Validation and development of DNS database for low Prandtl numbers in rod bundle

Jonathan K. Lai, Elia Merzari, Yassin A. Hassan, Aleksandr Obabko

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

Abstract

Difficulty in capturing heat transfer characteristics for liquid metals is commonplace because of their low molecular Prandtl number (Pr). Since these fluids have very high thermal diffusivity, the Reynolds analogy is not valid and creates modeling difficulties when assuming a turbulent Prandtl number (Prt) of near unity. Baseline problems have used direct numerical simulations (DNS) for the channel flow and backward facing step to aid in developing a correlation for Prt. More complex physics need to be considered, however, since correlation accuracy is limited. A tight lattice square rod bundle has been chosen for DNS benchmarking because of its presence of flow oscillations and coherent structures even with a relatively simple geometry. Calculations of the Kolmogorov length and time scales have been made to ensure that the spatial-temporal discretization is sufficient for DNS. In order to validate the results, Hooper and Wood’s 1984 experiment has been modeled with a pitch-to-diameter (P/D) ratio of 1.107. The present work aims at validating first- and second-order statistics for the velocity field, and then analyzing the heat transfer behavior at different molecular Pr. The effects of low Pr flow are presented to demonstrate how the normalized mean and fluctuating heat transfer characteristics vary with different thermal diffusivity. Progress and future work toward creating a full DNS database for liquid metals are discussed.

Original languageEnglish (US)
Title of host publicationComputational Fluid Dynamics
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791859032
DOIs
StatePublished - Jan 1 2019
EventASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 - San Francisco, United States
Duration: Jul 28 2019Aug 1 2019

Publication series

NameASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019
Volume2

Conference

ConferenceASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019
CountryUnited States
CitySan Francisco
Period7/28/198/1/19

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes

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  • Cite this

    Lai, J. K., Merzari, E., Hassan, Y. A., & Obabko, A. (2019). Validation and development of DNS database for low Prandtl numbers in rod bundle. In Computational Fluid Dynamics (ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019; Vol. 2). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/AJKFluids2019-5036