Large-scale, coherent structures in wide-aspect-ratio, turbulent, Rayleigh-benard convection

P. J. Sakievich, Yulia Peet, Ronald Adrian

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

Abstract

Investigation of the spatial organization of large-scale, coherent structures in turbulent, Rayleigh-Bénard convection is performed through direct numerical simulation. The simulation is performed in a 6.3 aspect ratio cell with a Rayleigh number of 9.6 × 107 and Prandtl number equal to 6.7. Single and double point statistics are compared against experimental results and are found to be in excellent agreement. Large-scale mean thermals with coherence times exceeding 10 eddy-turnovers are discovered and these mean thermals are found to be a reliable tool for identifying and interpreting the large, velocity roll-cells. Our simulations show an existence of a large-scale coherent pattern that consists of three major velocity roll-cells, two of which are semi-toroidal, or horse-shoe shaped, that are connected to the side-walls, and the third roll-cell lies across the center of the cell between the semi-toroidal cells. We present the possible formation mechanism of this nearly-periodic structure, observed at intermediate scales of averaging, as a perturbation from a perfectly periodic, crystal-like, pattern. The dynamics of these structures are evaluated using short-time averages.

Original languageEnglish (US)
Title of host publication9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
PublisherTSFP-9
Volume2
ISBN (Electronic)9780000000002
StatePublished - Jan 1 2015
Event9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 - Melbourne, Australia
Duration: Jun 30 2015Jul 3 2015

Other

Other9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015
CountryAustralia
CityMelbourne
Period6/30/157/3/15

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

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    Sakievich, P. J., Peet, Y., & Adrian, R. (2015). Large-scale, coherent structures in wide-aspect-ratio, turbulent, Rayleigh-benard convection. In 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015 (Vol. 2). TSFP-9.