# CFD study of natural convection mixing in a steam generator mock-up: Comparison between full geometry and porous media approaches

## Abstract

In CFD simulations of flow mixing in a steam generator (SG) during natural circulation, one is faced with the problem of representing the thousands of SG U-tubes. Typically simplifications are made to render the problem computationally tractable. In particular, one or a number of tubes are lumped in one volume which is treated as a single porous medium. This approach dramatically reduces the computational size of the problem and hence simulation time. In this work, we endeavor to investigate the adequacy of this approach by performing two separate simulations of flow in a mock-up with 262 U-tubes, i.e. one in which the porous media model is used for the tube bundle, and another in which the full geometry is represented. In both simulations, the Reynolds Stress (RMS) model of turbulence is used. We show that in steady state conditions, the porous media treatment yields results which are comparable to those of the full geometry representation (temperature distribution, recirculation ratio, hot plume spread, etc). Hence, the porous media approach can be extended with a good degree of confidence to the full scale SG. (authors)

- Authors:

- Paul Scherrer Institut, 5234 Villigen (Switzerland)

- Publication Date:

- Research Org.:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)

- OSTI Identifier:
- 22107844

- Resource Type:
- Conference

- Resource Relation:
- Conference: ICAPP '12: 2012 International Congress on Advances in Nuclear Power Plants, Chicago, IL (United States), 24-28 Jun 2012; Other Information: Country of input: France; 13 refs.; Related Information: In: Proceedings of the 2012 International Congress on Advances in Nuclear Power Plants - ICAPP '12| 2799 p.

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 42 ENGINEERING; 22 GENERAL STUDIES OF NUCLEAR REACTORS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; FLOW STRESS; FLUID MECHANICS; GEOMETRY; MOCKUP; NATURAL CONVECTION; NUCLEAR POWER PLANTS; POROUS MATERIALS; REYNOLDS NUMBER; STEADY-STATE CONDITIONS; STEAM GENERATORS; TEMPERATURE DISTRIBUTION; TUBES; TURBULENCE

### Citation Formats

```
Dehbi, A., and Badreddine, H.
```*CFD study of natural convection mixing in a steam generator mock-up: Comparison between full geometry and porous media approaches*. United States: N. p., 2012.
Web.

```
Dehbi, A., & Badreddine, H.
```*CFD study of natural convection mixing in a steam generator mock-up: Comparison between full geometry and porous media approaches*. United States.

```
Dehbi, A., and Badreddine, H. Sun .
"CFD study of natural convection mixing in a steam generator mock-up: Comparison between full geometry and porous media approaches". United States.
```

```
@article{osti_22107844,
```

title = {CFD study of natural convection mixing in a steam generator mock-up: Comparison between full geometry and porous media approaches},

author = {Dehbi, A. and Badreddine, H.},

abstractNote = {In CFD simulations of flow mixing in a steam generator (SG) during natural circulation, one is faced with the problem of representing the thousands of SG U-tubes. Typically simplifications are made to render the problem computationally tractable. In particular, one or a number of tubes are lumped in one volume which is treated as a single porous medium. This approach dramatically reduces the computational size of the problem and hence simulation time. In this work, we endeavor to investigate the adequacy of this approach by performing two separate simulations of flow in a mock-up with 262 U-tubes, i.e. one in which the porous media model is used for the tube bundle, and another in which the full geometry is represented. In both simulations, the Reynolds Stress (RMS) model of turbulence is used. We show that in steady state conditions, the porous media treatment yields results which are comparable to those of the full geometry representation (temperature distribution, recirculation ratio, hot plume spread, etc). Hence, the porous media approach can be extended with a good degree of confidence to the full scale SG. (authors)},

doi = {},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2012},

month = {7}

}