Numerical simulation of wave-induced scour and backfilling processes beneath submarine pipelines

2014-12-01
Fuhrman, David R
Baykal, Cüneyt
Sumer, B Mutlu
Jacobsen, Niels G
Fredsoe, Jorgen
A fully-coupled hydrodynamic/morphodynamic numerical model is presented and utilized for the simulation of wave-induced scour and backfilling processes beneath submarine pipelines. The model is based on solutions to Reynolds-averaged Navier-Stokes equations, coupled with k - omega turbulence closure, with additional bed and suspended load descriptions forming the basis for sea bed morphology. The morphological evolution is updated continuously, rather than being based e.g. on period- or other time-averaging techniques. Simulations involving wave-induced scour over the range of Keulegan-Carpenter number 5.6 <= KC <= 30 demonstrate reasonable match with previous experiments, both in terms of the equilibrium scour depth as well as the scour time scale. Waveinduced backfilling processes are additionally studied by subjecting initial conditions taken from scour simulations with larger KC to new wave climates characterized by lower KC values. The simulations considered demonstrate the ability of the model to predict backfilling toward expected equilibrium scour depths based on the new wave climate, in line with experimental expectations. The simulated backffiling process is characterized by two stages: (1) An initial re-distribution phase involving re-organization of sediments in the immediate vicinity of the pipeline, potentially followed by (2) a more lengthy backfilling evolution toward equilibrium scour depth. The simulated backfilling time scales are of the same order of magnitude as in experiments, though the multi-stage process complicates a more systematic characterization. The simulated sequences of scour and backfilling achieved within the present work are estimated to represent temporal durations of up to approximately 12 h at full practical scales.
COASTAL ENGINEERING

Suggestions

Numerical calculation of backfilling of scour holes
Sumer, B Mutlu; Baykal, Cüneyt; Fuhrman, David R; Jacobsen, Niels G; Fredsoe, Jorgen (2014-12-04)
A fully-coupled hydrodynamic and morphologic CFD model is presented for simulating backfilling processes around structures. The hydrodynamic model is based on Reynolds-averaged Navier-Stokes equations, coupled with two-equation k-ω turbulence closure. The sediment transport model consists of separate bed and suspended load descriptions, the latter based on a turbulent diffusion equation coupled with a reference concentration function near the sea bed boundary. Bed morphology is based on the sediment continu...
Computational investigation of rotorcraft avionics bay cooling system
Akın, Altuğ; Kahveci, Harika Senem; Department of Aerospace Engineering (2019)
Computational investigation of a rotorcraft avionics bay cooling system is performed. Within the introduced system, the ambient air is supplied to the avionics-bay by a fan and exhausted back into the ambient after cooling the equipment inside. Depending on the fan and exhaust locations, hot zones may form around some of the equipment. The fan must provide a sufficiently high mass flow rate to keep the temperatures of the avionics equipment below the limits, while avoiding excessive amount of cooling to red...
Numerical Modeling of Backfilling Process around Monopiles
Baykal, Cüneyt; Fuhrman, David R; Jacobsen, Niels G; Fredsoe, Jorgen (2014-06-20)
This study presents a three-dimensional (3D) numerical modeling study on the backfilling process around monopiles. The numerical model utilized in the study is based on that given by Jacobsen (2011). It is composed of two main modules. The first module is the hydrodynamic model where the fluid flow conditions around the structure and near the bed are solved. The second module is the morphologic model where the sediment transport rates over the bed and around the structure are obtained and used in updating b...
Comparison of turbulence model and wall function couplings for simulating scour
Şentürk, Barış Ufuk; Baykal, Cüneyt; Department of Civil Engineering (2022-1-19)
In this study, the scouring of bed material at the rear side of a rubble mound coastal revetment due to the overtopping of solitary-like waves is numerically studied using a coupled hydrodynamic and morphological computational fluid dynamics model. The major purpose of this thesis study is to investigate the performances of different turbulence model and wall function couplings on the hydrodynamic and morphological results. In the first part of this study, hydrodynamic simulations are performed, and the res...
Simulation of water exchange in enclosed water bodies
Ozhan, E; Balas, L (2003-01-01)
A 0-D (box type) mathematical flushing model and a three-dimensional baroclinic numerical model have been presented that are used to simulate transport processes in coastal waters. The numerical model consists of hydrodynamic, transport and turbulence model components. In the hydrodynamic model component, the Navier-Stokes equations are solved with the Boussinesq approximation. The transport model component consists of the pollutant transport model and the water temperature and salinity transport models. In...
Citation Formats
D. R. Fuhrman, C. Baykal, B. M. Sumer, N. G. Jacobsen, and J. Fredsoe, “Numerical simulation of wave-induced scour and backfilling processes beneath submarine pipelines,” COASTAL ENGINEERING, pp. 10–22, 2014, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41511.