CFD simulation of a heated round jet of sodium in forced flow regime (TEFLU benchmark)
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Data
2000-11-17
Autori
Aragonese, Cosimo
Buono, Stefano
Fotia, Giorgio
Maciocco, Luca
Moreau, Vincent
Sorrentino, Luca
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Abstract
The results of the simulation of the forced-flow case of the TEFLU benchmark [1], obtained at
CRS4 with the Star-CD code, are reported. First, a comparison among different k-ε turbulence models implemented in Star-CD was carried out. The Chen k-ε model [4], [5] gave the best agreement with experimental results.
Then, a study of the influence of the turbulent Prandtl number Prt was carried out. The first step
was the comparison between the molecular conductivity and the turbulent heat diffusion
coefficients, calculated using the turbulent Prandtl number approach (Reynolds analogy). It was
found that that the two contributions are of the same order of magnitude. This result implies that
there is a strong interaction between the molecular and turbulent heat transfer, which could have a
strong effect on the scaling coefficient between the turbulent transfer of momentum and heat,
namely on Prt. In order to study the effect of the variation of Prt on the temperature profiles, the inlet turbulence kinetic energy profile was scaled in order to obtain a good agreement between calculated and experimental velocity profiles. Then, the value of Prt was changed from the standard value of 0.9 to 10 (on the basis of the considerations of Jisha and Rieche [6]) and to 104 (to exclude the
contribution of the turbulent heat transfer). A very good agreement with experimental
measurements was found in both cases (the best being the case of no turbulent heat transfer).
The above results indicate that the heat conduction is predominant in the forced-flow case. In this
situation, the standard value 0.9 of Prt yields an overestimation of the thermal diffusion rate.
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Keywords
CFD , turbulence model , forced-flow