Regeneration and Self-Maintaining of Coherent Structures - Transport and Coherent Structures in Wall Turbulence - page 287

observation to what are commonly called very large-scale
structures, which will be discussed in Chapter 6. The
passage of the structures causes high- and low-velocity
streaks, giving rise to the formation of a turbulent spot [HAI
94]. Readers can consult [SMI 91] for a detailed review of
these aspects.
Figure 5.8. Creation and stretching of spanwise vorticity lines and
formation of hairpin structures. The typical dimensions are in inner
variables. This figure is adapted from [HIN 75]
Figure 5.9. Conceptual model proposed by Wallace [WAL 82], stemming
from previous studies and representative of the view in the research
community between 1980 and 1990