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

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

3. GEN-BL: Transition-Delay by Upstream Flow Deformation
With excitation of closer-spaced vortices upstream (UFD)
“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 growth independent 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. GEN-BL: Convective nature of Secondary Instability - DNS
t = t0
Switching-off the background pulses
 relaxation to steady saturated state
t = t0+3T
Alle instationären Störungen werden stromab konvektiert
Letztendlich wieder stationärer Sättigungszustand mit ausgeprägten Längswirbeln
Was sieht man gleich in der Animation
Bewies des konvektiven Charakters
t = t0+6T
Isofläche 2