DOI: 10.1615/ICHMT.2014.IntSympConvHeatMassTransf
ISBN Print: 978-1-56700-356-7
ISSN Online: 2642-3499
ISSN Flash Drive: 2642-3502
EVALUATION OF TURBULENCE AND MASS TRANSFER MODELS ON SCALAR DISPERSION IN TURBULENT ANNULAR FLOW
ABSTRACT
Turbulent scalar mixing from a line mass source in an annular flow has been numerically investigated by using DNS and RANS simulations. The scalar mixing in turbulent shear flow is a physical phenomenon involved in various engineering applications. In particular, the boron dilution and mixing phenomenon is one of the safety issues in the nuclear safety analysis related to the reactivity excursion of the reactor core. In this study, the evaluation of the predictive capacity of turbulence and turbulent scalar flux models that are commonly used in the RANS analysis is conducted by using DNS. It was learned that the mean velocity distributions of the SST, EARSM and RSM-ω turbulence closure models were in good agreement with the DNS results, but for the SA model, a distribution with higher velocities in the core region was observed. It was also observed that in the RANS analyses results when using the turbulent Schmidt number (Sct), the results were in relatively good agreement with the DNS results when Sct~1.5. Detailed results from the DNS analysis were invoked to evaluate the generalized gradient diffusion model for turbulent scalar flux. In addition, the transport equations of the turbulent scalar flux were derived and the turbulent scalar production budget was computed by using the DNS data. The result of this study on turbulent scalar mixing in annular flow can not only provide basic data for CFD analyses on boron dilution and mixing in nuclear safety analysis but can also be used in scalar transport analyses for various applications, such as thermal mixing.