scholarly journals Uncertainty quantification of RELAP5/MOD3.3 for interfacial shear stress during small break LOCA

2021 ◽  
Vol 7 (3) ◽  
pp. 1-7
Author(s):  
Hanh Tung DUONG ◽  
Hoang Anh NGUYEN ◽  
Richard TREWIN ◽  
Hiroshige KIKURA
Keyword(s):  
Shear Stress ◽  
Nuclear Power ◽  
System Analysis ◽  
Fluid Model ◽  
Interfacial Shear Stress ◽  
Reactor Core ◽  
Computer Code ◽  
Interfacial Shear ◽  
Two Phase ◽  
Two Fluid

The Best-Estimate Plus Uncertainty (BEPU) is applied as Deterministic Approach forsafety analysis of Nuclear Power Plant using the system analysis code. The system analysis code such as Relap5/Mod3.3 is required to be able to simulate the thermal-hydraulic behavior of nuclear reactor in some accident scenarios. Relap5/Mod3.3 is developed based on two-fluid models and 6 conservation equations for each phase which challenge for mathematical modeling such as onedemensional equation, time-dependent equation, multidimensional effects or complicated geometry. Thus, it is necessary to verify the applicability of a system analysis code that is able to predict accurately the two-phase flow such as interfacial shear stress between two phases: liquid and gases. It is also important to know the prediction uncertainty by using computer code due to the constitutive relation in the two-fluid model equation. In PWR’s Small-Break LOCA (SB-LOCA) accident, the loop-seal clearing is important phenomena where we would like to know how much water (reflux condensation) will be come into the reactor core from Steam Generator. In this work, the UPTFTRAM simulated the counter-current flow in Loop-seal Clearing between vapor and liquid in Loopseal during SB-LOCA is used to verify the applicability of Relap5/Mod3.3 and the experimental data are used to compare with simulation results. Moreover, the uncertainty evaluation or estimation is also investigated by applying the statistical method or BEPU in which the SUSA program developed by GRS is used.

Development of a Transient Mechanistic Two-Phase Flow Model for Wellbores

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 942-955 ◽  
Author(s):  
Mahdy Shirdel ◽  
Kamy Sepehrnoori
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Wall Shear ◽  
Two Fluid Model ◽  
Two Fluid

Summary A great deal of research has been focused on transient two-phase flow in wellbores. However, there is lack of a comprehensive two-fluid model in the literature. In this paper, we present an implementation of a pseudo-compositional, thermal, fully implicit, transient two-fluid model for two-phase flow in wellbores. In this model, we solve gas/liquid mass balance, gas/liquid momentum balance, and two-phase energy balance equations to obtain five primary variables: liquid velocity, gas velocity, pressure, holdup, and temperature. This simulator can be used as a stand-alone code or can be used in conjunction with a reservoir simulator to mimic wellbore/reservoir dynamic interactions. In our model, we consider stratified, bubbly, intermittent, and annular flow regimes using appropriate closure relations for interphase and wall-shear stress terms in the momentum equations. In our simulation, we found that the interphase and wall-shear stress terms for different flow regimes can significantly affect the model's results. In addition, the interphase momentum transfer terms mainly influence the holdup value. The outcome of this research leads to a more accurate simulation of multiphase flow in the wellbore and pipes, which can be applied to the surface facility design, well-performance optimization, and wellbore damage estimation.

Interfacial Shear in Two-Phase Wavy Flow in Closed Horizontal Channels

1974 ◽  
Vol 96 (2) ◽  
pp. 97-102 ◽  
Author(s):  
E. Kordyban
Keyword(s):  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Cross Section ◽  
Water Surface ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Channel Cross Section ◽  
Two Phase ◽  
The Waves

The interfacial shear stress for air flowing over a wavy water surface was determined experimentally in a closed horizontal channel by measuring the pressure drop and the structure of the water surface. The wall shear stress was measured with the aid of a Preston gauge. The range of tests included the conditions where the waves were large in comparison to the channel cross section. The equivalent sand roughness determined from the resistance formula for rough walls in fully turbulent flow was found to be related to the rms wave height through ks = 32Δh.

On the Implementation of Computational Methods for a Hyperbolic Two-Fluid Model

2012 ◽  
Author(s):  
Moon-Sun Chung ◽  
Youn-Gyu Jung ◽  
Sung-Jae Yi
Keyword(s):  
Numerical Method ◽  
Fluid Model ◽  
Computer Code ◽  
Equation System ◽  
Benchmark Problems ◽  
Surface Tension Effect ◽  
Two Phase ◽  
Complete Set ◽  
Two Fluid Model ◽  
Two Fluid

In this study, we focused on the implementation of numerical methods for a 2-fluid system including the surface tension effect in the momentum equations. This model consists of a complete set of 8 equations including 2-mass, 4-momentum, and 2-internal energy conservations having all real eigenvalues. Based on this equation system with upwind numerical method, we first make a pilot 2-dimensional computer code and then solve some benchmark problems in order to check whether this model and numerical method is able to properly analyze some fundamental two-phase flow systems or not.

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