also discussed. Most CO2 sequestration simulations in the literature employ one of the two Capillary-Pressure models. It is important to recognize that these two representations lead to very different predictions of long-term CO2 sequestration.
Ulrich K. Franzeck - One of the best experts on this subject based on the ideXlab platform.
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diurnal and long term variations of lymph Capillary Pressure in health
European Journal of Plastic Surgery, 1998Co-Authors: J Dorfflermelly, D Schild, A Bollinger, Ulrich K. FranzeckAbstract:The variability of Pressure in the cutaneous lymph capillaries on the forefoot was determined in 2 groups of healthy volunteers. In group A, including 12 subjects (8 men, 4 women; mean age 28 years, range 22 to 37 years) measurements were performed in the morning and late afternoon of the same day. In group B (12 subjects, 5 women, 7 men; mean age 53 years, range 23 to 72 years) measurements of lymph Capillary Pressure were repeated within an interval of 7 weeks. The superficial microlymphatics were visualized by intravital fluorescence microlymphography, cannulated with glass micropipettes, and the lymph Capillary Pressure was measured using a servo-nulling Pressure system. The lymph Capillary Pressure measured in the morning (mean 7.5±4.4 mm Hg; range −4 to 16 mm Hg) did not differ (p>0.05) from the Pressure in the late afternoon (mean value 5.6±3.4 mm Hg; range −1 to 13 mm Hg). In group B initial lymph Capillary Pressure (mean 3.9±2.9 mm Hg, range −1.1 to 9.7 mm Hg) was not different (p>0.05) compared to the Pressure after 7 weeks (2.9±2.7 mm Hg; range −1.0 to 6.8 mm Hg). In conclusion, lymph Capillary Pressure in healthy subjects does not exhibit significant changes during the daytime and the long-term reproducibility is good.
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diurnal and long term variations of lymph Capillary Pressure in healthy subjects
Lymphology, 1997Co-Authors: J Dorfflermelly, D Schild, A Bollinger, Ulrich K. FranzeckAbstract:The variability of Pressure in the cutaneous lymph capillaries on the forefoot was determined in 2 groups of healthy volunteers. In group A, including 12 healthy subjects (8 men, 4 women; mean age 28 years, range 22 to 37 years), measurements were performed in the morning and late afternoon of the same day. In group B (12 healthy subjects, 5 women, 7 men; mean age 53 years, range 23 to 72 years), measurements of lymph Capillary Pressure were repeated with an interval of 7 weeks. The superficial microlymphatics were visualized by intravital fluorescence microlymphography, cannulated with glass micropipettes, and the lymph Capillary Pressure was measured using a servonulling Pressure system. In group A, lymph Capillary Pressure measured in the morning (mean 7.5 +/- 4.4 mmHg; range -4 to 16 mmHg) did not differ (p > 0.05) from the Pressure in the late afternoon (mean value 5.6 +/- 3.4 mmHg; range-1 to 13 mmHg). In group B, initial lymph Capillary Pressure (mean 3.9 +/- 2.9 mmHg, range -1.1 to 9.7 mmHg) was not different (p > 0.05) compared with the Pressure after 7 weeks (2.9 +/- 2.7 mmHg, range -1.0 to 6.8 mmHg). We conclude that lymph Capillary Pressure in healthy subjects does not exhibit significant changes during the daytime or over the long term.
