Development of One-Group and Two-Group Interfacial Area Transport Equation

Ishii, Mamoru; Kim, S.

doi:10.13182/nse01-69

Cited by 101 publications

(53 citation statements)

References 17 publications

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“…This term is quite important in interfacial area transport. Therefore, the constitutive equations of this term are given by Ishii (2000a, 2000b) and Ishii and Kim (2004) based on detailed mechanistic modeling. The second term in right hand side of Eq.…”

Section: Interfacementioning

confidence: 99%

“…Therefore, the establishment of the measurement method of local interfacial area concentration was strongly required. Ishii (1975) and Delhaye (1968) derived following relation among time averaged interfacial area concentration, number of interfaces and velocity of interface. They pointed out local interfacial area concentration can be measured using two or three sensor probe based on this relation.…”

Section: Experimental Researches On Interfacial Area Concentrationmentioning

confidence: 99%

“…In order to analyze two-phase flow phenomena, various models such as homogeneous model, slip model, drift flux model and two-fluid model have been proposed. Among these models, the two-fluid model (Ishii (1975), Delhaye (1968)) is considered the most accurate model because this model treats each phase separately considering the phase interactions at gas-liquid interfaces. Therefore, nowadays, two-fluid model is widely adopted in many best estimate codes of nuclear reactor safety.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transport of Interfacial Area Concentration in Two-Phase Flow

Kataoka¹,

Yoshida²,

Naitoh³

et al. 2012

Nuclear Reactors

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Section: Interfacementioning

confidence: 99%

Section: Experimental Researches On Interfacial Area Concentrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transport of Interfacial Area Concentration in Two-Phase Flow

Kataoka¹,

Yoshida²,

Naitoh³

et al. 2012

Nuclear Reactors

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“…(18) represent the source and sink terms due to bubble coalescence and break up and phase change. The constitutive equations are given by Ishii (2000a, 2000b) and Ishii and Kim (2004) based on detailed mechanistic modeling. Equation (18) is practical transport equation of interfacial area concentration although its applicability is limited to dispersed flow (bubbly flow and droplet flow).…”

Section: Local Instant Formulation Of Interfacial Area Concentratmentioning

confidence: 99%

Modeling of turbulent transport term of interfacial area concentration in gas–liquid two-phase flow

Kataoka

Yoshida

Naitoh

et al. 2012

Nuclear Engineering and Design

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A new and rigorous modeling of basic transport equation and constitutive equations of turbulent transport terms of interfacial area concentration was carried out.Based on these local instant formulation, basic transport equation of interfacial area concentration was rigorously formulated in term of spatial correlation functions of characteristic function (local instant volume fraction) and its directional derivative of each phase. In the basic transport equations, interfacial area concentration is transported by averaged interfacial velocityIn the previous models, interfacial velocity is roughly approximated by velocity of each phase.In the present model, interfacial velocity is rigorously formulated in term of spatial correlation functions of characteristic function and velocity of each phase and their directional derivatives. In this new formulation, the averaged interfacial velocity was shown to be correlation functions of fluctuation of velocity and local instant void fraction and their derivatives which reflect the transport of interfacial area concentration due to interaction between interfacial area and turbulence of each phase. Basic conservation equations of spatial correlation functions of characteristic function and velocity of each phase were also derived based on the conservation equations momentum and its fluctuation of each phase. For practical purpose, further modeling of this turbulent transport terms of interfacial area concentration was carried out. As a result, constitutive equations of turbulent diffusion and lateral migration of interfacial area concentration were obtained which can be applied to various flow regime of two-phase flow. I. IntroductionThe two-phase flow phenomenon is playing an important role about safety issues of a nuclear reactor. In order to analyze two-phase flow phenomena, various models such as homogeneous model, slip model, drift flux model and two-fluid model have been proposed. Among these models, the two-fluid model (Ishii (1975), Delhaye (1968) is considered the most accurate model because this model treats each phase separately considering the phase interactions at gas-liquid interfaces.More realistic evaluation is attainable especially by taking a multi-dimensional effect into consideration appropriately. That is, it is desirable that many nuclear reactor safety problems are solved by using the two-phase CFD tools, which simulate the complex two-phase flows with a finer space and time resolution than that used in the present two-fluid model codes such as RELAP, TRAC, CATHARE, and ATHLET. There are, however, the following two difficulties to be resolved.(1) The CPU time drastically increases as the grid becomes fine.(2) There is no reliable and accurate modeling of the interfacial area for a finer mesh. The JNES have started the plan shown in Table 1 to prepare the two-phase CFD tool.

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“…For example, in the derivation of vertically integrated shallow water flow equations, a kinematic condition on the top surface is imposed based on the condition that no fluid crosses that surface (Vreugdenhil, 1995). Macroscale kinematic equations for interfaces between fluids in the absence of porous media have been proposed in the context of boiling (Kocamustafaogullari and Ishii, 1995;Ishii et al, 2005). Despite the fact that interface reconfiguration has an important role in determining the properties and behavior of a multi-fluid porous medium system, attention to this feature is extremely limited (Gray and Miller, 2013;Gray et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

On the consistency of scale among experiments, theory, and simulation

McClure

Dye

Miller

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. As a tool for addressing problems of scale, we consider an evolving approach known as the thermodynamically constrained averaging theory (TCAT), which has broad applicability to hydrology. We consider the case of modeling of two-fluid-phase flow in porous media, and we focus on issues of scale as they relate to various measures of pressure, capillary pressure, and state equations needed to produce solvable models. We apply TCAT to perform physicsbased data assimilation to understand how the internal behavior influences the macroscale state of two-fluid porous medium systems. A microfluidic experimental method and a lattice Boltzmann simulation method are used to examine a key deficiency associated with standard approaches. In a hydrologic process such as evaporation, the water content will ultimately be reduced below the irreducible wetting-phase saturation determined from experiments. This is problematic since the derived closure relationships cannot predict the associated capillary pressures for these states. We demonstrate that the irreducible wetting-phase saturation is an artifact of the experimental design, caused by the fact that the boundary pressure difference does not approximate the true capillary pressure. Using averaging methods, we compute the true capillary pressure for fluid configurations at and below the irreducible wetting-phase saturation. Results of our analysis include a state function for the capillary pressure expressed as a function of fluid saturation and interfacial area.

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Development of One-Group and Two-Group Interfacial Area Transport Equation

Cited by 101 publications

References 17 publications

Transport of Interfacial Area Concentration in Two-Phase Flow

Transport of Interfacial Area Concentration in Two-Phase Flow

Modeling of turbulent transport term of interfacial area concentration in gas–liquid two-phase flow

On the consistency of scale among experiments, theory, and simulation

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