Key structure in laminar-turbulent transition of boundary layer with streaky structures

Joe Yoshikawa, Yu Nishio, Seiichiro Izawa, Yu Fukunishi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed at providing an environment unstable to outer disturbances. Then, a short duration jet is issued into the boundary layer. When the jet velocity is low, some vortices appear in the boundary layer, but the transition of the boundary layer does not take place. However, when the jet velocity exceeds a certain threshold, two vortices newly appear above the elongated legs of a V-shaped vortex and only one of them is stretched and survives. After that, vortices are generated one after another around the survived one. By comparing the decayed and the survived vortices, it is found that the difference in their heights is the key characteristic which leads to the transition.

Original languageEnglish
Pages (from-to)32-35
Number of pages4
JournalTheoretical and Applied Mechanics Letters
Volume9
Issue number1
DOIs
Publication statusPublished - 2019 Jan

Keywords

  • Boundary layer
  • Key vortical structure
  • Laminar-turbulent transition
  • Numerical simulation
  • Short duration jet
  • Streaky structures
  • Turbulent onset

ASJC Scopus subject areas

  • Computational Mechanics
  • Environmental Engineering
  • Civil and Structural Engineering
  • Biomedical Engineering
  • Aerospace Engineering
  • Ocean Engineering
  • Mechanics of Materials
  • Mechanical Engineering

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