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 Exhaust gas recirculation, a nitrogen oxide reduction technique used in most gasoline and diesel engines Ocean circulation, the large-scale movement of water