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GEN-BL: Secondary Instability of Saturated CF-Vortices*

low-frequency type-III (z)-mode. u s -amplitude in crosscut. high-frequency type-I (z)-mode. w s. u s. GEN-BL: Secondary Instability of Saturated CF-Vortices*. * from a steady mode packet. t-modal amplitude development. „steady“ 2-D. „steady“ 3-D.

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GEN-BL: Secondary Instability of Saturated CF-Vortices*

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  1. low-frequency type-III (z)-mode us-amplitude in crosscut high-frequency type-I (z)-mode ws us GEN-BL: Secondary Instability of Saturated CF-Vortices* *from a steady mode packet t-modal amplitude development

  2. „steady“ 2-D „steady“ 3-D GEN-BL: Secondary Instability of Traveling CF-Vortices medium-frequency 'z-y'-mode high-frequency 'y'-mode moving coordinate system

  3. With excitation ofcloser-spacedvortices upstream (UFD) GEN-BL: Transition-Delay byUpstream Flow Deformation “natural” Wassermann & Kloker (UFD) Saric & al. (DRE) vortices + pulsing + UFD „Natural“ scenario

  4. GEN-BL-APG: small-amplitude vortices + T-S-wave: part III • Increased initial • T-S amplitude • breakdown but: • - T-S just generates secondary crossflow modes • - secondary growthindependent of T-S • (unlike K-type!) • - active control on T-S useless! • (see JFM 530, 2005) vortex mode T-S wave t-z-modal amplitude development t-modal amplitude development

  5. Isofläche 2 GEN-BL: Convective nature of Secondary Instability - DNS t = t0 Switching-offthe backgroundpulses  relaxationto steadysaturated state t = t0+3T t = t0+6T

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