Direct Numerical Simulation of Low and Unitary Prandtl Number Fluids in Reactor Downcomer Geometry

Cheng Kai Tai, Tri Nguyen, Arsen S. Iskhakov, Elia Merzari, Nam Dinh, Igor A. Bolotnov

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

Buoyancy effect on low-flow condition convective heat transfer of non-conventional coolants, such as liquid metal and molten salts, is a crucial safety factor to advanced reactors under transient or accidental scenarios. The distinct heat transfer characteristics of non-unitary Prandtl fluids and the inherent complexity of the low-flow mixed convection phenomena requires the development of novel turbulent and heat transfer models that are adaptive to different spatiotemporal scales involved in the mixed convection heat transfer. In this work, direct numerical simulation of low-flow mixed convection is carried out at low-to-unitary Prandtl numbers that are of industrial interest. Time-averaged statistics, turbulent Prandtl number, as well as time signals are analyzed to investigate mixed convection phenomenon. From the time-averaged statistics, buoyant plume altered velocity boundary layer as well as the intensity of the fluctuation near both walls and channel centerline. Buoyancy effect also rendered different degree of convective heat transfer enhancement and impairment depends on Prandtl and Richardson number. Analysis of time series was conducted on the sodium mixed convection case to emphasize on the low-Pr mixed convection behavior at transition region. Resulting power spectra density and wavelet spectrogram suggests possible large convective structure in transition region. Future work will focus on providing broader data coverage on Pr − Re − Ri parameter space to facilitate more comprehensive analysis of mixed convection.

Original languageEnglish (US)
Title of host publicationProceedings of Advances in Thermal Hydraulics, ATH 2022 - Embedded with the 2022 ANS Annual Meeting
PublisherAmerican Nuclear Society
Pages148-161
Number of pages14
ISBN (Electronic)9780894487811
DOIs
StatePublished - 2022
Event5th International Topical Meeting on Advances in Thermal Hydraulics 2022, ATH 2022, held in conjunction with the 2022 American Nuclear Society ,ANS Annual Meeting - Anaheim, United States
Duration: Jun 12 2022Jun 16 2022

Publication series

NameProceedings of Advances in Thermal Hydraulics, ATH 2022 - Embedded with the 2022 ANS Annual Meeting

Conference

Conference5th International Topical Meeting on Advances in Thermal Hydraulics 2022, ATH 2022, held in conjunction with the 2022 American Nuclear Society ,ANS Annual Meeting
Country/TerritoryUnited States
CityAnaheim
Period6/12/226/16/22

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Nuclear Energy and Engineering
  • Nuclear and High Energy Physics

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