ABSTRACT
The transition from supercritical to subcritical flow in a smooth sloping channel with a horizontal downstream channel portion includes a large recirculating flow for a large channel slope and a large downstream depth. The reduction of a wide reverse-flow region is significant for designing stilling basins downstream of weirs and dams. Unfortunately, a method for reducing this wide reverse-flow region has not yet been developed. In this paper, a method for reducing a wide reverse-flow region that exists due to stepped channels is proposed. For a large channel slope and a large downstream depth, a plunging flow with a short reverse flow-region is formed by using stepped channels, and the main-flow velocity decays within a short distance. Further, the effect of a stepped channel on the reduction of the reverse-flow region was analyzed by comparing with the reverse-flow region in smooth sloping channels.
