THEORY OF FLOW OF FLUIDS
Streamline (or steady) flow of fluids:
The flow of a fluid is said to be streamlined or steady, if at any given point, the velocity of each flowing fluid particle (both in magnitude and direction) remains constant in time.
STREAMLINE: The path of a fluid particle under steady flow is called a streamline.
It is defined as the curve whose tangent at any point gives the direction of fluid velocity at that point.
EQUATION OF CONTINUITY is basically a statement of conservation of mass of a fluid in steady flow.
Velocity of efflux ie. the velocity with which a liquid flows out of an orifice is equal to that which a freely falling body would acquire in falling through a vertical distance equal to the depth of the orifice below the free surface of the liquid.
FOR MORE DETAILS, WHICH NEEDS EQUATION, PLEASE VIEW THE FOLLOWING DOCUMENT