Skip to main content Accesibility Help

Continuous mode transition and the effects of pressure gradient

  • TAMER A. ZAKI (a1) and PAUL A. DURBIN (a2)

Continuous mode transition is an instance of the bypass route to boundary-layer turbulence. The stages that precede breakdown are explained in terms of continuous Orr–Sommerfeld and Squire spectra. In that context, the role of pressure gradient is less evident than it is in natural transition. Its role is investigated using linear theory and numerical simulations. Both approaches demonstrate that adverse pressure gradients enhance the coupling of low-frequency vortical disturbances to the boundary-layer shear. The result is stronger boundary-layer perturbation jets – or Klebanoff distortions. The correlation between the intensity of the perturbation jets and transition location is tested by direct numerical simulations of pairwise continuous mode interactions; such interactions can reproduce the entire transition process. The results confirm that stronger perturbation jets are more unstable, and hence provoke early transition in adverse pressure gradient. This is also consistent with the experimental observation that transition becomes independent of pressure gradient at high turbulent intensities. Under such conditions, boundary-layer streaks are highly unstable and transition is achieved swiftly, independent of the mean gradient in pressure.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed