"Bernoulli's Theorem" states that as the diameter of the tube is increased, flow velocity increases with a substantial "drop" in pressure! This would actually increase the exhaust gas velocity.
My apologies to "Bernoulli" his theorem actually states that as the diameter is reduced, you have an increase in velocity and a decrease in pressure.
So if our hose had a constriction in the middle, flow though that area would have to be accelerated, and pressure would drop in that local area....once the hose "opened" back up velocity would slow, and pressure would go back up...
For accuracy I should acknowledge that water is not compressible, "air" is compressable, so water is not a perfect medium, but water is helpful to "envision" flow.
The Chinese purchase of the SU-35 will be their first experience with OVT,,,, they are going to love it, the Flanker is a beautiful airplane that thrives with OVT to help it get the "lead out". To be honest as an aft delta, the J-20 would actually benefit more from OVT than the Flanker or Raptor due to the center of lift/center of gravity being farther aft, while the distant coupled canards "lift the nose or drive it down, OVT on the other end would really hasten "pitch transitions" and that is the name of the game in fighter maneuverability.
So China's actual purchase of those SU-35s could be an anomaly, or it could be a harbinger of change, either way, it is a "grabber"....
