Algebraic Turbulent Heat Flux Model for Prediction of Thermal Stratification in Piping System
NURETH-14 - 2011 September 25-30


Presented at:
NURETH-14
2011 September 25-30
Location:
Toronto, Canada
Session Title:
B1-2 Computational Fluid Dynamics, Mathematical Modeling and Verification/Validation/Applications

Authors:
Marco Pellegrini (Tokyo Institute of Technology)
Hiroshi Endo (Japan Nuclear Energy Safety Organization)
Elia Merzari (Argonne National Laboratory)
Hisashi Ninokata (Tokyo Institute of Technology)
  

Abstract

The effect of stratification on the flow in bounded geometries is studied through computational fluid dynamics (CFD) and two different modeling of the turbulent heat flux, namely constant turbulent Prandtl number and Algebraic Heat Flux Model (AHFM). The main feature of the work is the evaluation of the effect of buoyancy on the thermal quantities, velocity field and related pressure drop. It has been stated the superiority of the AHFM for the evaluation of turbulent heat flux and temperature field together with a correct evaluation of the thickness of the thermal layer (i.e stratification persistence), in comparison with the simple eddy diffusivity approach. However the adopted model shows over-prediction of the momentum transport in the vertical direction in comparison with the experimental data introducing higher uncertainties for the obtained pressure drop and related Fanning friction factor.

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