Regeneration and Self-Maintaining of Coherent Structures - Transport and Coherent Structures in Wall Turbulence - page 361

established consensus regarding the generation of streaks,
rolls and walls of vorticity by what could be described as

a kinematic effect of the QSVs (Figure 5.41). However, the
mechanism of instability of those streaks has not yet been
clearly defined.

ω ±

y

Figure 5.41. Plausible mechanisms of regeneration
of the coherent near-wall structures

surrounding the streaks
in Figure 5.1 play a fundamentally important role in the
regeneration process. It is impossible to manipulate them
experimentally, but possible to manipulate them using DNS.
Jiménez and Pinelli [JIM 99] identify the layers

The walls of vorticity and ω + ω −

y y

( )

by

ω ± yz ,

y

the spatial mean of

( )

in the streamwise direction

ω x yz ,,

y

L L

1 ∂ u 1

x x

( )

∫ ∫

ω y z , = ω = dx = ω dx [5.103]

y ± y y

Lz ∂ L

x

x x

0 0