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In a convergent nozzle, there is an increase in velocity and a decrease in pressure, but we know that pressure is inversely proportional to area. Then why is this pressure decreased in convergent nozzle, although there is a decrease in area?
The pressure drops in a convergent nozzle because of the Bernoulli Principle.
A nozzle is a spout on the end of a hose or pipe used to control the movement of a fluid like water or air. A convergent nozzle is a nozzle that starts big and gets smaller-a decrease in cross-sectional area. As a fluid enters the smaller cross-section, it has to speed up due to the conservation of mass. To maintain a constant amount of fluid moving through the restricted portion of the nozzle, the fluid must move faster.
The energy to make this fluid speed up has to come from somewhere. Some energy is in the random motion of molecules, which we observe as pressure. The energy in this random motion is converted into faster forward motion, known as stream flow. This change makes the pressure drop.
Pressure is inversely proportional to area, if everything else stays the same. In this case, the energy that causes pressure is converted to another type of energy, so both pressure and area decrease.
