Evaluation of Computational Fluid Dynamics Code CFX byNumerical Simulations of Fundamental and Rod Bundle Flows

SUMMARY

1. Project Title

Evaluation of Computational Fluid Dynamics Code CFX by Numerical Simulations of

Fundamental and Rod Bundle Rows

2. Objective and Importance of the Project

This study performed the numerical analyses of the fundamental flow problems and the

rod bundle flow problems to evaluate the CFX code. The numerical analyses were

useful to understand the turbulent structure of the rod bundle flow as well as the

characteristics of CFX. The result of this study is therefore expected to provide a guide

for the numerical simulation of the complex flow in rod bundle with grid spacer, on

which the flow mixing devices (CHF promoters) are attached.

3. Scope and Contents of the Project

Four fundamental flow problems and two flow problems in rod bundles were selected

to examine the effects of computational grid, numerical scheme, flow model and

boundary conditions. The lengths of flow separation and reattchment in the backward

facing step flow were compared for the various Reynolds numbers. The generation and

decay of vortex were also examined for the uniform flow past a circular cylinder and a

square cylinder. The characteristics in pipe turbulent flow were investigated depending

on the computational grid and the turbulence model. The CFX predictions of the

turbulent flows in 3x3 rod bundle and hi four rodded wall channel were compared with

their experimental results.

4. Results and Proposal for Application

This study enhanced the understanding of the CFX code and investigated the

sensitivities of the computational grid, the numerical scheme and the turbulence model.

Since the CFD analysis of the turbulent flow in rod bundle takes less time and cost than

the experimental approach, the CFX application is very useful to optimize the designs

of a nuclear fuel spacer and a flow mixing device.

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BIBLIOGRAPHIC INFORMATION SHEET

Performing Org.

Report No.

Sponsoring Org.

Report No.

Standard

Report No.INIS Subject Code

KAERI/TR-1182/98

Title / Subtitle

Evaluation of Computational Fluid Dynamics Code CFX by

Numerical Simulations of Fundamental and Rod Bundle FlowsProject Manager

and DepartmentIn Wang Kee (Fuel Design Technology Development)

Researcher and

Department

Oh Dong Seok (Fuel Design Technology Development)Chun Tae Hyun (Fuel Design Technology Development)

PublicationPlace

Taejon Publisher KAERIPublication

Date1998

Page 30 p. 111. & Tab. Yes( o ), No ( ) Size19x26 Cm.

Note

Classified Open( o ), Restricted(. Class Document

Report Type TR

Sponsoring Org. Contract No.

Abstract (15-20 Lines)

Four fundamental flow problems and two flow problems in rod bundles were selected toexamine the effects of computational grid, numerical scheme, flow model and boundaryconditions. The lengths of flow • separation and reattchment in the backward facing ; stepflow were compared for the various Reynolds numbers. The generation and decay ofvortex were also examined for the uniform flow past a circular cylinder and a squarecylinder. The characteristics in pipe turbulent flow were investigated depending on thecomputational grid and the turbulence model. The CFX predictions of the turbulent flowsin 3x3 rod bundle and in four rodded wall channel were compared with theirexperimental results.

Subject Keywords(About 10 words)

Computational Fluid Dynamics, CFX, Computational Grid,

Numerical Scheme, Turbulence Model