(2)
or
v = √ (2gh) = 8.025V √ h.
(2a)
That is, neglecting the viscosity of the fluid, the velocity of filaments at the contracted section of the jet is simply the velocity due to the difference of level of the free surface in the reservoir and the orifice. If the orifice is small in dimensions compared with h, the filaments will all have nearly the same velocity, and if h is measured to the centre of the orifice, the equation above gives the mean velocity of the jet.
Case of a Submerged Orifice.—Let the orifice discharge below the level of the tail water. Then using the notation shown in fig. 41, we have at M, v1 = 0, p1 = Gh; + pa at m, p = Gh3 + pa. Inserting these values in (3), § 29,
0 + h1 + pa/G − h1 = v2/2g + h3 − h22 + pa/G;
v2/2g = h2 − h3 = h,
(3)