The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
C J Van Duijn - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Dynamic Capillarity in Modeling Saturation Overshoot during Infiltration
Soil Science Society of America, 2019Co-Authors: Luwen Zhuang, C J Van Duijn, Majid S. HassanizadehAbstract:Gravity-driven fingering has been observed during downward infiltration of water into dry sand. Moreover, the water saturation profile within each finger is non-monotonic, with a saturation overshoot at the finger tip. As reported in the literature, these effects can be simulated by an extended form of the Richards equation, where a dynamic Capillarity term is included. The coefficient of proportionality is called the dynamic Capillarity coefficient. The dynamic Capillarity coefficient may depend on saturation. However, there is no consensus on the form of this dependence. We provide a detailed traveling wave analysis of four distinctly different functional forms of the dynamic Capillarity coefficient. In some forms, the coefficient increases with increasing saturation, and in some forms, it decreases. For each form, we have found an explicit expression for the maximum value of saturation in the overshoot region. In current formulations of dynamic Capillarity, if the value of the Capillarity coefficient is large, the value of saturation in the overshoot region may exceed unity, which is obviously nonphysical. So, we have been able to ensure boundedness of saturation regardless of the value of the dynamic Capillarity coefficient by extending the capillary pressure–saturation relationship. Finally, we provide a qualitative comparison of the results of traveling wave analysis with experimental observations
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travelling wave solutions for the richards equation incorporating non equilibrium effects in the Capillarity pressure
Nonlinear Analysis-real World Applications, 2018Co-Authors: C J Van Duijn, K Mitra, I S PopAbstract:The Richards equation is a mathematical model for unsaturated flow through porous media. This paper considers an extension of the Richards equation, where non-equilibrium effects like hysteresis and dynamic Capillarity are incorporated in the relationship that relates the water pressure and the saturation. The focus is on travelling wave solutions, for which the existence is investigated first for the model including hysteresis and subsequently for the model including dynamic Capillarity effects. In particular, such solutions may have non monotonic profiles, which are ruled out when considering standard, equilibrium type models, but have been observed experimentally. The paper ends with numerical experiments confirming the theoretical results.
Majid S. Hassanizadeh - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Dynamic Capillarity in Modeling Saturation Overshoot during Infiltration
Soil Science Society of America, 2019Co-Authors: Luwen Zhuang, C J Van Duijn, Majid S. HassanizadehAbstract:Gravity-driven fingering has been observed during downward infiltration of water into dry sand. Moreover, the water saturation profile within each finger is non-monotonic, with a saturation overshoot at the finger tip. As reported in the literature, these effects can be simulated by an extended form of the Richards equation, where a dynamic Capillarity term is included. The coefficient of proportionality is called the dynamic Capillarity coefficient. The dynamic Capillarity coefficient may depend on saturation. However, there is no consensus on the form of this dependence. We provide a detailed traveling wave analysis of four distinctly different functional forms of the dynamic Capillarity coefficient. In some forms, the coefficient increases with increasing saturation, and in some forms, it decreases. For each form, we have found an explicit expression for the maximum value of saturation in the overshoot region. In current formulations of dynamic Capillarity, if the value of the Capillarity coefficient is large, the value of saturation in the overshoot region may exceed unity, which is obviously nonphysical. So, we have been able to ensure boundedness of saturation regardless of the value of the dynamic Capillarity coefficient by extending the capillary pressure–saturation relationship. Finally, we provide a qualitative comparison of the results of traveling wave analysis with experimental observations
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effect of fluids properties on non equilibrium Capillarity effects dynamic pore network modeling
International Journal of Multiphase Flow, 2011Co-Authors: Vahid Joekarniasar, Majid S. HassanizadehAbstract:We have developed a Dynamic Pore-network model for Simulating Two-phase flow in porous media (DYPOSIT). The model is applicable to both drainage and imbibition processes. Employing improved numerical and geometrical features in the model facilitate a physically-based pore-scale simulator. This computational tool is employed to perform several numerical experiments (primary and main drainage, main imbibition) to investigate the current Capillarity theory. Traditional two-phase flow formulations state that the pressure difference between the two phase is equal to the capillary pressure, which is assumed to be a function of saturation only. Many theoretical and experimental studies have shown that this assumption is invalid and the pressure difference between the two fluids is not only equal to the capillary pressure but is also related to the variation of saturation with time in the domain; this is referred to as the non-equilibrium Capillarity effect. To date, non-equilibrium Capillarity effect has been investigated mainly under drainage. In this study, we analyze the non-equilibrium Capillarity theory under drainage and imbibition as a function of saturation, viscosity ratio, and effective viscosity. Other aspects of the dynamics of two-phase flow such as trapping and saturation profile are also studied.
