Contents preface (VII) introduction 1—37

17.5.1. Hydraulic Jump-Type Stilling Basins
Selection of a suitable type of stilling basin depends upon the characteristics of the hydraulic jump that would form. The characteristics of the jump, in turn, depend on the Froude number of the incoming flow as has been illustrated in Fig. 17.20. For Froude numbers between 1.0 and 1.7, the depth of incoming flow is only slightly less than the critical depth. The change from supercritical stage to subcritical stage is gradual and the water surface is only slightly ruffled. For Froude numbers between 1.7 and 2.5, surface rollers are formed but the flow is still relatively smooth (form A of Fig. 17.20). For Froude numbers between 2.5 and 4.5, the incoming jet intermittently flows near the bottom and along the water surface and thus forms


Form A - Pre - Jump stage (1.7 < F ₁ < 2.5)
Oscillatring jet

Roller

Form B - Transition stage (2.5 < F₁ < 4.5)

Form C - Range of well balanced jumps (4.5 < F ₁ < 9.0)

Form D - Effective jump but rough surface downstream (F₁ > 9.0)