Characterization of Structural Properties in High Reynolds Hydraulic Jump Based on CFD and Physical Modeling Approaches

Abstract

A classical hydraulic jump of Fr1=6 and Re1= 210,000 was characterized using the Computational Flu id Dynamics (CFD) codes OpenFOAM and FLOW-3D, whose performance was assessed. The results were compared to experimental data from a physical model designed for the purpose. The most relevant hydraulic jump characteristics were investigated, including hydraulic jump efficiency, roller lengt h , free surface profile, distributions of velocity and pressure and fluctuating variables. The model outcome was also compared to previous results from the literature. It was found that both CFD cod es rep resent wit h high accuracy the hydraulic jump surface profile, roller length, efficiency and sequent depths ratio, consistently with previous research. Some significant differences were found between b ot h CFD co d es regarding velocity distributions and pressure fluctuations , although in general results are in good agreement with experimental and bibliographical observations. This makes models of these characteristics suitable for engineering applications involving design and optimization of energy dissipation devices.

Pressure Fluctuations in the Spatial Hydraulic Jump in Stilling Basins with Different Expansion Ratio

“…Beyond that, in the range 2.5 < X < 8, the average pressure shows an exponential trend (zone 2), and for X ≥ 8 (zone 3) the average pressure trend stabilizes and approaches the asymptotic range. This pattern is similar to that observed in free surface profiles in the hydraulic jumps, which suggests that, despite the large kinetic energy causing violent pressure fluctuations, the average pressure profile is also hydrostatic, in agreement with Macian-Perez et al [36]. In expansion ratios of 0.6 and 0.4, and also the case without any expansion (a = 1) the average pressure becomes particularly constant in zone 3.…”

Investigation of a Negative Step Effect on Stilling Basin by Using CFD

“…In the present numerical simulations, to determine the turbulent viscosity in Equation (6), the RNG k- ε turbulence model, based on the Boussinesq eddy-viscosity assumption, was used. The RNG k- ε turbulence model usually provides better results when simulating swirling flows relative to the standard k- ε model [ 21 , 22 ]. The RNG k- ε turbulence model expresses the turbulent viscosity in terms of the turbulent kinetic energy k and the turbulent kinetic energy dissipation rate ε as follows [ 23 ]: where is the turbulence constant, .…”

Study of a Hydraulic Jump in an Asymmetric Trapezoidal Channel with Different Sluice Gates

“…The hydraulic jump has been defined in several studies. For example, Sinniger et al defined the hydraulic jump in free surface flow as a sudden transition from supercritical to subcritical flow [4], characterized by a important turbulence, intense air entrainment and signifcant fuctuations in the velocity and pressure felds [5]. These turbulences cause a significant loss of energy [6], which becomes the operating principle of all water flow energy dissipators.…”