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Gas dynamics is a branch of fluid mechanics which deals with compressible flow. The unique aspects of gas dynamics include two phenomena that not do appear in other branches of fluid mechanics. These phenomena are waves (normal shocks , oblique shock and expansion waves) and choking flow (isentropic, isothermal choking). A parallel to the shock seen in gas dynamics is the hydraulic jump witnessed in open-channel incompressible flow. Nevertheless, the shock in many aspects which don't appear in the hydraulic jump, e.g. oblique shock. Choking occurs when there is a disparity between the area difference of the nozzle and the throat and the pressure drop between the inlet and outlet, causing the creation of a shock wave before the outlet to make up for that difference. Study of gas dynamics involves,

• Shock wave e.g. normal shock, oblique shock and detonation waves
• Isentropic flow e.g. isentropic compression and expansion, Prandtl-Meyer expansion fan
• External flows e.g. Thin airfoil theory
• Internal flows e.g. Fanno flow, Rayleigh flow, flow through nozzles

Contents 1 History 2 See also 2.1 Important concepts 2.2 Flows of interest 2.3 Experimental techniques 2.3.1 Visualisation methods 2.4 Computational techniques 2.5 Aerodynamics 3 References 4 External links

Gas dynamics became important during World War II due to its potential military applications. Other applications include manufacturing (die casting), and a myriad of other possibilities including the expansion of the gas that occurs when an airbag inflates in a motor vehicle. Many of the basic physical understandings were achieved 1940-1960 after which it became classical material. Yet many of the mathematical underline of the many principles were achieved only in this millennium e.g. oblique shock, moving shock.

Mach number Mach wave Normal shock Oblique shock Moving shock Prandtl-Meyer expansion fan

Compressible flow Transonic flow Supersonic flow Hypersonic flow Choked flow De Laval nozzle Fanno flow Rayleigh flow

Shock tube Transonic, supersonic, hypersonic wind tunnels. Shadowgraph Schlieren photography Mach-Zehnder interferometer

• Wave drag
• Sonic boom
• Whitcomb area rule
• Supercritical airfoil
• Supersonic transport

• Liepmann, Hans W.; Roshko, A. [1957] (2001). Elements of Gasdynamics. Dover Publications. ISBN 0-486-41963-0. 
• Anderson, John D. Jr. [1984] (January 2001). Fundamentals of Aerodynamics, 3rd Edition, McGraw-Hill Science/Engineering/Math. ISBN 0-07-237335-0. 
• Shapiro, Ascher H. [1953]. The Dynamics and Thermodynamics of Compressible Fluid Flow, Volume 1. Ronald Press. ISBN 978-0-471-06691-0. 
• Zucker, Robert D.; Biblarz O. (July 2002). Fundamentals of Gas Dynamics. John Wiley & Sons. ISBN 0471059676. 
• Vincenti, Walter G. [1965] (2002). Introduction to Physical Gas Dynamics. Krieger publishing company. ISBN 0-88275-309-6. 
• Anderson, John D. Jr. [1989] (2000). hypersonic and High Temperature Gas Dynamics. AIAA. ISBN 1-56347-459-X. 

• Fundamentals of compressible flow