Robert Finn - One of the best experts on this subject based on the ideXlab platform.
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on the Capillarity equation in two dimensions
Journal of Mathematical Fluid Mechanics, 2016Co-Authors: Rajat Bhatnagar, Robert FinnAbstract:We study the Capillarity equation from the global point of view of behavior of its solutions without explicit regard to boundary conditions. We show its solutions to be constrained in ways, that have till now not been characterized in literature known to us.
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on the capillary problem for compressible fluids
Journal of Mathematical Fluid Mechanics, 2007Co-Authors: Robert Finn, Garving K LuliAbstract:Classical Capillarity theory is based on a hypothesis that virtual motions of fluid particles distinct from those on a surface interface have no effect on the form of the interface. That hypothesis cannot be supported for a compressible fluid. A heuristic reasoning suggests that even small amounts of compressibility could have significant effect on surface behavior. In an earlier work, Finn took a partial account of compressibility, and formulated a variant of the classical Capillarity equation for fluid surface height in a vertical capillary tube; he was led to a necessary condition for existence of a solution with prescribed mass in a tube closed at the bottom. For a circular tube, he proved that the condition also suffices, and that solutions are uniquely determined for any contact angle γ.
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the contact angle in Capillarity
Physics of Fluids, 2006Co-Authors: Robert FinnAbstract:In 1805, Thomas Young gave a reasoning to support the view that the contact angle at a solid/liquid/gas interface is a physical constant depending only on the materials, and in no other way on the particular configuration considered. That conclusion has become one of the underpinnings of both classical and modern Capillarity theory. The present paper raises some questions about the reasoning and some of its consequences, and offers partial answers.
I S Pop - One of the best experts on this subject based on the ideXlab platform.
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travelling wave solutions for the richards equation incorporating non equilibrium effects in the Capillarity pressure
Nonlinear Analysis-real World Applications, 2018Co-Authors: C J Van Duijn, K Mitra, I S PopAbstract:The Richards equation is a mathematical model for unsaturated flow through porous media. This paper considers an extension of the Richards equation, where non-equilibrium effects like hysteresis and dynamic Capillarity are incorporated in the relationship that relates the water pressure and the saturation. The focus is on travelling wave solutions, for which the existence is investigated first for the model including hysteresis and subsequently for the model including dynamic Capillarity effects. In particular, such solutions may have non monotonic profiles, which are ruled out when considering standard, equilibrium type models, but have been observed experimentally. The paper ends with numerical experiments confirming the theoretical results.
Joel D. Kopple - One of the best experts on this subject based on the ideXlab platform.
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effect of endurance and or strength training on muscle fiber size oxidative capacity and Capillarity in hemodialysis patients
Journal of Applied Physiology, 2015Co-Authors: Michael I. Lewis, Richard Casaburi, Joel D. Kopple, Huiyua Wang, Thomas W Store, Mario FournieAbstract:We previously reported reduced limb muscle fiber succinate dehydrogenase (SDH) activity and Capillarity density and increased cross-sectional areas (CSAs) of all fiber types in maintenance hemodial...