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effect of postural changes on human lymphatic Capillary Pressure of the skin
The Journal of Physiology, 1996Co-Authors: Ulrich K. Franzeck, U Costanzo, I Herrig, M. Fischer, Alfred BollingerAbstract:1. The influence of postural changes on cutaneous lymphatic Capillary Pressure and venous Pressure was measured at the dorsum of the foot in twelve healthy volunteers. Measurements were performed in the supine and sitting positions. 2. Lymphatic skin capillaries were visualized by fluorescence microlymphography with fluorescein isothiocyanate (FITC)-Dextran 150000. Subsequently a lymphatic Capillary was punctured with a glass micropipette and Pressure was measured using the servo-nulling technique. Lymphatic Capillary Pressure, venous Pressure, heart and respiration rates were recorded simultaneously. 3. Mean lymphatic Capillary Pressure was significantly higher (P = 0.0096) in the sitting (9.9 +/- 3.0 mmHg) than in the supine (3.9 +/- 4.2 mmHg) position. There was no significant difference (P = 0.09) between lymphatic Capillary Pressure and venous Pressure (6.8 +/- 3.4 mmHg) in the supine position. During sitting mean lymphatic Capillary Pressure was significantly lower (P = 0.0022) than mean venous Pressure (53.3 +/- 4.1 mmHg). The smaller increase in lymphatic Capillary Pressure may be caused by the discontinuous fluid column in the lymphatic system and enhanced orthostatic contractile activity of lymphatic collectors and precollectors. Spontaneous low frequency Pressure fluctuations occurred in 89% of recordings during sitting, which was significantly (P = 0.02) higher than in the supine position (54%). 4. The present results support the suggestion of enhanced intrinsic contractile activity of lymph precollectors and collectors in the dependent position. This mechanism is primarily responsible for the propulsion of lymph from the periphery to the thoracic duct during quiet sitting, when extrinsic pumping by the calf muscles is not active.
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lymphatic Capillary Pressure in patients with primary lymphedema
Microvascular Research, 1993Co-Authors: Beatrice R Zauggvesti, J Dorfflermelly, Ulrich K. Franzeck, Michael Spiegel, Alfred BollingerAbstract:Flow and Pressure dynamics in minute human lymphatics are unexplored. Lymphatic Capillary Pressure was measured by the servo-nulling technique at the foot dorsum of 14 patients with primary lymphedema and 15 healthy controls. Glass micropipettes (7-9 μm) were inserted under microscopic control into lymphatic microvessels previously stained by fluorescence microlymphography (FITC-Dextran 150,000). Mean lymphatic Capillary Pressure was 7.9 ± 3.4 mm Hg in the controls and 15.0 ± 5.1 mm Hg in the patients. The difference was significant at the P < 0.001 level. In about half of the patients and control subjects studied Pressure fluctuated by more than 3 mm Hg. The mean intralymphatic Pressure of lymphedema patients was slightly below mean interstitial Pressure measured by J. T. Christensen, N. J. Shaw, M. M. Hamas and H. K. Al Hassan (1985, Microcirc., Endothelium, Lymphatics2, 267-384) (17.9 mm Hg) in lower leg lymphedema. Microlymphatic hypertension present in patients with primary lymphedema is probably an important factor for edema formation.
Alfred Bollinger - One of the best experts on this subject based on the ideXlab platform.
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effect of postural changes on human lymphatic Capillary Pressure of the skin
The Journal of Physiology, 1996Co-Authors: Ulrich K. Franzeck, U Costanzo, I Herrig, M. Fischer, Alfred BollingerAbstract:1. The influence of postural changes on cutaneous lymphatic Capillary Pressure and venous Pressure was measured at the dorsum of the foot in twelve healthy volunteers. Measurements were performed in the supine and sitting positions. 2. Lymphatic skin capillaries were visualized by fluorescence microlymphography with fluorescein isothiocyanate (FITC)-Dextran 150000. Subsequently a lymphatic Capillary was punctured with a glass micropipette and Pressure was measured using the servo-nulling technique. Lymphatic Capillary Pressure, venous Pressure, heart and respiration rates were recorded simultaneously. 3. Mean lymphatic Capillary Pressure was significantly higher (P = 0.0096) in the sitting (9.9 +/- 3.0 mmHg) than in the supine (3.9 +/- 4.2 mmHg) position. There was no significant difference (P = 0.09) between lymphatic Capillary Pressure and venous Pressure (6.8 +/- 3.4 mmHg) in the supine position. During sitting mean lymphatic Capillary Pressure was significantly lower (P = 0.0022) than mean venous Pressure (53.3 +/- 4.1 mmHg). The smaller increase in lymphatic Capillary Pressure may be caused by the discontinuous fluid column in the lymphatic system and enhanced orthostatic contractile activity of lymphatic collectors and precollectors. Spontaneous low frequency Pressure fluctuations occurred in 89% of recordings during sitting, which was significantly (P = 0.02) higher than in the supine position (54%). 4. The present results support the suggestion of enhanced intrinsic contractile activity of lymph precollectors and collectors in the dependent position. This mechanism is primarily responsible for the propulsion of lymph from the periphery to the thoracic duct during quiet sitting, when extrinsic pumping by the calf muscles is not active.
