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I was reading Anderson's Modern Compressible Flow and two of his equations were confusing. I attached the relevant pages on this post.

He defined two conditions or state the sonic and stagnation state used to define flows. The sonic state was defined as an adiabatic transition of the flow to M = 1 while the stagnation state was an isentropic transition of the flow to stagnation. However, what confused me was his formulation of Eq. 3.35 and 3.36 on 2.jpg. There he related the stagnation and sonic states of the flow with an isentropic relationship. However, since the sonic state is an adiabatic transition as defined, the entropy may not necessarily be equal to that of the original flow and thus entropy may not be equal to that of the stagnation state?

Any clarification is appreciated.

Thanks

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# Stagnation and Sonic Condition Relationship Question

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