The freestream is the
air
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
far upstream of an
aerodynamic
Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an ...
body, that is, before the body has a chance to deflect, slow down or compress the air. Freestream conditions are usually denoted with a
symbol, e.g.
, meaning the freestream velocity.
References
*Anderson, John D., 1989. ''Introduction to Flight'', 3rd Ed. McGraw-Hill
Aerodynamics
{{Fluiddynamics-stub