The Equivalent Depth of Wave-Induced Scour Around Offshore Pipelines

2006 ◽  
Author(s):  
Mir Emad Mousavi ◽  
Abbas Yeganeh Bakhtiary ◽  
Nastaran Enshaei
Keyword(s):  
Deep Water ◽  
Numerical Models ◽  
Scour Depth ◽  
Offshore Pipelines ◽  
Equivalent Depth ◽  
Physical Experiments ◽  
Water Conditions ◽  
Installation Depth ◽  
New Equation ◽  
Wave Induced

Physical experiments have been conducted to study the scouring around a pipe over an erodible bed under waves motion. The results show that the depth of the wave-induced scour is reduced when the pipe is installed in a primary depth. It is also indicated that when the primary installation depth of the pipe, |e|, exceeds a specified depth, no scouring occurs underneath the pipe. This specific depth is called the Equivalent Depth of Wave-Induced scour, Se. The equivalent depth of wave-induced scour is estimated as a function of pipe diameter and the Keulegan Carpenter number. Also for prediction of the scour depth with respect to the primary installation depth of the pipe, a new equation is proposed. In addition, new equations are proposed for prediction of the scour width before the pipe is installed. The results and proposed equations are next simplified in the form of diagrams to be used in practice. The experiments cover small KC numbers (KC < 6) that represent deep water conditions. The results can be used either for the design purposes or for calibration of the numerical models.

The Equivalent Depth of Wave-Induced Scour Around Offshore Pipelines

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Mir Emad Mousavi ◽  
Abbas Yeganeh Bakhtiary ◽  
Nastaran Enshaei
Keyword(s):  
Deep Water ◽  
Wave Motion ◽  
Scour Depth ◽  
Offshore Pipelines ◽  
Equivalent Depth ◽  
Physical Experiments ◽  
Water Conditions ◽  
Installation Depth ◽  
New Equation ◽  
Wave Induced

Physical experiments have been conducted to study the scouring around a pipe over an erodible bed under wave motion. The results show that the depth of the wave-induced scour is reduced when the pipe is installed in a primary depth. It is also indicated that when the primary installation depth of the pipe, |e|, exceeds a specified depth, no scouring occurs underneath the pipe. This specific depth is called the equivalent depth of wave-induced scour, Se. The equivalent depth of wave-induced scour is estimated as a function of pipe diameter and the Keulegan–Carpenter number. With respect to the primary installation depth of the pipe, a new equation is suggested to predict the scour depth before installation of the pipe. And the scour width is predicted in two other new equations. The proposed equations are then simplified in the form of diagrams. The experiments cover small KC numbers (KC<6) that represent deep water conditions.

Time Scale of Scouring Around Submarine Pipelines Induced by Wave and Current

2006 ◽  
Author(s):  
Abbas Yeganeh Bakhtiary ◽  
Mir Emad Mousavi ◽  
Amin Tohidi Vahdat
Keyword(s):  
Time Scale ◽  
Total Duration ◽  
Experimental Results ◽  
Scour Depth ◽  
Duration Time ◽  
Physical Experiments ◽  
New Equation

Physical experiments have been conducted to explore the time scale of the wave- and current- induced local scouring around submarine pipelines as well as the development of the scour profile versus the elapsing time. The experimental results have been used to examine the recommended equations of Fredsoe et al. (1992) and/or to derive new equations for prediction of scour depth/width during the process with respect to the equilibrium scour properties. In addition, the total duration (time scale) of scouring is studied and a new equation is proposed for the case of current motion. The results of this equation are then simplified in the form of diagrams for estimation of the scouring duration in practice.

scholarly journals Meshfree Model for Wave-Seabed Interactions Around Offshore Pipelines

2019 ◽  
Vol 7 (4) ◽  
pp. 87 ◽  
Author(s):  
Xiao Wang ◽  
Dong-Sheng Jeng ◽  
Chia-Cheng Tsai
Keyword(s):  
Present Model ◽  
Numerical Models ◽  
Degree Of Saturation ◽  
Navier Stokes ◽  
Submarine Pipeline ◽  
Offshore Pipelines ◽  
Soil Response ◽  
Offshore Pipeline ◽  
Proposed Model ◽  
Wave Induced

The evaluation of the wave-induced seabed instability around a submarine pipeline is particularly important for coastal engineers involved in the design of pipelines protection. Unlike previous studies, a meshfree model is developed to investigate the wave-induced soil response in the vicinity of a submarine pipeline. In the present model, Reynolds-Averaged Navier-Stokes (RANS) equations are employed to simulate the wave loading, while Biot’s consolidation equations are adopted to investigate the wave-induced soil response. Momentary liquefaction around an offshore pipeline in a trench is examined. Validation of the present seabed model was conducted by comparing with the analytical solution, experimental data, and numerical models available in the literature, which demonstrates the capacity of the present model. Based on the newly proposed model, a parametric study is carried out to investigate the influence of soil properties and wave characteristics for the soil response around the pipeline. The numerical results conclude that the liquefaction depth at the bottom of the pipeline increases with increasing water period (T) and wave height (H), but decreases as backfilled depth ( H b ), degree of saturation ( S r ) and soil permeability (K) increase.

