Circulation () around a closed curve in fluid dynamics is a measure of the rotational motion of fluid particles as they flow along the path of the curve. It quantifies the tendency of fluid elements to circulate or rotate around the closed path due to the presence of vortices or flow patterns.
- is the circulation around one portion of the closed curve three.
- is the circulation around another portion of the closed four.
- is the total circulation around the entire closed cure two.