Early development of artificially initiated turbulent spots

Ya Xing Wang, Kwing-So Choi, Mike Gaster, Chris Atkin, Vladimir Borodulin, Yuri Kachanov

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Abstract

An experimental investigation was carried out in a low-turbulence wind tunnel to study the early development of artificially initiated turbulent spots in a laminar boundary layer over a flat plate. The reproducibility of the experiments allowed us to observe fine structural details that have not been observed previously. Initial velocity disturbances quickly developed into hairpin-like structures that multiplied downstream, which increased the width, length and height of the incipient turbulent spots. Only those disturbances that were greater than a threshold value developed into turbulent spots while the others decayed. The
rate of development was also affected by the duration of the initial disturbances. We found that the behaviour of turbulence generation within a turbulent spot is similar to the burst events in the turbulent boundary layer, where ejection events are followed by sweep events.
Original languageEnglish
Article numberA1
Pages (from-to)1-21
Number of pages21
JournalJournal of Fluid Mechanics
Volume916
Early online date6 Apr 2021
DOIs
Publication statusPublished - 10 Jun 2021

Keywords

  • transition to turbulence, boundary layer stability, boundary layer structure

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