Early development of artificially initiated turbulent spots. (6th April 2021)

• Record Type: Journal Article
• Authors: Wang, Y. X.; Choi, K.-S.; Gaster, M.; Atkin, C.; Borodulin, V.; Kachanov, Y.
• Is Part Of: Journal of fluid mechanics. Volume 916(2021)
• Publication Date: 2021-04-06
• Subjects: transition to turbulence, -- boundary layer stability, -- boundary layer structure; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2021.152
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract: 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.