BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Universal character of perturbation growth in near-wall turbulence
  - Nikitin\, N (Moscow)
DTSTART:20080908T132000Z
DTEND:20080908T134000Z
UID:TALK13337@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Spatial instability of fully developed turbulent flow in a lon
 g straight circular pipe is investigated via DNS. The incompressible Navie
 r-Stokes equations are solved with turbulent inflow velocity field extract
 ed from auxiliary streamwise-periodic simulation which run in parallel wit
 h the main spatial simulation. In addition\, small perturbations are intro
 duced into the inlet and velocity difference between the flows with and wi
 thout perturbations is analyzed. It is shown that mean perturbation amplit
 ude $\\varepsilon$ increases exponentially with distance downstream until 
 saturating at the level comparable to the level of turbulent fluctuations 
 in the flow. The rate of the exponential growth is found to be constant wh
 en normalized by viscous length\, $\\varepsilon\\sim\\exp(0.002x^+)$ over 
 the considered Reynolds number range $140\\leqslant\\Re_\\tau \\leqslant32
 0$. The universal character of perturbation growth is confirmed also by ch
 annel flow simulations
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR