Three dimensional and energy dissipation studies of hydraulic jumps

The velocity field of a three dimensional submerged hydraulic jump at a sudden horizontal expansion was investigated. The study has indicated that the jump consisted of a central jet-like flow, close to the channel bottom, surrounded by vertical and horizontal circulations (rollers). The circulation was predominantly in vertical planes in the channel central region of the flow and in horizontal planes close to the walls. Vertical and horizontal profiles of stream-wise velocity characterized the 3D roller with two length-scales. The strength of the roller was stronger close to the walls than at the centerline of the jump.;A novel perforated sill, applied as an appurtenance in a stilling basin to control free and submerged hydraulic jumps, was introduced. The perforated sill showed a depth reduction capability comparable to a solid sill. Also the perforated sill had many advantages over the solid sill, including shorter basin length, more stable flow, less scour, higher energy loss, self cleaning ability and less drag force.;A study of spatial submerged jump in symmetric and asymmetric abrupt expansions with and without solid sills in the basin was carried out. The study has indicated that the sequent depth was not significantly affected by asymmetry. The energy dissipation efficiency for the symmetric and asymmetric expansions with and without sill was found to depend mainly on the inlet Froude number. Using a sill in the basin allowed the flow to reach stability at smaller tail water depth compared to the no sill basin. Basin length for spatial submerged jump using a solid sill was found to be less than the corresponding length for no sill basin. Basin length increased with degree of asymmetry, suggesting the need for more bed protection for asymmetric stilling basins. Basin length for different cases was defined using empirical equations.;Degree of symmetry for an asymmetric spatial submerged hydraulic jump was investigated with a fuzzy model. The model provided linguistic expressions for the degree of symmetry that would help design a hydraulic jump basin when asymmetric jumps are anticipated. Agreement with experimental data has indicated that the fuzzy model has captured the dynamic behaviour of the spatial hydraulic jump.;Keywords. hydraulic jumps, spatial jumps, basin length, scour, drag force, asymmetric jumps, forced jump, solid sill, fuzzy algorithm, ADV.