scholarly journals Two-phase Flow Analyses Using Interface Tracking and the Visualization

2001 ◽  
Vol 21 (80) ◽  
pp. 8-13_1
Author(s):  
Tomoaki KUNUGI
Keyword(s):  
Two Phase Flow ◽  
Interface Tracking ◽  
Phase Flow ◽  
Two Phase

Numerical Evaluation of Fluid Mixing Phenomena in Boiling Water Reactor Using Advanced Interface-Tracking Method

2007 ◽  
Author(s):  
Hiroyuki Yoshida ◽  
Takuji Nagayoshi ◽  
Kazuyuki Takase ◽  
Hajime Akimoto
Keyword(s):  
Two Phase Flow ◽  
Flow Simulation ◽  
Fluid Mixing ◽  
Interface Tracking ◽  
Phase Flow ◽  
Two Phase ◽  
Tracking Method ◽  
Water Reactor ◽  
Hydraulic Design ◽  
Actual Size

Thermal-hydraulic design of the current boiling water reactor (BWR) is performed by correlations with empirical results of actual-size tests. Then, for the Innovative Water Reactor for Flexible Fuel Cycle (FLWR) core, an actual size test that simulates its design is required to confirm or modify the correlations. Development of a method that enables the thermal-hydraulic design of nuclear rectors without these actual size tests is desired, because these tests take a long time and entail great cost. For this reason we developed an advanced thermal-hydraulic design method for FLWRs using innovative two-phase flow simulation technology. In this study, detailed two-phase flow simulation code using advanced interface tracking method: TPFIT is developed to get the detailed information of the two-phase flow. In this paper, firstly, we tried to verify the TPFIT code comparing with the existing 2-channel air-water mixing experimental results. Secondary, the TPFIT code was applied to simulation of steamwater two-phase flow in modeled two subchannels of current BWRs rod bundle. The fluid mixing was observed at a gap between the subchannels. The existing two-phase flow correlation for fluid mixing is evaluated using detailed numerical simulation data. From the data, pressure difference between fluid channels is responsible for the fluid mixing, and effects of the time averaged and fluctuating pressure difference must be incorporated in the two-phase flow correlation for fluid mixing.

Development of Advanced Two-Fluid Model for Boiling Two-Phase Flow in Rod Bundles

2010 ◽  
Author(s):  
Hiroyuki Yoshida ◽  
Hideaki Hosoi ◽  
Takayuki Suzuki ◽  
Kazuyuki Takase
Keyword(s):  
Constitutive Equations ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interface Tracking ◽  
Phase Flow ◽  
Rod Bundles ◽  
Two Phase ◽  
Tracking Method ◽  
Two Fluid Model ◽  
Two Fluid

Two-fluid model can simulate two-phase flow by computational cost less than detailed two-phase flow simulation method such as interface tracking method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as rod bundles in nuclear reactors. However, two-fluid model include a lot of constitutive equations. Then, applicability of these constitutive equations must be verified by use of experimental results, and the two-fluid model has problems that the results of analyses depend on accuracy of constitutive equations. To solve these problems, we have been developing an advanced two-fluid model. In this model, an interface tracking method is combined with the two-fluid model to predict large interface structure behavior accurately. Interfacial structures larger than a computational cells, such as large droplets and bubbles, are calculated using the interface tracking method. And droplets and bubbles that are smaller than cells are simulated by the two-fluid model. Constitutive equations to evaluate the effects of small bubbles or droplets on two-phase flow are required in the advanced two-fluid model as same as a conventional two-fluid model. However, dependency of small bubbles and droplets on two-phase flow characteristic is relatively small, and the experimental results to verify the equations are not required much. In this study, we modified the advanced two-fluid model to improve the stability of the numerical simulation and reduce the computational time. Moreover, the modified model was incorporated to the 3-dimensional two-fluid model code ACE-3D. In this paper, we describe the outline of this model and the modification performed in this study. Moreover, the numerical results of two-phase flow in various flow conditions.

