Turbulence instabilities and passive scalars in rotating channel flow
2011 (English)In: 13th European Turbulence Conference (ETC13): Instability, Transition, Grid Turbulence And Jets / [ed] K. Bajer, Institute of Physics Publishing (IOPP), 2011, 032025- p.Conference paper (Refereed)
Fully developed channel flow with a passive scalar rotating about the spanwise axis is studied by direct numerical simulations. The Reynolds number based on the bulk mean velocity Re-b is up to 30000, substantially higher than in previous studies, and the rotation rates cover a broad range. Turbulence on the stable channel side is less strongly damped at moderate rotation rates than in channel flow at lower Re-b. At high rotation rates and sufficiently high Re-b, intermittent strong instabilities occur on the stable side caused by rapidly growing modes resembling two-dimensional Tollmien-Schlichting waves which at some instant become unstable and break down into intense turbulence. The turbulence decays and after some time the waves form again and the process is repeated in a cyclic manner. Rotation also strongly affects the mean passive scalar profiles and turbulent scalar fluxes. Large scalar fluctuations are observed on the border between the stable and unstable channel sides. While in non-rotating channel flow the turbulent Prandtl number of the passive scalar is about one like in other shear flows, it is much smaller in the rotating cases.
Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2011. 032025- p.
, Journal of Physics: Conference Series (Print), ISSN 1742-6588 ; 318
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-86797DOI: 10.1088/1742-6596/318/3/032025ISI: 000301336300025ScopusID: 2-s2.0-84856348063OAI: oai:DiVA.org:kth-86797DiVA: diva2:501027
13th European Turbulence Conference. Warsaw. 12 - 15 September 2011
QC 201204102012-02-132012-02-132012-04-26Bibliographically approved