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lymphatic Capillary Pressure in patients with primary lymphedema
Microvascular Research, 1993Co-Authors: Beatrice R Zauggvesti, J Dorfflermelly, Ulrich K. Franzeck, Michael Spiegel, Alfred BollingerAbstract:Flow and Pressure dynamics in minute human lymphatics are unexplored. Lymphatic Capillary Pressure was measured by the servo-nulling technique at the foot dorsum of 14 patients with primary lymphedema and 15 healthy controls. Glass micropipettes (7-9 μm) were inserted under microscopic control into lymphatic microvessels previously stained by fluorescence microlymphography (FITC-Dextran 150,000). Mean lymphatic Capillary Pressure was 7.9 ± 3.4 mm Hg in the controls and 15.0 ± 5.1 mm Hg in the patients. The difference was significant at the P < 0.001 level. In about half of the patients and control subjects studied Pressure fluctuated by more than 3 mm Hg. The mean intralymphatic Pressure of lymphedema patients was slightly below mean interstitial Pressure measured by J. T. Christensen, N. J. Shaw, M. M. Hamas and H. K. Al Hassan (1985, Microcirc., Endothelium, Lymphatics2, 267-384) (17.9 mm Hg) in lower leg lymphedema. Microlymphatic hypertension present in patients with primary lymphedema is probably an important factor for edema formation.
Michael A Celia - One of the best experts on this subject based on the ideXlab platform.
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Dynamic effect in the Capillary Pressure–saturation relationship and its impacts on unsaturated flow
2015Co-Authors: Majid S Hassanizadeh, Michael A Celia, Helge K DahleAbstract:ABSTRACT where Pn and Pw are the average Pressures of nonwetting and wetting phases, respectively; Pc is Capillary Pressure,Capillary Pressure plays a central role in the description of water and S is the wetting phase saturation. A schematic depic-flow in unsaturated soils. While capillarity is ubiquitous in unsaturated tion of Pc vs. S curves is given in Fig. 1.analyses, the theoretical basis and practical implications of capillarity This simple model is implicitly assumed to account forin soils remain poorly understood. In most traditional treatments of Capillary Pressure, it is defined as the difference between Pressures all effects and processes that influence the equilibrium of phases, in this case air and water, and is assumed to be a function distribution of fluids, such as surface tension, presence of saturation. Recent theories have indicated that Capillary Pressure of fluid–fluid interfaces, wettability of solid surfaces, should be given a more general thermodynamic definition, and its grain size distribution, and microscale heterogeneities. functional dependence should be generalized to include dynamic ef- All of these effects are essentially lumped into the Pc–S fects. Experimental evidence has slowly accumulated in the past de- relationship. Moreover, this relationship and graphscades to support a more general description of Capillary Pressure that similar to those depicted in Fig. 1 are obtained experi-includes dynamic effects. A review of these experiments shows that mentally under equilibrium conditions. Thus, to obtainthe coefficient arising in the theoretical analysis can be estimated from a drainage (or imbibition) curve, one starts with a wetthe reported data. The calculated values range from 104 to 107 kg (or dry) soil sample, then the Capillary Pressure is in-(m s)1. In addition, recently developed pore-scale models that simu
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Dynamic effect in the Capillary Pressure-saturation relationship and its impacts on unsaturated flow
