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SUMMARY:Large-scale motions in supersonic turbulent boundary layers - Gana
 pathisubramani\, B (Imperial College London)
DTSTART:20080911T143000Z
DTEND:20080911T145000Z
UID:TALK13377@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Wide-field and high-speed Particle Image Velocimetry measureme
 nts were performed in a Mach 2 supersonic turbulent boundary layer to char
 acterise the structure of large-scale coherence. Instantaneous velocity fi
 elds in the logarithmic region reveal the presence of elongated uniform lo
 w- and high-speed regions. These elongated regions exhibit strong similari
 ties with the large-scale motions found in incompressible boundary layers.
  Application of Taylor's hypothesis together with high-speed PIV data indi
 cates that these large-scale structures could extend over 30-40 boundary l
 ayer thickness in length. Alternately\, these can interpreted as 5-10 boun
 dary layer thickness long structures lasting over several integral time sc
 ales. Regardless of interpretation\, these elongated (spatio-temporal) str
 uctures appear to be play a significant role in the dynamics of shock-indu
 ced turbulent boundary layer separation. A possible mechanism that relates
  the passage of these elongated structures to the frequency of unsteadines
 s of shock-induced separation will be presented.
LOCATION:Seminar Room 1\, Newton Institute
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