Bubble flow simulations using the intersection marker (ISM) interface tracking method

2018 ◽  
Vol 28 (1) ◽  
pp. 118-137 ◽  
Author(s):  
Mark Ho ◽  
Guan Heng Yeoh ◽  
John Arthur Reizes ◽  
Victoria Timchenko
Keyword(s):  
Surface Tension ◽  
Two Phase Flow ◽  
Front Tracking ◽  
Interface Tracking ◽  
Phase Flow ◽  
Cfd Simulations ◽  
Two Phase ◽  
Content Type ◽  
Tracking Method ◽  
Flow Simulations

Purpose Interface distinct two-phase computational fluid dynamics (CFD) simulations require accurate tracking in surface curvature, surface area and volume fraction data to precisely calculate effects such as surface tension, interphase momentum and interphase heat and mass transfer exchanges. To attain a higher level of accuracy in two-phase flow CFD simulations, the intersection marker (ISM) method was developed. The ISM method has cell-by-cell remeshing capability that is volume conservative, maintains surface continuity and is suited for the tracking of interface deformation in transient two-phase flow simulations. Studies of isothermal single bubbles rising in quiescent water were carried out to test the ISM method for two-phase flow simulations. Design/methodology/approach The ISM method is a hybrid Lagrangian–Eulerian front tracking algorithm which can model an arbitrary three-dimensional surface within an array of cubic control volumes. Fortran95 was used to implement the ISM method, which resulted in approximately 25,000+ lines of written code and comments. To demonstrate the feasibility of the ISM algorithm for two-phase flow simulations, the ISM algorithm was coupled with an in-house CFD code, which was modified to simulate two-phase flows using a single fluid formulation. The constitutional equations incorporated terms of variable density and viscosity. In addition, body force source terms were included in the momentum equation to account for surface tension and buoyancy effects. Findings The performance of two-phase flow simulations was benchmarked against experimental data for four air/water bubbles with 1, 2.5, 5 and 10 mm of diameter rising in quiescent fluid. A variety of bubble sizes were tested to demonstrate the accuracy of the ISM interface tracking method. The results attained were in close agreement with experimental observations. Practical implications The results obtained show that the ISM method is a viable means for interface tracking of two-phase flow CFD simulations. Other applications of the ISM method include simulations of solid–fluid interaction and other immersed boundary flow problems. Originality/value The ISM method is a novel approach to front tracking, and the results shown are original in content.

Interface Tracking Simulations of Two-Phase Flow Utilizing Adaptive Meshing Capabilities

2018 ◽  
Author(s):  
Joseph J. Cambareri ◽  
Igor A. Bolotnov
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Model Development ◽  
Numerical Data ◽  
Mesh Adaptation ◽  
Interface Tracking ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Simulations ◽  
Full Resolution

Due to the increase of computing efficiency and power, full-resolution two-phase flow simulations have become a practical research tool for model development and analysis of reactor flows. The expansion of state-of-the-art high performance computing (HPC) facilities allows for the use of direct numerical simulation (DNS) coupled with Interface Tracking Methods (ITM) to perform full resolution simulations. Given adequate spatial and temporal resolution, DNS can resolve all relevant turbulent scales, allowing for the extraction of high quality and detailed turbulent and two-phase flow numerical data for use in model development. While larger scale bubbly flow DNS are becoming ever more affordable, it is still computationally expensive due to the requirements of the spatial discretization. This presents the largest obstacle for future applications of DNS. For this reason, mesh adaptation techniques are sought after to reduce the computational expense of bubbly flow simulations in complex geometries. By fully resolving only the areas of specific interest, the computational costs of DNS can be reduced. Grid refinement can be based on the location of the interface between the two phases, area of greatest turbulent intensity, averaged bulk fluid velocity data, or the prediction of bubble movement. Coupled with an advanced bubble tracking algorithm, the path of individual bubbles moving through the computational domain can be predicted, and the computational mesh refined within the path area. This refinement can create tracks of greater resolution for the bubbles to move through in the domain, while keeping the bulk resolution of the mesh coarser. Through these means, the overall cost of the simulation is reduced, while high quality numerical data is still obtainable. This work outlines the enhancement of existing mesh adaptation algorithms to implement the bubble tracking refinement, and its practical applications to full resolution two-phase flow simulations.

101 Numerical Prediction of Two-Phase Flow Behavior under Seismic Condition by use of Interface Tracking Method

2012 ◽  
Vol 2012.25 (0) ◽  
pp. 693-695
Author(s):  
Hiroyuki Yoshida ◽  
Taku Nagatake ◽  
Kazuyuki Takase ◽  
Akiko Kaneko ◽  
Hideaki Monji ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Flow Behavior ◽  
Numerical Prediction ◽  
Interface Tracking ◽  
Phase Flow ◽  
Two Phase ◽  
Tracking Method
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