Numerical Simulations of the Flow Field of a Submerged Hydraulic Jump over Triangular Macroroughnesses

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In the stepped spillway, the steps, by providing an artificial roughening bed, dissipate the flow of energy more than other types of spillways, so the construction costs for stilling basin are reduced. However, what is important in this type of spillway is increasing the effectiveness of steps in the rate of energy dissipation. The present study deals with experimental and numerical simulations regarding the influence of geometric appendance elements on the steps and its impact on the energy dissipation performances, flow patterns properties, turbulent kinetic energy, flow resistance and the Darcy roughness. The localization of inception point of air entrainment is also assessed. To this aim, different configurations are taken into account. The computational procedure is validated with experimental results and then used to test the hydraulic behavior of different geometric configurations. The results showed that the appendance elements on the steps increased the turbulent kinetic energy (TKE) values and Darcy–Weisbach friction and the energy dissipation increased significantly. By reducing the height of the elements, energy dissipation and the TKE value increase more significantly. With the appendance elements on step, the air entrainment inception locations a positioning further upstream than the flat step stepped spillway.

Section: Flow Patternmentioning

confidence: 88%

“…Turbulent kinetic energy (TKE) is resulting in the spillways due to mean velocity gradients [51] and is an important index to reflect the energy loss between two sections of the flow. TKE is characterized by measuring the root-mean-square of velocity fluctuations [56].…”

Section: Turbulent Kinetic Energy (Tke)mentioning

confidence: 99%

Experimental and Numerical Study of the Effects of Geometric Appendance Elements on Energy Dissipation over Stepped Spillway

Ghaderi

Abbasi

2021

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“…A turbulence model is needed for additional modeling of the nonlinear Reynolds stress term. Some numerical studies have proposed the Reynolds-Averaged Navier-Stokes (RANS)-based k-omega and the Renormalization Group (RNG) k-ε [28][29][30][31][32][33][34][35][36][37] and LES (large eddy simulation) models [38][39][40] for the scouring problem. The LES turbulence model was used to perform computation of fluid dynamics (CFD).…”

Section: Turbulence Modelmentioning

confidence: 99%

“…These piers are called hydrodynamic piers, which have sharp noses that coordinate with the flow streamlines and follow the equations of hydrodynamic flow conditions. Based on Ghaderi and Abbasi's [32] study, keen and round nose piers reduce the bed shear stress value more than a circular pier does. According to the recommendations of Ataei-Ashtiani and Beheshti [2], bridge piers with a length of 13.5 cm and a diameter of 9 cm were placed at intervals of 7.6 cm.…”

Section: Simulation Of Local Scouring Around the Hydrodynamic Pile Groupmentioning

confidence: 99%

Investigation of Local Scouring around Hydrodynamic and Circular Pile Groups under the Influence of River Material Harvesting Pits

Daneshfaraz

Ghaderi

Sattariyan

et al. 2021

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Mining activities can endanger the stability of hydraulic structures. Numerical modeling of local scouring around hydrodynamic and circular bridge pile groups, due to the action of clear water conditions via non-cohesive sediment, was performed using a computational fluid dynamics (CFD) model, a large eddy simulation (LES) turbulence model, and a van Rijn sedimentary model with FLOW-3D software. The pile groups were positioned upstream and downstream of a sand mining pit. The results showed that the scour depth around the downstream pile group was greater than that of the upstream one. Using hydrodynamic piers reduced the scour depth upstream of all piers and the material harvesting pit. The maximum reduction in scour depth was observed in front of the fifth pier, with a 29% reduction in scour depth. Additionally, for all models, as the material harvesting pit was moved downstream, the downstream turbulence was enhanced and stronger flow reversal and horseshoe vortices were detected in from of the downstream pile group. The flow patterns around the pile group showed that the presence of hydrodynamic piers in the upstream pile group leads to a decrease in the maximum flow velocity, whereas, when such piers were positioned in the downstream pile group, the velocity increases.

“…The objective of paper [10] was to numerically investigate the effects of triangular macro-roughness on the characteristics of submerged jump, e.g., the longitudinal profile of streamlines, flow patterns in the cavity region, horizontal velocity profiles, streamwise velocity distribution, thickness of the inner layer, bed shear stress coefficient, turbulent kinetic energy (TKE), and energy loss. Different macroroughness arrangements and various inlet Froude numbers (1.7 < Fr < 9.3) were considered.…”

mentioning

confidence: 99%

Hydraulic Dynamic Calculation and Simulation

Aricò

2021

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