Two passive methods were discussed, in particular: internal manipulators, or “riblets”, (surface modification in the form of longitudinal striations) and external manipulators, or “LEBU's” also described as Outer Layer Devices, blades or ribbons, consisting of thin flat plate or aerofoil section devices embedded within the flow.
Deux méthodes passives furent essentiellement considérées, faisant appel aux manipulateurs internes, soit “riblets”, (modification de la surface sous la forme de fines rainures longitudinales) et aux manipulateurs externes “LEBU”, petites lamelles rectangulaires ou petits manipulateurs profilés insérés dans l'écoulement.springer springer