Fun with Physics
05-09-2014, 11:46 AM
#11
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Not a mistake. Slow moving air <M=0.3 is considered incompressible by the discipline of aerodynamics. The context of this thread is hydrodynamics and by extension, aerodynamics. Wikipedia-
Compressible flow (gas dynamics) ) is the branch of fluid mechanics that deals with flows having significant changes in fluid density. Gases, but not liquids, display such behavior. To distinguish between compressible and incompressible flow in gases, the Mach number (the ratio of the speed of the flow to the speed of sound) must be greater than about 0.3 before significant compressibility occurs. The study of compressible flow is relevant to high-speed aircraft, jet engines, gas pipelines, commercial applications such as abrasive blasting, and many other fields.
Compressible flow (gas dynamics) ) is the branch of fluid mechanics that deals with flows having significant changes in fluid density. Gases, but not liquids, display such behavior. To distinguish between compressible and incompressible flow in gases, the Mach number (the ratio of the speed of the flow to the speed of sound) must be greater than about 0.3 before significant compressibility occurs. The study of compressible flow is relevant to high-speed aircraft, jet engines, gas pipelines, commercial applications such as abrasive blasting, and many other fields.
05-09-2014, 12:01 PM
#12
Organizational Learning
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All the qualifiers make my point.
Air IS compressible. Period.
A discipline of aerodynamics considers, that is, pretends, that it is not. The results are close enough to justify the simplification of calculation provided by this assumption.
It is. You said it isn't. Call it whatever makes you feel better.
.
Air IS compressible. Period.
A discipline of aerodynamics considers, that is, pretends, that it is not. The results are close enough to justify the simplification of calculation provided by this assumption.
It is. You said it isn't. Call it whatever makes you feel better.
.
05-09-2014, 03:03 PM
#14
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Position: ATP, CFI etc.
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All in service of better understanding so no harm. A lot of great minds pored over these topics for many years in order to unravel them and it truly is great subject for study. Hydrodynamics was understood before aerodynamics historically, due to ship building over many millennia and the two disciplines are closely related with aerodynamics being built on the solid foundation of hydrodynamics. That surely is not hot air. 
05-09-2014, 06:03 PM
#15
With The Resistance
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Not a mistake. Slow moving air <M=0.3 is considered incompressible by the discipline of aerodynamics. The context of this thread is hydrodynamics and by extension, aerodynamics. Wikipedia-
Compressible flow (gas dynamics) ) is the branch of fluid mechanics that deals with flows having significant changes in fluid density. Gases, but not liquids, display such behavior. To distinguish between compressible and incompressible flow in gases, the Mach number (the ratio of the speed of the flow to the speed of sound) must be greater than about 0.3 before significant compressibility occurs. The study of compressible flow is relevant to high-speed aircraft, jet engines, gas pipelines, commercial applications such as abrasive blasting, and many other fields.
Compressible flow (gas dynamics) ) is the branch of fluid mechanics that deals with flows having significant changes in fluid density. Gases, but not liquids, display such behavior. To distinguish between compressible and incompressible flow in gases, the Mach number (the ratio of the speed of the flow to the speed of sound) must be greater than about 0.3 before significant compressibility occurs. The study of compressible flow is relevant to high-speed aircraft, jet engines, gas pipelines, commercial applications such as abrasive blasting, and many other fields.
Last edited by jungle; 05-09-2014 at 06:17 PM.
05-10-2014, 07:57 AM
#17
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