What occurs in a convergent duct with respect to velocity and pressure?

In a convergent duct, the cross-sectional area decreases, which leads to an increase in the velocity of the fluid (or gas) flowing through it. According to the principle of conservation of mass and Bernoulli's principle, as the area decreases, the fluid must speed up to maintain a constant mass flow rate. This phenomenon is often observed in fluid dynamics and can be explained by the continuity equation, which asserts that for incompressible flow, the product of the cross-sectional area and the velocity must remain constant along the streamline.

As the velocity of the fluid increases in the convergent duct, the static pressure conversely decreases. This is also a result of Bernoulli's principle, which indicates that in a streamline flow, an increase in the velocity of the fluid is associated with a decrease in its potential energy, which is represented as static pressure in the system.

Therefore, in a convergent duct, the resultant effect is that the velocity increases while the static pressure decreases, making this option the accurate choice.