JET FLOW ON STEPPED SPILLWAYSA

The authors presented an interesting discussion of the nappe flow regime above stepped spillways. The writer would like to add some information on energy dissipation calculations of nappe flow and discuss the comparison between the rate of energy dissipation with nappe flow and skimming flow. It will be shown that, in fact, more flow energy is dissipated with a skimming flow regime (fig. A-2). ENERGY DISSIPATION IN NAPPE FLOW REGIME In a nappe flow regime, the total head loss on the spillway ∆E equals the difference between the maximum head available Eo and the residual head at the spillway toe. For an un-gated spillway (fig. 1), the writer (CHANSON 1993) showed that it yields: ∆