For a streamline flow,

In a streamline flow, the velocity of the fluid at any fixed point in space remains constant with time.

As a fluid particle moves from one point to another along a streamline, its velocity and speed can change depending on the cross-sectional area of the tube of flow, in accordance with the equation of continuity ($A_1 v_1 = A_2 v_2$). Thus, the velocity and speed of a given particle do not necessarily remain constant.

Since the velocity at any specific point is constant, all fluid particles arriving at that point will possess the exact same velocity.

As a result, all particles arriving at a specific point will have identical momenta and identical kinetic energies.