Why thrust decreases then increases with velocity?

[dale_8888]

Hello,

I was trying to find out why net thrust decreases then increases with velocity. I recall there is pressure and momentum thrust, however I can not recall why one of them falls away and the other increases.

Is momentum thrust the one that picks up as the mass flow increases with increased velocity?

 

[HallsofIvy]

I'm afraid you will have to give more information. What "thrust" are you talking about? Is this a jet engine or a fluid leaving a source under pressure?