Secondary instability in forced wavelength Görtler vortices

Hatsari Mitsudharmadi, S. H. Winoto*, D. A. Shah

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

From an experimental study on the onset of secondary instability in forced wavelength Görtler vortices, it is found that the breakdown process of the Görtler vortices is due to the development of varicose and sinuous mode instabilities. The development of the varicose mode is characterized by the formation of horseshoe vortices that evolve downstream to form mushroom-like structures. This phenomenon is then followed by meandering of the vortices as an indication of the onset of sinuous mode instability, prior to turbulence. The spectrum analysis applied to the fluctuating velocity component shows the occurrence of peak frequency of about 150Hz, which is attributed to the fundamental secondary instability mode with its wavelength comparable to the spanwise wavelength of the primary Görtler vortices, at the location where the mushroom-like structures are clearly depicted in the mean velocity contours on the y-z plane. This confirms that the secondary instability is of the varicose type at the onset that is followed by the sinuous type downstream, prior to the breakdown of the vortices that will lead the boundary layer flow to turbulence. It is also found that the growth rate of the secondary instability observed is about 6.5 times higher than that of the Görtler instability, which leads to a breakdown of the streamwise structures and hence to turbulence.

Original languageEnglish (US)
Article number074104
Pages (from-to)1-8
Number of pages8
JournalPhysics of Fluids
Volume17
Issue number7
DOIs
StatePublished - Jan 1 2005

ASJC Scopus subject areas

  • Condensed Matter Physics

Fingerprint

Dive into the research topics of 'Secondary instability in forced wavelength Görtler vortices'. Together they form a unique fingerprint.

Cite this