Modelling sedimentation–consolidation in the framework of a one-dimensional two-phase flow model

Chauchat, Julien; Guillou, Sylvain; Bang, Damien Pham Van; Nguyen, Kim Dan

doi:10.1080/00221686.2013.768798

Cited by 35 publications

(30 citation statements)

References 40 publications

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“…The numerical schemes are Euler implicit for the time derivative, upwind for the advection terms and central difference for the diffusion terms. For additional informations on the numerical model, the reader is referred to Chauchat et al (2013) and Chauchat et al (2015).…”

Section: Eulerian-eulerian Modelmentioning

confidence: 99%

Dense granular flow rheology in turbulent bedload transport

2016

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The local granular rheology is investigated numerically in turbulent bedload transport. Considering spherical particles, steady uniform configurations are simulated using a coupled fluid-discrete-element model. The stress tensor is computed as a function of the depth for a series of simulations varying the Shields number, the specific density and the particle diameter. The results are analyzed in the framework of the µ(I) rheology and exhibit a collapse of both the shear to normal stress ratio and the solid volume fraction over a wide range of inertial numbers. Contrary to expectations, the effect of the interstitial fluid on the granular rheology is shown to be negligible, supporting recent work suggesting the absence of a clear transition between the free-fall and turbulent regime. In addition, data collapse is observed up to unexpectedly high inertial numbers I ∼ 2, challenging the existing conceptions and parametrization of the µ(I) rheology. Focusing upon bedload transport modelling, the results are pragmatically analyzed in the µ(I) framework in order to propose a granular rheology for bedload transport. The proposed rheology is tested using a 1D volume-averaged two-phase continuous model, and is shown to accurately reproduce the dense granular flow profiles and the sediment transport rate over a wide range of Shields numbers. The present contribution represents a step in the upscaling process from particle-scale simulations toward large-scale applications involving complex flow geometry.

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Section: Eulerian-eulerian Modelmentioning

confidence: 99%

Dense granular flow rheology in turbulent bedload transport

2016

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“…Numerous studies based on Gibson's theory simulated mud consolidation with fairly good skills (e.g. Winterwerp and Van Kesteren 2004;De Boer et al 2007;Thiebot et al 2011;Chauchat et al 2013); however, they rarely applied to mixed sediments. Some models considering mud-sand mixtures were proposed (e.g.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of mixed-sediment consolidation

2015

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Sediment transport modelling in estuarine environments, characterised by cohesive and non-cohesive sediment mixtures, has to consider a time variation of erodibility due to consolidation. Generally, validated by settling column experiments, mud consolidation is now fairly well simulated; however, numerical models still have difficulty to simulate accurately the sedimentation and consolidation of mixed sediments for a wide range of initial conditions. This is partly due to the difficulty to formulate the contribution of sand in the hindered settling regime when segregation does not clearly occur. Based on extensive settling experiments with mud-sand mixtures, the objective of this study was to improve the numerical modelling of mixed-sediment consolidation by focusing on segregation processes. We used constitutive relationships following the fractal theory associated with a new segregation formulation based on the relative mud concentration. Using specific sets of parameters calibrated for each testwith different initial sediment concentration and sand content-the model achieved excellent prediction skills for simulating sediment height evolutions and concentration vertical profiles. It highlighted the model capacity to simulate properly the segregation occurrence for mud-sand mixtures characterised by a wide range of initial conditions. Nevertheless, calibration parameters varied significantly, as the fractal number ranged from 2.64 to 2.77. This study investigated the relevance of using a common set of parameters, which is generally required for 3D sediment transport modelling. Simulations were less accurate but remained satisfactory in an operational approach. Finally, a specific formulation for natural estuarine environments was proposed, simulating correctly the sedimentation-consolidation processes of mud-sand mixtures through 3D sediment transport modelling.

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“…Code availability. The code is distributed under a GNU General Public License v2.0 (GNU GPL v2.0) and is available at https: //github.com/SedFoam/sedfoam/releases/tag/v2.0 or on Zenodo at https://zenodo.org/record/836643#.Wc47Yoo690s with the following DOI https://doi.org/10.5281/zenodo.836643 (Chauchat et al, 2017). The source code has been compiled and extensively tested with OpenFOAM 2.4.0.…”

Section: Discussionmentioning

confidence: 99%

Answer to SC1

Chauchat¹

2017

Preprint

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In this paper, a three-dimensional two-phase flow solver, SedFoam-2.0, is presented for sediment transport applications. The solver is extended from twoPhaseEulerFoam available in the 2.1.0 release of the open-source CFD (computational fluid dynamics) toolbox OpenFOAM. In this approach the sediment phase is modeled as a continuum, and constitutive laws have to be prescribed for the sediment stresses. In the proposed solver, two different intergranular stress models are implemented: the kinetic theory of granular flows and the dense granular flow rheology µ(I). For the fluid stress, laminar or turbulent flow regimes can be simulated and three different turbulence models are available for sediment transport: a simple mixing length model (one-dimensional configuration only), a k − ε, and a k − ω model. The numerical implementation is demonstrated on four test cases: sedimentation of suspended particles, laminar bed load, sheet flow, and scour at an apron. These test cases illustrate the capabilities of SedFoam-2.0 to deal with complex turbulent sediment transport problems with different combinations of intergranular stress and turbulence models.

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Modelling sedimentation–consolidation in the framework of a one-dimensional two-phase flow model

Cited by 35 publications

References 40 publications

Dense granular flow rheology in turbulent bedload transport

Dense granular flow rheology in turbulent bedload transport

Numerical modelling of mixed-sediment consolidation

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