Please explain the terms below.

$-$Rotational Flow:

$-$Specify the continuity equation and its parameters:

$-$Specify the Euler equation and its parameters:

$-$The jet stream is close to uniform, so the momentum flux correction factor $\backslash$beta $=1$ is taken. give an example of situations where $\backslash$beta is different from $1.$

$-$What are the parameters that determine the characteristic when making the selection? What should be considered as input diameter and output diameter external parameters?