The freestream is the
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
far upstream of an
aerodynamic
Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...
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