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Article

Transition delay by means of base flow modulations

Authors: Sattarzadeh, S. S., Shahinfar, S., Fallenius, B. E. G. , Fransson, J. H. M., Talamelli, A.
Document Type: Conference
Pubstate: Published
Journal: Bulletin of the American Physical Society, 64th Annual Meeting of the APS Division of Fluid Dynamics, Baltimore, November 20-22 2011
Volume:   
Year: 2011

Abstract

Recent experimental investigations have shown that spanwise modula- tions of the base flow may delay transition to turbulence2. In this study we explore the possibility to generate streaks of much larger amplitude than previously reported by using a row of miniature vortex generators (MVGs). Here, we present the rst boundary layer experiment where streak amplitudes exceeding 30% have been produced without having any secondary instability acting on them. Furthermore, the induced skin-friction drag due to the streaky base flow is quanti ed and it is demonstrated that the streaks can be reinforced by placing a second array of MVGs downstream of the rst one. In this way it is possi- ble to make the control more persistent in the downstream direction. We conclude that the specially designed set of MVGs, as a boundary layer modulator, is a promising candidate for successfully setting up robust and persistent streamwise streaks, which is a prerequisite for a successful flow control. This work is carried out within the AFRODITE programme funded by ERC.