Turbulent drag reduction in dam-break flows

Jánosi, Imre M.; Jan, Dominique; Szabó, Katalin Zsuzsanna; Tél, Tamás

doi:10.1007/s00348-004-0804-4

Cited by 147 publications

(91 citation statements)

References 35 publications

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“…As the hydraulic bore advances in the test channel, the still water layer resists to its propagation. This flow resistance and the resulting decrease in the bore-front velocity are well documented in the literature (Jánosi et al, 2004;Leal et al, 2006), even for h d of few millimeters. It is believed that the momentum transfer from the advancing bore-front to the downstream still water layer generates additional turbulence resulting in considerable air entrainment.…”

Section: Nistor Et Al (2010)supporting

confidence: 67%

Numerical Modeling of Tsunami-Induced Hydrodynamic Forces on Onshore Structures Using SPH

St-Germain

Nistor

Townsend

2012

Int. Conf. Coastal. Eng.

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In this paper, the simulation of the violent impact of tsunami-like bores with a square column is performed using a single-phase, weakly compressible three-dimensional Smoothed Particle Hydrodynamics (SPH) model. In order to avoid large fluctuations in the pressure field and to obtain accurate simulations of the hydrodynamic forces, a Riemann solver-based formulation of the SPH method is utilized. Large-scale physical experiments conducted by the authors are reproduced using the numerical model. Time-histories of the water surface elevation as well as timehistories of the pressure distribution and net total force acting on the column are successfully compared. As observed in previous breaking wave impact studies, results show that the magnitude and duration of the impulsive force at initial bore impact depend on the degree of entrapped air in the bore-front. Although ensuring a stable pressure field, the Riemann solver-based SPH scheme is believed to induce excessive numerical diffusion, as sudden and large water surface deformations, such as splashing at initial bore impact, are marginally reproduced. To investigate this particular issue, the small-scale physical experiment of Kleefsman et al. (2005) is also considered and modeled.

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Section: Nistor Et Al (2010)supporting

confidence: 67%

Numerical Modeling of Tsunami-Induced Hydrodynamic Forces on Onshore Structures Using SPH

St-Germain

Nistor

Townsend

2012

Int. Conf. Coastal. Eng.

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“…The case of a collapsing water column has been used in SPH studies [64,65], therefore it is utilised here to validate the implemented SPH model. Besides the validation of SPH model, the effect of different smoothing length, , and , is also examined.…”

Section: Sph Simulation Of Dam Break Test With Different Smoothing Lementioning

confidence: 99%

A coupled SPH-DEM model for fluid-structure interaction problems with free-surface flow and structural failure

Yang

Wright

2016

Computers & Structures

128

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“…Those studies gave details on the unsteady free surface characteristics based on the Froude number (II.3) or the dimensionless water elevation (for example, the ratio of water elevation d b /d 0 ). The characteristics include the bore celerity, the conjugated depth, the wave length and the amplitude of the secondary undulations (Benet and Cunge, 1971;Chanson, 2010a;Favre, 1935;Gualtieri and Chanson, 2012;Jánosi et al, 2004;Marche et al, 1995;Treske, 1994). Most studies tested several flow configurations, ranging from undular to breaking bores, thus giving an indication on the flow conditions leading to the formation of a breaking roller on the first undulations.…”

Section: Ii4 Experimental Studies Of Positive Surgesmentioning

confidence: 99%

Effects of tidal bores on turbulent mixing: a numerical and physical study in positive surges

Simon

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Tidal bores are positive surges created by the flooding of tides inside estuaries and rivers. They propagate upstream in an estuary sometimes as several metre high waves. Tidal bores are fascinating phenomenon with some impact on the wildlife, the mixing and re-suspension of sediments, and river constructions. Field studies remain challenging due to the violent nature of some bores. Herein, the hydrodynamics of tidal bores was investigated in a complementary study with experimental measurements and numerical simulations of idealised models of tidal bores. While laboratory experiments offer an accurate way to measure the flow properties, numerical simulations provide rather detailed information on the hydrodynamics of bores. These simulations require detailed experimental data to accurately replicate the experiments and validate the numerical methods.Investigations were conducted at the University of Queensland in a large rectangular channel partially covered by a fixed gravel bed. The steady flow condition properties were investigated using a Pitot tube and acoustic Doppler velocimeters (ADVs). The unsteady flow conditions were obtained by the fast closure of a downstream gate, which led to an upstream propagating bore. Free surface characteristics were studied for several types of bores, from undular to breaking. Those measurements showed large free surface fluctuations during the bore passage in agreement with earlier findings. Velocity measurements were conducted at high frequency (200 Hz). In breaking bores, the ensemble averaged data exhibited large velocity reversals near the bed beneath the bore front and in its wake, whereas, in undular bores, a lesser deceleration was observed. The vertical velocity data trend closely followed the water depth time derivative for both breaking and undular bores. Overall, the velocity measurements displayed large velocity fluctuations during the passage of the bore which were believed to induce strong turbulent mixing. The turbulence was further investigated by a two point correlation technique to estimate both turbulent integral time and length scales. The turbulent integral length scales values were similar in the steady and unsteady flows, whereas the turbulent time scales were larger in the unsteady flow. The experiments were limited by the instrumentation since the ADV systems interacted with each other and lacked accuracy for measurements performed in the near vicinity of physical boundaries.A numerical investigation was then performed using the computational fluid dynamics (CFD) ii code Thétis developed in the I2M laboratory of the Université de Bordeaux. Numerical simulations reproduced experiments performed in laboratory prior to this study (Chanson, 2010a,b). The fluid was modelled by the Navier-Stokes equations in their incompressible two-phase form. The turbulence model used a large eddy simulation and the interface air-water was tracked by using a volume of fluid model. Two dimensional and three dimensional simulations were performed to study the comp...

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Turbulent drag reduction in dam-break flows

Cited by 147 publications

References 35 publications

Numerical Modeling of Tsunami-Induced Hydrodynamic Forces on Onshore Structures Using SPH

Numerical Modeling of Tsunami-Induced Hydrodynamic Forces on Onshore Structures Using SPH

A coupled SPH-DEM model for fluid-structure interaction problems with free-surface flow and structural failure

Effects of tidal bores on turbulent mixing: a numerical and physical study in positive surges

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