Hierarchy of minimal flow units in the logarithmic layer

The minimal simulation boxes of the buffer layer of turbulent channels can be extended to the logarithmic and outer regions, where they contain a segment of streamwise velocity streak, and a vortex cluster. Smaller boxes restrict “healthy” turbulence closer to the wall, to a layer whose thickness scales with the spanwise size of the box. These minimal boxes burst quasiperiodically, and the bursting period for a band of wall distances grows linearly away from the wall, independently of the box size within the limits within which turbulence is well represented.