Under the condition that both the converging nozzle and the parallel nozzle maintain constant flow rate, does the fluid need to pass through the converging nozzle under greater pushing pressure than the non converging nozzle?
We all know that according to Bernoulli's law, if the cross-sectional area of a pipe decreases, the velocity of the fluid will increase and the pressure will decrease. The minimum section has the lowest pressure and the highest speed. Someone told me that in a convergent nozzle, pressure gradually decreases, and the reason why pressure decreases is because pressure can be converted into kinetic energy. So there is no need for greater push pressure. They use Bernoulli's law to illustrate this point:
$P_1+0.5ρV_1^2=P_2+0.5ρV_2^2$
They say that pressure $P_2$ is smaller than $P_1$, so $V_2$ is greater than $V_1$. No need to increase pressure. The energy for increasing speed is converted from pressure energy.
I think what they said is wrong. If the flow rate remains constant, compared to non converging nozzles, greater pressure should be required to allow the fluid to pass through the converging nozzle at a higher speed. Am I wrong?
