Numerical Assessment of the Performance of Bed Water Jets in Submerged Hydraulic Jumps

Abstract

Submerged hydraulic jumps commonly occur downstream of irrigation structures. Submerged hydraulic jumps dissipate energy to some extent, and bed water jets can be employed as a means to increase their energy dissipation. In this study, submerged hydraulic jumps with and without bed water jets, with initial Froude numbers ranging between 2.2 and 6.06, were simulated using relative jet discharges ranging from 0% to 30% with respect to the main flow discharge. Computational fluid dynamics (CFD) modeling was applied to solve the equations for the conservation of the mass, momentum, and energy of the fluid flow. The volume of fluid (VOF) method was employed to compute the characteristics of the submerged jumps. In modeling the turbulence stresses, k-ω shear stress transport (SST) and Reynolds-averaged Navier-Stokes (RANS) equations were employed. The modeled velocity profiles agreed well with corresponding experimental measurements, proving the consistency of the computational results. Simulated results indicated that the bed water jets improved the efficiency of the submerged hydraulic jumps by up to 85.4% and reduced the submerged jump lengths by up to 59% compared to the nonjetted system.