Circulation around any specific spanwise station, denoted as Γ(yn), is a fundamental aerodynamic concept that quantifies the net rotational motion of air particles around a closed path near a particular location along the span of an aircraft wing or any lifting surface. Circulation is a measure of the strength and direction of the rotational flow of air.
- Γ(yn) is the circulation around the spanwise station “yn.”
- V∞ is the true airspeed of the aircraft.
- c is the local chord length at the station “yn.”
- cl is the local lift coefficient at the station “yn.”