2015Co-Authors: Majid S Hassanizadeh, Michael A Celia, Helge K DahleAbstract:ABSTRACT where Pn and Pw are the average Pressures of nonwetting and wetting phases, respectively; Pc is Capillary Pressure,Capillary Pressure plays a central role in the description of water and S is the wetting phase saturation. A schematic depic-flow in unsaturated soils. While capillarity is ubiquitous in unsaturated tion of Pc vs. S curves is given in Fig. 1.analyses, the theoretical basis and practical implications of capillarity This simple model is implicitly assumed to account forin soils remain poorly understood. In most traditional treatments of Capillary Pressure, it is defined as the difference between Pressures all effects and processes that influence the equilibrium of phases, in this case air and water, and is assumed to be a function distribution of fluids, such as surface tension, presence of saturation. Recent theories have indicated that Capillary Pressure of fluid–fluid interfaces, wettability of solid surfaces, should be given a more general thermodynamic definition, and its grain size distribution, and microscale heterogeneities. functional dependence should be generalized to include dynamic ef- All of these effects are essentially lumped into the Pc–S fects. Experimental evidence has slowly accumulated in the past de- relationship. Moreover, this relationship and graphscades to support a more general description of Capillary Pressure that similar to those depicted in Fig. 1 are obtained experi-includes dynamic effects. A review of these experiments shows that mentally under equilibrium conditions. Thus, to obtainthe coefficient arising in the theoretical analysis can be estimated from a drainage (or imbibition) curve, one starts with a wetthe reported data. The calculated values range from 104 to 107 kg (or dry) soil sample, then the Capillary Pressure is in-(m s)1. In addition, recently developed pore-scale models that simu
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dynamic effect in the Capillary Pressure saturation relationship and its impacts on unsaturated flow
Vadose Zone Journal, 2002Co-Authors: Majid S Hassanizadeh, Michael A Celia, Helge K DahleAbstract:Capillary Pressure plays a central role in the description of water flow in unsaturated soils. While capillarity is ubiquitous in unsaturated analyses, the theoretical basis and practical implications of capillarity in soils remain poorly understood. In most traditional treatments of Capillary Pressure, it is defined as the difference between Pressures of phases, in this case air and water, and is assumed to be a function of saturation. Recent theories have indicated that Capillary Pressure should be given a more general thermodynamic definition, and its functional dependence should be generalized to include dynamic effects. Experimental evidence has slowly accumulated in the past decades to support a more general description of Capillary Pressure that includes dynamic effects. A review of these experiments shows that the coefficient arising in the theoretical analysis can be estimated from the reported data. The calculated values range from 10 4 to 10 7 kg (m s) −1 . In addition, recently developed pore-scale models that simulate interface dynamics within a network of pores can also be used to estimate the appropriate dynamic coefficients. Analyses of experiments reported in the literature, and of simulations based on pore-scale models, indicate a range of dynamic coefficients that spans about three orders of magnitude. To examine whether these coefficients have any practical effects on larger-scale problems, continuum-scale simulators may be constructed in which the dynamic effects are included. These simulators may then be run to determine the range of coefficients for which discernable effects occur. Results from such simulations indicate that measured values of dynamic coefficients are within one order of magnitude of those values that produce significant effects in field simulations. This indicates that dynamic effects may be important for some field situations, and numerical simulators for unsaturated flow should generally include the additional term(s) associated with dynamic Capillary Pressure.
