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Modelling of transport processes in concrete at elevated temperatures -an alternative formulation for sorption isotherms
Published in Günther Meschke, René de Borst, Herbert Mang, Nenad Bićanić, Computational Modelling of Concrete Structures, 2020
C.J. Pearce, K. Kukla, N. Bićanić, C.T. Davie
At a microscopic level, when gas and liquid phases meet, there is a discontinuity in pressure across the interface. This pressure difference is the capillary pressure. The magnitude of the capillary pressure in a particular pore depends on the surface tension and the curvature of the interface. In a homogenized continuum representing a medium with a complex and irregular void space, the macroscopic capillary pressure, PC, must be determined as a statistical average of the microscopic capillary pressure (see, for example, Bear (1972)). Furthermore, the macroscopic capillary pressure is most conveniently expressed as a function of the degree of saturation, S and often referred to as a water retention curve or capillary pressure curve. PC=PC(S)
4 for a backfilled salt rock repository
Published in Manfred Wallner, Karl-Heinz Lux, Wolfgang Minkley, H. Reginald Hardy, The Mechanical Behavior of Salt – Understanding of THMC Processes in Salt, 2017
As discussed in previous sections, the exsolution of the gas is strictly dependent on the thermodynamical and chemical equilibrium state of the CO2-brine-solid phases. Once the free gas phase is appeared, the two-phase flow dominates the transport. This is controlled by the relative permeability concept and capillary forces. The mobility of the gas phase is higher than the liquid phase thus it is expected that gas overrides the liquid phase tending to migrate vertically to the top of the geologic structure. Modelling of two-phase flow in porous media requires the specification of the functional relationship between capillary pressure, relative permeability and saturation. Together capillary pressure, relative permeability control the way the liquid, brine (wetting phase) and gas, e.g. CO2 (non-wetting) phases interact.
Hydromechanical properties of sedimentary rock under injection of supercritical carbon dioxide
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
A. Arsyad, Y. Mitani, T. Babadagli
The capillary pressure of the specimens was measured through mercury injection tests. The interfacial tension (IFT) for air-mercury was found to be 485 mN/m but this data must be converted to water-CO2 capillary pressure data. The IFT of CO2-water at the experimental condition was taken as 32.1 mN/m (Chiquet et al., 2007). As shown in Figure 10, the capillary pressure of Ainoura 1 is higher than that of Ainoura 2. In order to determine irreducible water saturation (Swr), the threshold capillary pressure of the specimens (P0), and shape parameter (m), the capillary pressure data was matched to the capillary pressure computed using Van Genuchten equation (1980). The three parameters (Swr, Po, m) for Ainoura 1 and Ainoura 2 specimens were obtained as 0.45, 25 kPa, 0.61, and 0.45, 750 kPa, 0.68, respectively.
Influences of reservoir water level drawdown on slope stability and reliability analysis
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2019
Xuecheng Gao, Hanlong Liu, Wengang Zhang, Wei Wang, Zhenyu Wang
Only the PWP is considered in the single-phase flow mode with neglect of the capillary pressure. Therefore, the pore pressures are zero above the phreatic surface while single-phase flow analysis is conducted. In the two-phase flow mode, the voids are completely filled by two immiscible fluids of water and air. The capillary pressure , as a function of saturation degree , is defined as the pressure difference of non-wetting fluid (air) and wetting fluid (water). Flow of both fluids follows Darcy’s law, and the effective permeability is given as a fraction of that in single-fluid mode. In FLAC, the relationship between capillary pressure and relative permeability is built-in the empirical laws of the van Genuchten form (Van Genuchten 1980). More details of the concepts involved in the mathematical description of multiphase flow may be found in Peaceman (1977).
Comparative study of capillary rise characteristics of saltwater in loose materials
Published in Marine Georesources & Geotechnology, 2022
Nguyen Ngoc Truc, Nguyen Van Hoang
In modelling carbon dioxide retention in heterogeneous strata, Plug and Bruining (2007) proposed a continuous measure of capillary pressure. The capillary pressure was also investigated by comparative modelling of heterogeneous materials and homogeneous material. Factors influencing capillary pressure should be considered, such as flow rate, direction, viscosity of the liquid, and spatial scale of heterogeneous media (Dale et al. 1997). William, Bruning, and Miller (2019) significantly improved the capillary pressure state equation and confirmed that the capillary pressure in loose materials can be demonstrated by a non-hysteretic function.
High-Fidelity Modeling and Experiments to Inform Safety Analysis Codes for Heat Pipe Microreactors
Published in Nuclear Technology, 2023
Carolina da Silva Bourdot Dutra, Elia Merzari, John Acierno, Adam Kraus, Annalisa Manera, Victor Petrov, Taehwan Ahn, Pei-Hsun Huang, Dillon Shaver
In order to increase the maximum heat transfer at which a heat pipe can operate, the design of the wick must be considered. For example, porosity, permeability, and liquid gap size changes can affect the maximum attainable capillary pressure.51 This part of the work aims to validate the Sockeye simulations of a heat pipe model against the experiments discussed in Sec. II. We also compare numerically evaluated capillary limit curves for the same model against available capillary limit curves provided in the literature.