Liquids and gases usually have  two types of motion: a laminar flow, which is stable  and smooth; and a turbulent flow, which is composed  of seemingly unorganized swirls.
Liquides et gaz ont d'habitude deux types de mouvement : l'écoulement laminaire, qui est stable et lisse, et l'écoulement turbulent, composé de volutes a priori désordonnées.