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effects of heterogeneities on Capillary Pressure saturation relative permeability relationships
Journal of Contaminant Hydrology, 2002Co-Authors: Behzad Ataieashtiani, Majid S Hassanizadeh, Michael A CeliaAbstract:Abstract In theories of multiphase flow through porous media, Capillary Pressure–saturation and relative permeability–saturation curves are assumed to be intrinsic properties of the medium. Moreover, relative permeability is assumed to be a scalar property. However, numerous theoretical and experimental works have shown that these basic assumptions may not be valid. For example, relative permeability is known to be affected by the flow velocity (or Pressure gradient) at which the measurements are carried out. In this article, it is suggested that the nonuniqueness of Capillary Pressure–relative permeability–saturation relationships is due to the presence of microheterogeneities within a laboratory sample. In order to investigate this hypothesis, a large number of “numerical experiments” are carried out. A numerical multiphase flow model is used to simulate the procedures that are commonly used in the laboratory for the measurement of Capillary Pressure and relative permeability curves. The dimensions of the simulation domain are similar to those of a typical laboratory sample (a few centimeters in each direction). Various combinations of boundary conditions and soil heterogeneity are simulated and average Capillary Pressure, saturation, and relative permeability for the “soil sample” are obtained. It is found that the irreducible water saturation is a function of the Capillary number; the smaller the Capillary number, the larger the irreducible water saturation. Both drainage and imbibition Capillary Pressure curves are found to be strongly affected by heterogeneities and boundary conditions. Relative permeability is also found to be affected by the boundary conditions; this is especially true about the nonaqueous phase permeability. Our results reveal that there is much need for laboratory experiments aimed at investigating the interplay of boundary conditions and microheterogeneities and their effect on Capillary Pressure and relative permeability.
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modeling support of functional relationships between Capillary Pressure saturation interfacial area and common lines
Advances in Water Resources, 2001Co-Authors: Rudolf J Held, Michael A CeliaAbstract:Computational pore-scale network models describe two-phase porous media flow systems by resolving individual interfaces at the pore scale, and tracking these interfaces through the pore network. Coupled with volume averaging techniques, these models can reproduce relationships between measured variables like Capillary Pressure, saturation, and relative permeability. In addition, these models allow nontraditional porous media variables to be quantified, such as interfacial areas and common line lengths. They also allow explorations of possible relationships between these variables, as well as testing of new theoretical conjectures. Herein we compute relationships between Capillary Pressure, saturation, interfacial areas, and common line lengths using a pore-scale network model. We then consider a conjecture that definition of an extended constitutive relationship between Capillary Pressure, saturation, and interfacial area eliminates hysteresis between drainage and imbibition; such hysteresis is commonly seen in the traditional relationship between Capillary Pressure and saturation. For the sample pore network under consideration, we find that hysteresis can essentially be eliminated using a specific choice of displacement rules; these rules are within the range of experimental observations for interface displacements and therefore are considered to be physically plausible. We find that macroscopic measures of common line lengths behave similarly to fluid‐fluid interfacial areas, although the functional dependencies on Capillary Pressure and saturation diAer to some extent. ” 2001 Elsevier Science Ltd. All rights reserved.
Dorthe Wildenschild - One of the best experts on this subject based on the ideXlab platform.
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linking pore scale interfacial curvature to column scale Capillary Pressure
Advances in Water Resources, 2012Co-Authors: Ryan T Armstrong, Mark L Porter, Dorthe WildenschildAbstract:Synchrotron-based tomographic datasets of oil–water drainage and imbibition cycles have been analyzed to quantify phase saturations and interfacial curvature as well as connected and disconnected fluid configurations. This allows for close observation of the drainage and imbibition processes, assessment of equilibrium states, and studying the effects of fluid phase disconnection and reconnection on the resulting Capillary Pressures and interfacial curvatures. Based on this analysis estimates of Capillary Pressure calculated from interfacial curvature can be compared to Capillary Pressure measured externally with a transducer. Results show good agreement between curvature-based and transducer-based measurements when connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected fluid and the time allowed for equilibration. The favorable agreement between curvature-based and transducer-based Capillary Pressure measurements shows promise for the use of image-based estimates of Capillary Pressure for interfaces that cannot be probed with external transducers as well as opportunities for a detailed assessment of interfacial curvature during drainage and imbibition.
