Question

The formation of hydraulic jump at the foot of a spillway is one of the common methods of energy dissipation because ______________________

(a) it destroys more than 90% of total energy by the turbulence produced in the jump

(b) it reduces the kinetic energy by increasing the depth of flow

(c) its action is not understood

(d) it reduces the kinetic energy by decreasing the depth of flow

This question was posed to me in exam.

This is a very interesting question from Energy Dissipation Below Overflow Spillway in section Spillways, Energy Dissipators and Spillway Gates of Irrigation Engineering

Answer 1

The correct answer is (a) it destroys more than 90% of total energy by the turbulence produced in the jump

The explanation is: Hydraulic jump is generally accompanied by large scale turbulence dissipating most of the kinetic energy of the super-critical flow. It is the most suitable method because the energy is lost in the impact of the water against water. Most of the kinetic energy is destroyed by creating a condition suitable for the hydraulic jump.