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In learning about aerodynamics for aviation, it has struck me to what extend it is based on a variety of assumptions and presentations, that may one day have served to create a notion of what happens, but don't really clarify the origin of processes such as airlift, drag, turbulence or compressability.

Also are things seemingly missing that one would logically expect to be part of aerodynamics. What is particularly missing are the physics of sound and turbulence, sound undoubtedly being a dynamic component of what happens in air and turbulence being considerably less useless and unpredictable than its given credit for.

Is there a version of aerodynamic rules in which the entire physics of sound is integrated?

  • Related question: Sound speed on Navier-Stokes/Euler equations. That question/answer is relevant because much of the theory of aerodynamics is based on the Navier-Stokes equations. – Chiral Anomaly Mar 28 '21 at 23:16
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    Boundary layer theory incorporates some aspects of sound (Tollmien-Schlichting-waves) where it helps to explain forced transition. Generally, aerodynamics serves to explain and predict the forces on moving solids in a fluid and only includes those aspects which are needed to serve its purpose. The complete physics of sound would only distract from that. Besides, sound propagation and related effects can be easily modelled with the tools of aerodynamics but there is no need to do so. If you have found one, let us know. – Peter Kämpf Mar 29 '21 at 07:40

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Yes. The physics of sound wave propagation in air is explicitly included in trans-sonic and supersonic aerodynamics. The relative importance of sonic effects in aerodynamics is indicated by the so-called Mach number which is the ratio of the vehicle velocity to the local speed of sound; for values of the Mach number equal to ~1, the analysis must include what are called compressibility effects.

niels nielsen
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  • The inclusion of sound wave propagation in air as expressed in trans-sonic and supersonic aerodynamics to my experience is (probably for reasons of practicality) limited to derivatives of the physics of sound to the extend that serves the interest of aviation. What I am looking for is a version of aerodynamics that includes the entirety of the physics of sound rather than a derivative and without being limited to or aiming at any specific purpose or use. –  Mar 29 '21 at 00:32
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    @berend, just look up mach number on wikipedia... The basic concept is as general as it gets and is in no way limited to airflow over wings. – niels nielsen Mar 29 '21 at 04:28
  • I did just now, tnx. The content is very interesting but doesn't reveal what causes sound, or what makes it travel at a constant speed. What it is not that influences it, but that causes just that speed. Why it doesn't slow down or accelerate.. Stuff apparently nobody else has ever been interested in or did so, so secretly it didn't leave any trace. The general focus is on what sound means to objects moving through air, but not on what sound itself is or does. –  Mar 29 '21 at 07:39
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    the physics of sound is a very well-studied topic. entire textbooks have been written on it which include rigorous derivations of the wave equations from first principles. you just need to dig a little deeper. – niels nielsen Mar 29 '21 at 17:09
  • I'm diggin, I'm diggin –  Mar 29 '21 at 17:15
  • Ive got this crazy notion, that the speed of sound has its origin in the separation velocity at evaporation. In order to evaporate, particles must have a certain amount of internal energy.. The separation however, is the result of a tunnel effect between various forces working in opposite directions. That would set the separation energy at a fixed amount, resulting in a fixed separation speed. Fluid dynamics is beautiful in itself, but there ain't no such thing as a fluid, rendering it somewhat off-topic for transition study. Sound is no quantum effect, its 'substantial'. –  Mar 29 '21 at 17:46
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The field of aeroacoustics concerns the propogation of sound waves.

Nick
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  • Aeroacoustics does what you say it does, but it still leaves questions open. The thing is, i have information regarding this, but no proper source to fall back on. It basically claims sound is generated by phase transition, the trigger function of which forcing particles to propagate at a uniform speed in which audible sound is the product of transition incidence and that uniformity. What i need is a basis to calculate how to use sound to regulate turbulence in a way a hurricane does, but smaller and faster and directed. Aeroacoustics doesn't touch that. –  Mar 29 '21 at 02:21