Circulation
Circulation may refer to:

Science and technology
Atmospheric circulation, the large-scale movement of air
Circulation (physics), the path integral of the fluid velocity around a closed curve in a fluid flow field
Circulatory system, a biological organ system whose primary function is to move substances to and from cells
Circulation problem, a generalization of network flow problems
Circulation (architecture), the flow of people through a building
Circulation (currency), all currency held by consumers and businesses, but not by financial institutions and governments
Exhaust gas recirculation, a nitrogen oxide reduction technique used in most gasoline and diesel engines
Library circulation, the activities around the lending of library books and other material to users of a lending library
Rhetorical circulation, the ways that texts and discourses move through time and space

Other uses
Print circulation, the average number of copies of a publication
Circulation Festival, an annual circus and fire performance festival held in Dunedin, New Zealand
Circulation (film), a 2008 psychological thriller-fantasy film by Ryan Harper
Circulation (journal), a journal published by the American Heart Association