Abstract
The skimming flows in stepped spillways are classified into the nonaerated and aerated regions. For a large discharge and/or a small dam height, the nonaerated region may occupy a large portion of the flow in stepped spillways. However, most experimental studies for stepped channels have focused on aerated skimming flows, and the characteristics of nonaerated skimming flows have not yet been clarified. In this paper, empirical equations for the estimation of the flow depth and the boundary layer thickness are proposed in the nonaerated flow region. The velocity profile and the boundary layer development are shown, and the relative specific energy E/dc (dc=critical flow depth, E=specific energy) with the energy coefficient is obtained along the stepped channels. The effect of the channel slope and the relative step height on E/dc is clarified on the basis of the boundary layer development.
