Aerodynamics

              

  

                 Aerodynamics is a branch of Fluid dynamics concerned with studying the motion of air, particularly when it interacts with a solid object, such as an airplane wing. Aerodynamics is a sub-field of fluid dynamics and gas dynamics, and many aspects of aerodynamics theory are common to these fields. The term aerodynamics is often used synonymously with gas dynamics, with the difference being that "gas dynamics" applies to the study of the motion of all gases, not limited to air.
               Formal aerodynamics study in the modern sense began in the eighteenth century, although observations of fundamental concepts such as aerodynamic drag have been recorded much earlier. Most of the early efforts in aerodynamics worked towards achieving heavier-than-air flight, which was first demonstrated by Wilbur and Orville Wright in 1903.

Branches of aerodynamics

• Incompressible aerodynamics - An incompressible flow is a flow in which density is constant in both time and space. Although all real fluids are compressible, a flow problem is often considered incompressible if the effect of the density changes in the problem on the outputs of interest is small. This is more likely to be true when the flow speeds are significantly lower than the speed of sound. Effects of compressibility are more significant at speeds close to or above the speed of sound. The Mach number is used to evaluate whether the incompressibility can be assumed or the flow must be solved as compressible.
• Subsonic flow - Subsonic (or low-speed) aerodynamics studies fluid motion in flows which are much lower than the speed of sound everywhere in the flow.
• Compressible aerodynamics
• Transonic flow - The term Transonic refers to a range of flow velocities just below and above the local speed of sound (generally taken as Mach 0.8–1.2). It is defined as the range of speeds between the critical Mach number, when some parts of the airflow over an aircraft become supersonic, and a higher speed, typically near Mach 1.2, when all of the airflow is supersonic. Between these speeds, some of the airflow is supersonic, and some is not.
• Supersonic flow - Supersonic aerodynamic problems are those involving flow speeds greater than the speed of sound.
• Hypersonic flow - In aerodynamics, hypersonic speeds are speeds that are highly supersonic. In the 1970s, the term generally came to refer to speeds of Mach 5 (5 times the speed of sound) and above. The hypersonic regime is a subset of the supersonic regime. Hypersonic flow is characterized by high temperature flow behind a shock wave, viscous interaction, and chemical dissociation of gas.

Aerodynamics is important in a number of applications other than aerospace engineering.