Negative streamwise velocities and other rare events near the wall in turbulent flows
2011 (English)In: 13th European Turbulence Conference (ETC13): Wall-Bounded Flows And Control Of Turbulence, Institute of Physics Publishing (IOPP), 2011, 022013- p.Conference paper (Refereed)
Negative streamwise velocities, extreme wall-normal velocites and high flatness values for the wall-normal fluctuations near the wall are investigated for turbulent channel flow simulations at a series of Reynolds numbers up to Reτ = 1000 in this paper. Probability density functions of the wall-shear stress and velocity components are presented, as well as joint probability density functions of the velocity components and the pressure. Backflow occurs more often (0.06% at Reτ = 1000) and further away from the wall into the buffer layer for rising Reynolds number. An oblique vortex outside the viscous sublayer is found to cause this backflow. Extreme v events occur also more often for rising Rey nolds number. Positive and negative velocity spikes appear in pairs, located on the two edges of a strong streamwise vortex: the negative spike occurring in a high speed streak indicating a sweeping motion, while the positive spike is located between a high and low speed streak. These extreme v events cause high flatness values near the wall (F(v) = 43 at Reτ = 1000).
Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2011. 022013- p.
, Journal of Physics: Conference Series (Print), ISSN 1742-6588 ; 318
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-41273DOI: 10.1088/1742-6596/318/2/022013ISI: 000301292300013ScopusID: 2-s2.0-84863011882OAI: oai:DiVA.org:kth-41273DiVA: diva2:443496
13th European Turbulence Conference (ETC) Location: Univ Warsaw, Warsaw, Poland, Date: SEP 12-15, 2011
QC 201109262011-09-262011-09-262012-04-10Bibliographically approved