Large- and Very Large-scale Structures - Transport and Coherent Structures in Wall Turbulence - page 418

), as
correctly highlighted by Jimenez et al. [JIM 04]. The
structures in the inner sublayer are, therefore, associated
with the high- and low-velocity streaks. The characteristic
streamwise length of these streaks increases by
amalgamation of the wakes of the packets of structures,
which is a purely kinematic process. They are governed by
the wall-normal vorticity, by way of

The first term is negligible when LL

+

>>

+

( k

+

<< k

+

x z x z

k
u kk k

ι ι

≡−

z

ω ≡− ω

y y

2

+

2

x z z

Figure 6.29. Intensity of the shear layers vy in inner variables,

according to Bauer [BAU 14], in the range 180

∂∂

<<

Re 1,100

However, as shown in Figure 1.19, the distribution of the
intensity of the wall-normal vorticity

+

is remarkably

σ

ω

y

independent of Re τ . The wall-normal vorticity is essentially

governed by the shear layers uz delimiting the streaks. ∂∂