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Research Papers

Enhancing Numerical Stability of a Two-Fluid Model by the Use of Interfacial Pressure Terms

[+] Author and Article Information
Tomio Okawa

Professor
Department of Mechanical Engineering and Intelligent Systems,
The University of Electro-Communications,
1-5-1, Chofugaoka, Chofu-shi,
Tokyo 182-8585, Japan
e-mail: okawa.tomio@uec.ac.jp

1Corresponding author.

Manuscript received August 18, 2014; final manuscript received December 6, 2014; published online March 24, 2015. Assoc. Editor: Mark Anderson.

ASME J of Nuclear Rad Sci 1(2), 021001 (Mar 24, 2015) (11 pages) Paper No: NERS-14-1036; doi: 10.1115/1.4029415 History: Received August 18, 2014; Accepted December 17, 2014; Online March 24, 2015

Analytical and numerical investigations were carried out to show that the characteristics and the numerical stability of the two-fluid model are improved by the use of the interfacial pressure terms that express the pressure difference between bubbles and continuous liquid phase in bubbly two-phase flow. In particular, it was demonstrated that the numerical stability is enhanced not only in the simulation of adiabatic two-phase flow but also in the simulation of subcooled flow boiling.

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References

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Figures

Grahic Jump Location
Fig. 1.

Calculation results of steam-water two-phase flow in a uniformly heated vertical round tube for three sets of constitutive models (Dh=9.124  mm, L=2  m, qW=35  kW/m2, VIN=0.5  m/s, ΔTSUB,IN=0  K, pOUT=0.1  MPa, Δx=0.2  m, Δt=0.1  s): (a) TRAC-PF1, (b) RELAP5/MOD2, and (c) TRAC-BF1.

Grahic Jump Location
Fig. 2

Time variations of the inlet pressure and void fractions when IPTs are not included: (a) NCELL=20, (b) NCELL=200, (c) NCELL=500, and (d) NCELL=1000

Grahic Jump Location
Fig. 3

Time variations of the inlet pressure and void fractions when IPTs are included (standard version; NCELL=1000): (a) Cp=0.25 and (b) Cp=0.5

Grahic Jump Location
Fig. 4

Time variations of the inlet pressure and void fractions when IPTs are included (simple version; NCELL=1000): (a) Cp=0.25 and (b) Cp=0.5

Grahic Jump Location
Fig. 5

Time variations of the inlet pressure and void fraction when the relative velocity is set to zero at the inlet (NCELL=500): (a) No IPTs, (b) Standard (Cp=0.25), and (c) Simple (Cp=0.25)

Grahic Jump Location
Fig. 6

Axial distributions of main variables in the steady state when the heating power is kept at p in the analysis of subcooled flow boiling (No IPTs; NCELL=100)

Grahic Jump Location
Fig. 7

Time variations of the void fractions, the velocities of gas and liquid phases, and the inlet pressure when IPTs are not included in the analysis of subcooled flow boiling: (a) NCELL=100, (b) NCELL=200, (c) NCELL=500, and (d) NCELL=1000

Grahic Jump Location
Fig. 8

Numerical solutions of subcooled flow boiling when IPTs are included (standard version): (a) NCELL=200, Cp=0.25; (b) NCELL=500, Cp=0.25; and (c) NCELL=500, Cp=0.5

Grahic Jump Location
Fig. 9

Numerical solutions of subcooled flow boiling when IPTs are included (simplified version): (a) NCELL=200, Cp=0.25; (b) NCELL=500, Cp=0.25; and (c) NCELL=500, Cp=0.5

Grahic Jump Location
Fig. 10

Numerical solutions of subcooled flow boiling when IPTs are included (simplified version; NCELL=1000): (a) Cp=0.25, (b) Cp=0.5, and (c) Cp=1

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