1. Coefficient of contraction (Cc)
It is defined as the ratio of area of jet at vena contracta (Ac) to the area of the orifice (A) .
2) Coefficient of Velocity (Cv)
It is deifined as the ratio of the actual velocity of the jet at vena contracta (V0 to the theoritical velocity. (Vth)
3) Coefficient of discharge (Cd)
It is defined as the ratio of the actual discharge through the orifice (Q) to the theoretical discharge (Qth). The coefficient of discharge is wqual to the product of the Cc and Cv.
4) Coefficient of resistance (Cr)
It id defined as the ratio of loss of head in the orifice to the head of water available at the exit of the orifice.