A laminar stream of air flows from a circular tube at Reynolds number 10,000 and is made visible by smoke wire. The edge of the jet develops axisymmetric oscillations, rolls up into vortex rings, and then abruptly becomes turbulent.
On a flat plate, transition from a laminar to a turbulent boundary layer proceeds intermittently through spontaneous random appearance of spots of turbulence.
At Reynolds number 100,000 and 1 deg. angle of attack, transition to turbulence occurs on the plate.
Behind a fine grid, the merging unstable wakes quickly form a homogeneous field. As it decays downstream, it provides a useful approximation to the idealization of isotropic turbulence.
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