Effect of oscillatory boundary layer on hydrodynamic forces on pipelines

Guoqiang Tang, Liang Cheng, Lin Lu, Yunfei Teng, Ming Zhao, Hongwei An

Research output: Contribution to journalArticle

Abstract

Numerical simulations were carried out to investigate hydrodynamic forces on submarine pipelines in oscillatory flows, with a focus on the conditions under which the pipeline diameter D is of a similar order of magnitude to the boundary-layer thickness δ i.e., δ/D ∼ O(1). Two-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with shear stress transport (SST) k-ω turbulence closure were solved using a Petrov–Galerkin finite element method (PG-FEM). The effects of the seabed roughness ks/D and the Keulegan-Carpenter number KC = UmT/D on the hydrodynamic force coefficients were investigated, where ks is the Nikuradse's equivalent roughness, T is the period of oscillatory flow and Um is the amplitude of the oscillatory velocity. The diameter of the submarine pipeline is fixed at D = 0.1 m. The Reynolds number, defined as Re = UmD/υ (where ν is the kinetic fluid viscosity), ranges from 1 × 104 to 4.5 × 104. The numerical results show that the boundary-layer thickness increases with ks. Hydrodynamic force coefficients are significantly affected by δ/D in the range of δ/D ∼ O(1), while δ/D depends on ks/D and KC number. The negligence of velocity reductions in the wave boundary layer leads to overestimations of the submerged weight required for achieving on-bottom stability.

Original languageEnglish
Pages (from-to)114-123
Number of pages10
JournalCoastal Engineering
Volume140
DOIs
Publication statusPublished - 1 Oct 2018

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Submarine pipelines
Boundary layers
Hydrodynamics
Pipelines
Surface roughness
Navier Stokes equations
Shear stress
Reynolds number
Turbulence
Viscosity
Finite element method
Kinetics
Fluids
Computer simulation

Cite this

Tang, Guoqiang ; Cheng, Liang ; Lu, Lin ; Teng, Yunfei ; Zhao, Ming ; An, Hongwei. / Effect of oscillatory boundary layer on hydrodynamic forces on pipelines. In: Coastal Engineering. 2018 ; Vol. 140. pp. 114-123.
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Effect of oscillatory boundary layer on hydrodynamic forces on pipelines. / Tang, Guoqiang; Cheng, Liang; Lu, Lin; Teng, Yunfei; Zhao, Ming; An, Hongwei.

In: Coastal Engineering, Vol. 140, 01.10.2018, p. 114-123.

Research output: Contribution to journalArticle

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AU - Cheng, Liang

AU - Lu, Lin

AU - Teng, Yunfei

AU - Zhao, Ming

AU - An, Hongwei

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