I have a question regarding shockwaves. So as far as my knowledge, a flow moving at Ma= 1 will create a normal shockwave ($arcsin(1/Ma)$) , and a flow moving faster will cause an oblique shockwave. So can a normal shockwave occur if the flow is diverged with angle Beta, if it was close to speed of sound?


It appears you have a slight misunderstanding with regard to the formation of normal shock wave when a flow moves at Ma = 1. It is not so, when a flow moves at Ma = 1, very weak oblique shock waves called Mach waves are formed at an angle $arcsin(1/Ma)$. Oblique shock wave is formed (not normal shock wave) when the flow is diverted by an angle $\beta$ when greater then the speed of sound.

  • $\begingroup$ ok, thank you for clearing that. So when do normal shockwaves occur? and why dont they occur when the flow is diverted? Is it just nature or is there a scientific explanation for it? $\endgroup$ – QUTADAH Jun 4 '20 at 20:14
  • $\begingroup$ It is usually nature that facilitates the formation of shock waves. If the flow is highly ordered, for example, laminar flows, shock waves won't be formed. Once the flow is subjected to some disturbances, say, abrupt change in cross-sectional area of a flowduct, it results in the formation of shock waves. It is my understanding. $\endgroup$ – G R Krishna Chand Avatar Jun 7 '20 at 2:54

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