Direct Numerical Simulation of Low and Unitary Prandtl Number Fluids in a Simultaneously Cooled Vertical Channel

Cheng Kai Tai, Tri Nguyen, Elia Merzari, Igor A. Bolotnov

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

1 Scopus citations

Abstract

Understanding vertical mixed convection of low-to-unitary Prandtl fluids is the backbone to the passive heat removal assessment in the advanced reactors designs. Buoyancy effect could give rise to considerable impact on the convective heat transfer. Currently, there is a need for high-resolution data to support modeling of this complicated phenomenon. A series of direct numerical simulations is carried out to study the low flow mixed convection of liquid metals and unitary Prandtl in a downcomer-representing vertical channel. We further focus on the simultaneous cooling downflow scenario, in which the buoyancy is aligned with the direction of bulk flow. In this scenario, the buoyancy accelerates of the flow within range of thermal boundary layer. The acceleration first caused laminarization of the turbulence and accompanied by the surge of the high-velocity sweep near the walls. The unitary Prandtl fluid was identified to be more susceptible to the buoyancy effect in this case, owing to the inhomogeneity of the temperature across the walls. The laminarization also rendered considerable impairment of convective heat transfer because of the reduced turbulent heat transfer. Also note that the flow regime transition could span across the channel at the low buoyancy cases, which may pose challenge for the turbulence modeling. For the liquid metals, the high thermal diffusivity rendered low temperature difference between the near wall and the bulk fluid. Hence the establishment of the buoyancy effect is more visible at strong buoyancy cases.

Original languageEnglish (US)
Title of host publicationProceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023
PublisherAmerican Nuclear Society
Pages1219-1232
Number of pages14
ISBN (Electronic)9780894487934
DOIs
StatePublished - 2023
Event20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023 - Washington, United States
Duration: Aug 20 2023Aug 25 2023

Publication series

NameProceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023

Conference

Conference20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023
Country/TerritoryUnited States
CityWashington
Period8/20/238/25/23

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Instrumentation

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