Longitudinal Change in Flow Structures and Energy Loss of Free Jumps and Submerged Jumps of Flows over an Embankment-type Weir

This study numerically investigates the longitudinal changes in the flow structures and energy loss of the free jumps and the submerged jumps. The hydraulic jumps from flows over an embankment-type weir are considered. For the numerical simulations, the 2D Unsteady Reynolds-Averaged Navier-Stokes equations are solved using the k–ω SST turbulence model. Flow structures and their longitudinal changes are compared with the available experimental data, showing moderate agreement. The simulation results indicate that the decaying patterns of the flow structures for the free jump are roughly similar to those for the submerged jump. The decaying rate decreases with increasing submergence ratio, in which process the adverse pressure gradient plays a key role. It is also confirmed that the loss of the kinetic energy increases with decreasing submergence ratio. For both free jump and submerged jump, the process of dissipating the kinetic energy terminates within the developed zone, with the decaying process of the flow structure unfinished.