Large Scale Motions in Turbulent Flows

0503334 - ÚT 2020 RIV CZ eng C - Conference Paper (international conference)
Kellnerová, Radka - Jurčáková, Klára (ed.) - Procházka, Pavel P.
Large Scale Motions in Turbulent Flows.
Proceedings of Topical Problems of Fluid Mechanics 2019. Praha: Institute of Thermomechanics of the Czech Academy of Sciences, 2019, s. 117-122. ISBN 978-80-87012-69-7. ISSN 2336-5781.
[Topical Problems of Fluid Mechanics 2019. Prague (CZ), 20.02.2019-22.02.2019]
R&D Projects: GA ČR GA15-18964S; GA ČR(CZ) GA18-09539S
Institutional support: RVO:61388998
Keywords : wind tunnel * large scale motion * quadrant analysis
OECD category: Applied mechanics
http://www.it.cas.cz/fm2015/im/admin/showfile/data/my/Papers/2019/17-TPFM2019.pdf

Quadrant analysis based on the Reynolds decomposition was performed on the data from turbulent boundary layer flows above variously rough surfaces. An estimation of a convective velocity for events significant in terms of momentum flux, and the statistics of a length and amplitude of the individual events, together with their spectral analysis, was performed. Based on the analyses, we were able to detect a few individual sweep and ejection events with a length longer than 6δ, which could be considered as very large scale motions (VLSM). We also identified number of events with a longitudinal dimension equal to approximately 3δ labelled as large scale motions (LSM). The analyses were executed for various Reynolds numbers. The number of detected structures increases with the momentum of the flow.
Permanent Link: http://hdl.handle.net/11104/0298407