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This paper presents an experimental study on the dynamic response of square footings under effect of dynamic load comes from adjacent footing called the (source of vibration (which is excited by a known vibration source placed on the top of it, the objective is to study the effect of dynamic motion of the source of vibration on a nearby footing, ca...
Citations
The present research used a combination of experimental and numerical methods to investigate energy dissipation blocks of different heights placed downstream of a sluice gate in an open channel flow. Numerical model simulations were performed using a 3D computational fluid dynamics (CFD) technique, using the Reynolds-averaged Navier-Stokes (RANS) equations with the volume of fluid (VOF) and k-ε turbulence models. The accuracy of the numerical model and the grid sensitivity was assessed according to a recommended procedure in the literature. Different hydraulic and geometry conditions were investigated to understand the energy dissipation behaviour of the blocks. The hydrodynamic effects of different block spacings, heights and configurations were analysed by means of CFD simulations. The results show that the variable size blocks have a high energy dissipation efficiency in sluice gate flows, particularly at high Froude numbers. The energy dissipation efficiency of the blocks downstream of a sluice gate can reach up to 55% for high discharges (Q = 35 L/s). Interestingly, the energy dissipation performance of small gate openings exceeds that of large gate openings, reaching a peak efficiency of 40% for the same discharge. In addition, the block spacing has a minimal effect on the energy dissipation, while smaller block spacing results in a smoother water surface profile.
Introduction
The forced hydraulic jump characteristics were studied numerically using Flow-3D software. Rectangular and semi-cylindrical shape slices were used as obstacles with different arrangements in the stilling basin to dissipate the excess kinetic energy.
Methods
Each shape type was tested under five values of discharges (60, 80, 100, 120, and 160 l s⁻¹). The numerical results showed that the obstacles act as good energy dissipators, which decrease the hydraulic jump length and the length of the stilling basin as a result. The best case is installing three semi-cylindrical slices in the stilling basin, and energy dissipation ratios range from 48% to 63%, with an average difference of 14% from the values of classical hydraulic jumps, according to discharge values.
Results
It should be noted that the semi-cylindrical slices have better performance on energy dissipation ratios than rectangular slices, which indicates concave surface models cause the flow to change its direction, and this leads to a stable hydraulic condition.
Conclusion
Results of this work can be applied to a prototype by fixing three semi-cylindrical slices in the stilling basin at relative distances of 0.2, 0.5, and 0.8 from the end of the spillway, and this lead to maximize energy dissipation rates.
Energy dissipation is a crucial issue relating to the safety of the hydraulic structure. When water flows in high velocity, such structures have the harmful effect of converting the potential energy gained in the upstream side to kinetic energy in the downstream side. This energy must be dissipated shortly and safely as near as possible to the head structure to avoid its destructive effect. Baffle block is one of the efficient appurtenances that have a capacity in reducing the flow momentum that will decrease the flow velocity. Using baffle block is the main technique for accelerating the hydraulic jump formation and dissipating a great amount of the residual harmful kinetic energy occurring at the downstream of the spillway, channel or stilling basin. This paper reviews the experimental studies that have been done by previous researchers concerning the existence of the baffle block in the open channel and stilling basin.
