Question

Find the discharge through totally drowned orifice of width 2.3 m if the difference of water levels on both side of the orifice be 40 cm. The height of water from to and bottom of the orifice are 2.6 m and 2.75 m respectively.

(a) .56 m^3/s

(b) .64 m^3/s

(c) .75 m^3/s

(d) .55 m^3/s

This question was addressed to me at a job interview.

This intriguing question originated from Classification of Orifice & Hydraulic Coefficients in section Fluid Dynamics of Fluid Mechanics

Answer 1

Correct choice is (a) .56 m^3/s

The best explanation: Q = Cd * b * (H2 – H1) √2gH

                    Here, b = 2.3

                             H2 = 2.75

                             H1 = 2.6

                             H = 40

                     Q = .56 m^3/s.