Direct numerical simulation of pebble bed flows: Database development and investigation of low-frequency temporal instabilities

Lambert H. Fick, Elia Merzari, Yassin A. Hassan

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Computational analyses of fluid flow through packed pebble bed domains using the Reynolds-averaged Navier-Stokes (RANS) framework have had limited success in the past. Because of a lack of high-fidelity experimental or computational data, optimization of Reynolds-averaged closure models for these geometries has not been extensively developed. In the present study, direct numerical simulation (DNS) was employed to develop a high-fidelity database that can be used for optimizing Reynolds-averaged closure models for pebble bed flows. A face-centered cubic (FCC) domain with periodic boundaries was used. Flow was simulated at a Reynolds number of 9308 and cross-verified by using available quasi-DNS data. During the simulations, low-frequency instability modes were observed that affected the stationary solution. These instabilities were investigated by using the method of proper orthogonal decomposition, and a correlation was found between the time-dependent asymmetry of the averaged velocity profile data and the behavior of the highest-energy eigenmodes. Finally, the effects of the domain size and the method of averaging were investigated to determine how these parameters influenced the stationary solution. A violation of the ergodicity assumption was observed.

Original languageEnglish (US)
Article number051301
JournalJournal of Fluids Engineering, Transactions of the ASME
Volume139
Issue number5
DOIs
StatePublished - May 1 2017

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

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