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Title: Verification of bubble tracking method and DNS examinations of single- and two-phase turbulent channel flows

Abstract

Direct numerical simulation (DNS) has been regarded as a reliable data source for the development and validation of turbulence models along with experiments. The realization of DNS usually involves a very fine mesh that should be able to resolve all relevant turbulence scales down to Kolmogorov scale [1]. As the most computationally expensive approach compared to other CFD techniques, DNS applications used to be limited to flow studies at very low Reynolds numbers. Thanks to the tremendous growth of computing power over the past decades, the simulation capability of DNS has now started overlapping with some of the most challenging engineering problems. One of those examples in nuclear engineering is the turbulent coolant flow inside reactor cores. Coupled with interface tracking methods (ITM), the simulation capability of DNS can be extended to more complicated two-phase flow regimes. Departure from nucleate boiling (DNB) is the limiting critical heat flux phenomena for the majority of accidents that are postulated to occur in pressurized water reactors (PWR) [2]. As one of the major modeling and simulation (M&S) challenges pursued by CASL, the prediction capability is being developed for the onset of DNB utilizing multiphase-CFD (M-CFD) approach. DNS (coupled with ITM) can be employedmore » to provide closure law information for the multiphase flow modeling at CFD scale. In the presented work, research groups at NCSU and UND will focus on applying different ITM to different geometries. Higher void fraction flow analysis at reactor prototypical conditions will be performed, and novel analysis methods will be developed, implemented and verified for the challenging flow conditions.« less

Authors:
 [1];  [2];  [2];  [1]
  1. Univ. of Notre Dame, IN (United States)
  2. North Carolina State Univ., Raleigh, NC (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1409272
Report Number(s):
ORNL/TM-2017/224
74468
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS

Citation Formats

Tryggvason, Gretar, Bolotnov, Igor, Fang, Jun, and Lu, Jiacai. Verification of bubble tracking method and DNS examinations of single- and two-phase turbulent channel flows. United States: N. p., 2017. Web. doi:10.2172/1409272.
Tryggvason, Gretar, Bolotnov, Igor, Fang, Jun, & Lu, Jiacai. Verification of bubble tracking method and DNS examinations of single- and two-phase turbulent channel flows. United States. doi:10.2172/1409272.
Tryggvason, Gretar, Bolotnov, Igor, Fang, Jun, and Lu, Jiacai. Thu . "Verification of bubble tracking method and DNS examinations of single- and two-phase turbulent channel flows". United States. doi:10.2172/1409272. https://www.osti.gov/servlets/purl/1409272.
@article{osti_1409272,
title = {Verification of bubble tracking method and DNS examinations of single- and two-phase turbulent channel flows},
author = {Tryggvason, Gretar and Bolotnov, Igor and Fang, Jun and Lu, Jiacai},
abstractNote = {Direct numerical simulation (DNS) has been regarded as a reliable data source for the development and validation of turbulence models along with experiments. The realization of DNS usually involves a very fine mesh that should be able to resolve all relevant turbulence scales down to Kolmogorov scale [1]. As the most computationally expensive approach compared to other CFD techniques, DNS applications used to be limited to flow studies at very low Reynolds numbers. Thanks to the tremendous growth of computing power over the past decades, the simulation capability of DNS has now started overlapping with some of the most challenging engineering problems. One of those examples in nuclear engineering is the turbulent coolant flow inside reactor cores. Coupled with interface tracking methods (ITM), the simulation capability of DNS can be extended to more complicated two-phase flow regimes. Departure from nucleate boiling (DNB) is the limiting critical heat flux phenomena for the majority of accidents that are postulated to occur in pressurized water reactors (PWR) [2]. As one of the major modeling and simulation (M&S) challenges pursued by CASL, the prediction capability is being developed for the onset of DNB utilizing multiphase-CFD (M-CFD) approach. DNS (coupled with ITM) can be employed to provide closure law information for the multiphase flow modeling at CFD scale. In the presented work, research groups at NCSU and UND will focus on applying different ITM to different geometries. Higher void fraction flow analysis at reactor prototypical conditions will be performed, and novel analysis methods will be developed, implemented and verified for the challenging flow conditions.},
doi = {10.2172/1409272},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 30 00:00:00 EDT 2017},
month = {Thu Mar 30 00:00:00 EDT 2017}
}

Technical Report:

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  • A theoretical analysis of steady turbulent flow with small solid particulates in suspension has been conducted based on the continuum hypothesis for both phases. The analysis provides the basis for a two-dimensional numerical model capable of predicting dilute two-phase flows. The numerical procedure requires the solution of fully elliptic coupled transport equations for both phases. The turbulence characteristics of the fluid phase are predicted using a two equation (k-epsilon) model of turbulence and involves the calculation of the fluid turbulent kinetic energy (k) and its rate of dissipation (epsilon).
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