The Trends

The trends or whether the variables are increasing or decreasing can be observed from looking at the equation developed. For example, the pressure can be examined by looking at equation (9.26). It demonstrates that the Mach number increases downstream when the flow is subsonic. On the other hand, when the flow is supersonic, the pressure decreases.

The summary of the properties changes on the sides of the branch

	Subsonic	Supersonic
Pressure, $P$	decrease	increase
Mach number, $M$	increase	decrease
Velocity, $U$	increase	decrease
Temperature, $T$	decrease	increase
Density, $\rho$	decrease	increase
Stagnation Temperature, $T_0$	decrease	increase

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