On the various swept wings that make up the fins of a missile, a red emission reveals the positions of the upper surface vortices, and in particular their curving towards the axial jet, which acts as a sink for the external flow.

The blue streak emitted along the body shows an annular zone of separated flow, which remains between the straight base and the jet orifice boundaries.

Apart from their aerodynamic studies, jets and vortices are the subject of research as regards noise reduction.

Image created by Henri Werlé. Reproduced with permission from his spectacular collection Courants et Couleurs published in 1974 by ONERA, the French Aerospace Lab.