On page 462 in the chapter summary (aka «glossary») for chapter 17 the entry for shock wave has multiple problems.
Experts in the field prefer to call it a _shock_ rather than a «shock wave».
The description conical or wedge-shaped is confusing. A real wedge is of course a 3D object:
I thought the book was referring to a wedge-shaped shock in 3D, such as one sees bound to the wing of an aircraft in transonic flight:
However, after thinking about it for a long, long time I now suspect that the intent was to say conical (in 3D) or vee-shaped (in 2D) or something like that.
The entry reads like the definition of sonic boom not shock per se. A sonic boom is an example of a shock, but certainly not the only example. In particular, the book refers to a supersonic source object, but in reality it is common to have a shock without any such source. An example is the normal shock attached to a high-subsonic wing (above). Another example is the normal shock in a rocket nozzle. An even more spectacular example is shock diamonds.
It is unhelpful to define the shock in terms of piling up wavefronts because in accordance with the Huygens principle, every wave you've ever seen can be described that way.
Combining the three previous points: Note that it is perfectly possible to have a shock in 1D. In fact most serious discussions of the shock equations start with the 1D case ... and do not describe it in terms of piling up wavefronts.
Also note that a sonic boom is not necessarily strictly conical, for example if the source object is turning.
Earlier in the chapter, on page 459, it says emphatically that a shock is produced even if the object emits no sound. That seems spectacularly self-contradictory. Have you ever heard a sonic boom? It sounds like sound to me. Also it's inconsistent with the idea of constructing the shock front by piling up wavefronts. I have no idea what the intent was here.
Suggestions:
First, figure out whether the intent was to define sonic boom or define shock in general. Then it becomes possible to address the issues itemized above.
On page 462 in the chapter summary (aka «glossary») for chapter 17 the entry for
shock wavehas multiple problems.conical or wedge-shapedis confusing. A real wedge is of course a 3D object:I thought the book was referring to a wedge-shaped shock in 3D, such as one sees bound to the wing of an aircraft in transonic flight:
conical (in 3D) or vee-shaped (in 2D)or something like that.sonic boomnot shock per se. A sonic boom is an example of a shock, but certainly not the only example. In particular, the book refers to a supersonicsourceobject, but in reality it is common to have a shock without any such source. An example is the normal shock attached to a high-subsonic wing (above). Another example is the normal shock in a rocket nozzle. An even more spectacular example is shock diamonds.piling up wavefrontsbecause in accordance with the Huygens principle, every wave you've ever seen can be described that way.even if the object emits no sound. That seems spectacularly self-contradictory. Have you ever heard a sonic boom? It sounds like sound to me. Also it's inconsistent with the idea of constructing the shock front bypiling up wavefronts. I have no idea what the intent was here.Suggestions:
First, figure out whether the intent was to define
sonic boomor defineshockin general. Then it becomes possible to address the issues itemized above.