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SUMMARY:‘Spaghetti sandwich’ micro-structure of very high Reynolds num
 ber turbulence - not quite Kolmogorov  - Lord Hunt of Chesterton
DTSTART:20141017T120000Z
DTEND:20141017T130000Z
UID:TALK52738@talks.cam.ac.uk
CONTACT:Aleksandra Przydrozna
DESCRIPTION:Three dimensional tomographic time dependent PIV measurements 
 of high Reynolds number (Re= u’.L/ν) laboratory turbulence (N. Worth at
  CUED) are presented which show the existence of long-lived\, highly shear
 ed thin layer eddy structures with thickness of the order of the Taylor mi
 croscale and internal fluctuations. Similar intermittent highly sheared la
 yer structures are also observed in direct numerical simulations of Ishiha
 ra et al (2014) (in Nagoya) at higher values of Re\, with a comparable lay
 er thickness λ (of order  L Re-1/2 ). Outside these layers the cascade of
  small eddies are distorted as they impact and transfer net energy into th
 e layers –there is also some up-scale transfer as well. Within these ‘
 spaghetti-sandwich‘ layers  intense elongated vortices form\, with the u
 sual Kolmogorov micro- scale L Re-3/4\, where there is intense dissipation
  (of order L/λ times the average value ε)  and velocity fluctuations of 
 order u’- which is not consistent with the overall non-intermittent  Kol
 mogorov-Obukhov (1941) statistical model. The intense shear layers are of 
 practical significance in decorrelating regions of large scale eddying and
  through the influence of their intense internal microscale substructures 
 on particle motions and combustion.\n\nRef: Hunt JCR\, T. Ishihara\, N. Wo
 rth\, Y. Kaneda (2014)\nThin shear layers in high Reynolds number turbulen
 ce-tomographic experiments and a local distortion model. \nJ. Flow Turb Co
 mb vol. 92\, no 3\, pp607-650 (on-line DoI 10.1007) \n\n
LOCATION:LR3B\, Inglis Building\, CUED 
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