Standard

Ill-posedness in modeling mixed sediment river morphodynamics. / Chavarrias Borras, V.; Stecca, Guglielmo; Blom, Astrid.

In: Advances in Water Resources, Vol. 114, 01.04.2018, p. 219-235.

Research output: Contribution to journalArticleScientificpeer-review

Harvard

APA

Vancouver

Author

Chavarrias Borras, V. ; Stecca, Guglielmo ; Blom, Astrid. / Ill-posedness in modeling mixed sediment river morphodynamics. In: Advances in Water Resources. 2018 ; Vol. 114. pp. 219-235.

BibTeX

@article{030c105621284bbfa57b0cf0fc3f6b30,
title = "Ill-posedness in modeling mixed sediment river morphodynamics",
abstract = "In this paper we analyze the Hirano active layer model used in mixed sediment river morphodynamics concerning its ill-posedness. Ill-posedness causes the solution to be unstable to short-wave perturbations. This implies that the solution presents spurious oscillations, the amplitude of which depends on the domain discretization. Ill-posedness not only produces physically unrealistic results but may also cause failure of numerical simulations. By considering a two-fraction sediment mixture we obtain analytical expressions for the mathematical characterization of the model. Using these we show that the ill-posed domain is larger than what was found in previous analyses, not only comprising cases of bed degradation into a substrate finer than the active layer but also in aggradational cases. Furthermore, by analyzing a three-fraction model we observe ill-posedness under conditions of bed degradation into a coarse substrate. We observe that oscillations in the numerical solution of ill-posed simulations grow until the model becomes well-posed, as the spurious mixing of the active layer sediment and substrate sediment acts as a regularization mechanism. Finally we conduct an eigenstructure analysis of a simplified vertically continuous model for mixed sediment for which we show that ill-posedness occurs in a wider range of conditions than the active layer model.",
keywords = "Ill-posedness, Mixed sediment, River morphodynamics",
author = "{Chavarrias Borras}, V. and Guglielmo Stecca and Astrid Blom",
year = "2018",
month = "4",
day = "1",
doi = "10.1016/j.advwatres.2018.02.011",
language = "English",
volume = "114",
pages = "219--235",
journal = "Advances in Water Resources",
issn = "0309-1708",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Ill-posedness in modeling mixed sediment river morphodynamics

AU - Chavarrias Borras, V.

AU - Stecca, Guglielmo

AU - Blom, Astrid

PY - 2018/4/1

Y1 - 2018/4/1

N2 - In this paper we analyze the Hirano active layer model used in mixed sediment river morphodynamics concerning its ill-posedness. Ill-posedness causes the solution to be unstable to short-wave perturbations. This implies that the solution presents spurious oscillations, the amplitude of which depends on the domain discretization. Ill-posedness not only produces physically unrealistic results but may also cause failure of numerical simulations. By considering a two-fraction sediment mixture we obtain analytical expressions for the mathematical characterization of the model. Using these we show that the ill-posed domain is larger than what was found in previous analyses, not only comprising cases of bed degradation into a substrate finer than the active layer but also in aggradational cases. Furthermore, by analyzing a three-fraction model we observe ill-posedness under conditions of bed degradation into a coarse substrate. We observe that oscillations in the numerical solution of ill-posed simulations grow until the model becomes well-posed, as the spurious mixing of the active layer sediment and substrate sediment acts as a regularization mechanism. Finally we conduct an eigenstructure analysis of a simplified vertically continuous model for mixed sediment for which we show that ill-posedness occurs in a wider range of conditions than the active layer model.

AB - In this paper we analyze the Hirano active layer model used in mixed sediment river morphodynamics concerning its ill-posedness. Ill-posedness causes the solution to be unstable to short-wave perturbations. This implies that the solution presents spurious oscillations, the amplitude of which depends on the domain discretization. Ill-posedness not only produces physically unrealistic results but may also cause failure of numerical simulations. By considering a two-fraction sediment mixture we obtain analytical expressions for the mathematical characterization of the model. Using these we show that the ill-posed domain is larger than what was found in previous analyses, not only comprising cases of bed degradation into a substrate finer than the active layer but also in aggradational cases. Furthermore, by analyzing a three-fraction model we observe ill-posedness under conditions of bed degradation into a coarse substrate. We observe that oscillations in the numerical solution of ill-posed simulations grow until the model becomes well-posed, as the spurious mixing of the active layer sediment and substrate sediment acts as a regularization mechanism. Finally we conduct an eigenstructure analysis of a simplified vertically continuous model for mixed sediment for which we show that ill-posedness occurs in a wider range of conditions than the active layer model.

KW - Ill-posedness

KW - Mixed sediment

KW - River morphodynamics

UR - http://www.scopus.com/inward/record.url?scp=85042462161&partnerID=8YFLogxK

UR - http://resolver.tudelft.nl/uuid:030c1056-2128-4bbf-a57b-0cf0fc3f6b30

U2 - 10.1016/j.advwatres.2018.02.011

DO - 10.1016/j.advwatres.2018.02.011

M3 - Article

VL - 114

SP - 219

EP - 235

JO - Advances in Water Resources

T2 - Advances in Water Resources

JF - Advances in Water Resources

SN - 0309-1708

ER -

ID: 42059099