  It is argued that ejections of wall fluid in the bursting process disturb the
flow beyond the wall layer and result in the emergence of two new layers in the
flow field: the law of the wake and log-law layers. The wall layer represents
the extent of penetration of viscous momentum into the main flow and remains
constant once it has reached a critical value at the end of the laminar regime.
The identification of the three flow regimes: laminar, transition and fully
turbulent is conveniently achieved by monitoring the emergence of these three
layers
