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P. Liu
Fig. 1.88 Large-scale vortices (two co-directional vortices and one near-wall vortices
coiling, convection, and diffusion dominate)
mesoscale eddies, we can see that only when the large-scale eddies cannot be
maintained and break up rapidly, the evolution process of mesoscale eddies
will occur. The shortest period in the whole process is the fast decay period,
as shown in Fig. 1.89. (3) The small-scale eddy dissipation period belongs to
the later stage of turbulent decay, as shown in Fig. 1.90. During this period,
the small-scale eddies are mainly affected by viscous diffusion and dissipation, and convection is very weak. It belongs to the slow dissipation period
of the small-scale eddies. The whole process takes a long time. The energy of
the turbulent eddies is mainly dissipated by viscous energy in the first-scale
eddies. These need further experimental verification.
Fig. 1.89 Mesoscale eddies (large eddies rapidly broken, mesoscale eddies transition)