CFD investigations of scour beneath a submarine pipeline with the effect of upward seepage

Yuzhu Li, Muk Chen Ong*, David R. Fuhrman

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

A numerical model of scour beneath subsea structures considering the effect of upward seepage in the seabed is proposed. A small seepage can cause significant changes to the hydrodynamic force on the bed surface and stability of bed particles, which can further affect the sediment transport processes and scour patterns around subsea structures. The present model is developed based on a fully-coupled hydrodynamic and morphologic sediment transport model. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved together with the k−ω turbulence closure. In the presence of seepage, the bed friction velocity, the bed shear stress, and the bed load transport rate will be changed as compared to conditions without seepage. The sediment particle stability is also affected and the critical Shields parameter is changed. In the presence of upward seepage forces, the repose angle of the sediment is also reduced. The present model is validated against existing experiments in terms of streamwise flow velocity distribution subjected to upward seepage. The fully-coupled hydrodynamic and morphologic model is validated against existing experiments of scour beneath a pipeline in the live-bed regime and clear-water regime, respectively. The validated model is then applied to investigate the scour development beneath a submarine pipeline subjected to different upward hydraulic gradients. It is found that the equilibrium scour width is increased with a large upward hydraulic gradient. The equilibrium scour depth stays in the range of 0.6–0.8 of the pipeline diameter for the live-bed cases. For the clear-water case, with a large upward hydraulic gradient, the equilibrium scour depth slightly decreases.
Original languageEnglish
Article number103624
JournalCoastal engineering
Volume156
Number of pages12
ISSN0378-3839
DOIs
Publication statusPublished - 2020

Bibliographical note

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Keywords

  • CFD
  • Numerical model
  • Submarine pipeline
  • Seepage
  • Scour

Cite this

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title = "CFD investigations of scour beneath a submarine pipeline with the effect of upward seepage",
abstract = "A numerical model of scour beneath subsea structures considering the effect of upward seepage in the seabed is proposed. A small seepage can cause significant changes to the hydrodynamic force on the bed surface and stability of bed particles, which can further affect the sediment transport processes and scour patterns around subsea structures. The present model is developed based on a fully-coupled hydrodynamic and morphologic sediment transport model. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved together with the k−ω turbulence closure. In the presence of seepage, the bed friction velocity, the bed shear stress, and the bed load transport rate will be changed as compared to conditions without seepage. The sediment particle stability is also affected and the critical Shields parameter is changed. In the presence of upward seepage forces, the repose angle of the sediment is also reduced. The present model is validated against existing experiments in terms of streamwise flow velocity distribution subjected to upward seepage. The fully-coupled hydrodynamic and morphologic model is validated against existing experiments of scour beneath a pipeline in the live-bed regime and clear-water regime, respectively. The validated model is then applied to investigate the scour development beneath a submarine pipeline subjected to different upward hydraulic gradients. It is found that the equilibrium scour width is increased with a large upward hydraulic gradient. The equilibrium scour depth stays in the range of 0.6–0.8 of the pipeline diameter for the live-bed cases. For the clear-water case, with a large upward hydraulic gradient, the equilibrium scour depth slightly decreases.",
keywords = "CFD, Numerical model, Submarine pipeline, Seepage, Scour",
author = "Yuzhu Li and Ong, {Muk Chen} and Fuhrman, {David R.}",
note = "This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).",
year = "2020",
doi = "10.1016/j.coastaleng.2019.103624",
language = "English",
volume = "156",
journal = "Coastal Engineering",
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}

CFD investigations of scour beneath a submarine pipeline with the effect of upward seepage. / Li, Yuzhu; Ong, Muk Chen; Fuhrman, David R.

In: Coastal engineering, Vol. 156, 103624, 2020.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - CFD investigations of scour beneath a submarine pipeline with the effect of upward seepage

AU - Li, Yuzhu

AU - Ong, Muk Chen

AU - Fuhrman, David R.

N1 - This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

PY - 2020

Y1 - 2020

N2 - A numerical model of scour beneath subsea structures considering the effect of upward seepage in the seabed is proposed. A small seepage can cause significant changes to the hydrodynamic force on the bed surface and stability of bed particles, which can further affect the sediment transport processes and scour patterns around subsea structures. The present model is developed based on a fully-coupled hydrodynamic and morphologic sediment transport model. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved together with the k−ω turbulence closure. In the presence of seepage, the bed friction velocity, the bed shear stress, and the bed load transport rate will be changed as compared to conditions without seepage. The sediment particle stability is also affected and the critical Shields parameter is changed. In the presence of upward seepage forces, the repose angle of the sediment is also reduced. The present model is validated against existing experiments in terms of streamwise flow velocity distribution subjected to upward seepage. The fully-coupled hydrodynamic and morphologic model is validated against existing experiments of scour beneath a pipeline in the live-bed regime and clear-water regime, respectively. The validated model is then applied to investigate the scour development beneath a submarine pipeline subjected to different upward hydraulic gradients. It is found that the equilibrium scour width is increased with a large upward hydraulic gradient. The equilibrium scour depth stays in the range of 0.6–0.8 of the pipeline diameter for the live-bed cases. For the clear-water case, with a large upward hydraulic gradient, the equilibrium scour depth slightly decreases.

AB - A numerical model of scour beneath subsea structures considering the effect of upward seepage in the seabed is proposed. A small seepage can cause significant changes to the hydrodynamic force on the bed surface and stability of bed particles, which can further affect the sediment transport processes and scour patterns around subsea structures. The present model is developed based on a fully-coupled hydrodynamic and morphologic sediment transport model. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved together with the k−ω turbulence closure. In the presence of seepage, the bed friction velocity, the bed shear stress, and the bed load transport rate will be changed as compared to conditions without seepage. The sediment particle stability is also affected and the critical Shields parameter is changed. In the presence of upward seepage forces, the repose angle of the sediment is also reduced. The present model is validated against existing experiments in terms of streamwise flow velocity distribution subjected to upward seepage. The fully-coupled hydrodynamic and morphologic model is validated against existing experiments of scour beneath a pipeline in the live-bed regime and clear-water regime, respectively. The validated model is then applied to investigate the scour development beneath a submarine pipeline subjected to different upward hydraulic gradients. It is found that the equilibrium scour width is increased with a large upward hydraulic gradient. The equilibrium scour depth stays in the range of 0.6–0.8 of the pipeline diameter for the live-bed cases. For the clear-water case, with a large upward hydraulic gradient, the equilibrium scour depth slightly decreases.

KW - CFD

KW - Numerical model

KW - Submarine pipeline

KW - Seepage

KW - Scour

U2 - 10.1016/j.coastaleng.2019.103624

DO - 10.1016/j.coastaleng.2019.103624

M3 - Journal article

VL - 156

JO - Coastal Engineering

JF - Coastal Engineering

SN - 0378-3839

M1 - 103624

ER -