Smoke observations of the formation of a Kármán vortex street

A smoke visualization technique was used to study the laminar wake behind a single cylinder. Observations of the wake revealed the nature of the process of formation of a Kármán vortex street: instability of the shear layers was coupled with the rolling up process induced by the concentration of vorticity. An unexpected mass transfer was observed through the Kármán vortex street which cause mixing of the fluid surrounding the wake.