Variability in surface and deep water conditions in the nordic seas during the last interglacial period

1998 ◽  
Vol 17 (9-10) ◽  
pp. 963-985 ◽  
Author(s):  
Torben Fronval ◽  
Eystein Jansen ◽  
Haflidi Haflidason ◽  
Hans Petter Sejrup
Keyword(s):  
Deep Water ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Nordic Seas ◽  
Last Interglacial Period ◽  
Water Conditions

Wave action on currents with vorticity

1999 ◽  
Vol 386 ◽  
pp. 329-344 ◽  
Author(s):  
BENJAMIN S. WHITE
Keyword(s):  
Phase Shift ◽  
Deep Water ◽  
Current Velocity ◽  
Wave Action ◽  
Ray Theory ◽  
Wkb Method ◽  
Interaction Of Waves ◽  
New Equation ◽  
Spatially Varying

The interaction of waves on deep water with spatially varying currents may be described by a ray theory, with the wave amplitudes determined by the principle of conservation of wave action (CWA). However, all previous deep water derivations of CWA are restricted to the case of an irrotational current. In this paper, both the ray theory and CWA are derived by a WKB method without the assumption of irrotationality. Also derived is a new equation for a spatially varying phase shift which is not predicted by the usual ray theory, and which, in general, displaces the positions of the wave crests by a distance on the order of a wavelength. This phase shift, which is caused by variations of the current velocity with depth, vanishes in the irrotational case, and so is in accord with the irrotational theory.

An experimental and numerical study of the resonant flow between a hull and a wall

2021 ◽  
Vol 930 ◽  
Author(s):  
I.A. Milne ◽  
O. Kimmoun ◽  
J.M.R. Graham ◽  
B. Molin
Keyword(s):  
Vortex Shedding ◽  
Particle Image ◽  
Numerical Study ◽  
Numerical Models ◽  
Vertical Wall ◽  
Liquefied Natural Gas ◽  
Narrow Gap ◽  
Image Velocimetry ◽  
High Degree ◽  
Wave Induced

The wave-induced resonant flow in a narrow gap between a stationary hull and a vertical wall is studied experimentally and numerically. Vortex shedding from the sharp bilge edge of the hull gives rise to a quadratically damped free surface response in the gap, where the damping coefficient is approximately independent of wave steepness and frequency. Particle image velocimetry and direct numerical simulations were used to characterise the shedding dynamics and explore the influence of discretisation in the measurements and computations. Secondary separation was identified as a particular feature which occurred at the hull bilge in these gap flows. This can result in the generation of a system with multiple vortical regions and asymmetries between the inflow and outflow. The shedding dynamics was found to exhibit a high degree of invariance to the amplitude in the gap and the spanwise position of the barge. The new measurements and the evaluation of numerical models of varying fidelity can assist in informing offshore operations such as the side by side offloading from floating liquefied natural gas facilities.

scholarly journals Wave Climate at Shallow Waters along the Abu Dhabi Coast

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 985 ◽  
Author(s):  
Waleed Hamza ◽  
Letizia Lusito ◽  
Francesco Ligorio ◽  
Giuseppe Tomasicchio ◽  
Felice D’Alessandro
Keyword(s):  
Shallow Water ◽  
Numerical Models ◽  
Grid Point ◽  
Arabian Gulf ◽  
Acoustic Doppler Current Profiler ◽  
Wave Climate ◽  
Abu Dhabi ◽  
Water Conditions ◽  
Key Factor ◽  
Offshore Wave

High-resolution, reliable global atmospheric and oceanic numerical models can represent a key factor in designing a coastal intervention. At the present, two main centers have the capabilities to produce them: the National Oceanic and Atmospheric Administration (NOAA) in the U.S.A. and the European Centre for Medium-Range Weather Forecasts (ECMWF). The NOAA and ECMWF wave models are developed, in particular, for different water regions: deep, intermediate, and shallow water regions using different types of spatial and temporal grids. Recently, in the Arabian Gulf (also named Persian Gulf), the Abu Dhabi Municipality (ADM) installed an ADCP (Acoustic Doppler Current Profiler) to observe the atmospheric and oceanographic conditions (water level, significant wave height, peak wave period, water temperature, and wind speed and direction) at 6 m water depth, in the vicinity of the shoreline of the Saadiyat beach. Courtesy of Abu Dhabi Municipality, this observations dataset is available; the recorded data span the period from June 2015 to January 2018 (included), with a time resolution of 10 min and 30 min for the atmospheric and oceanographic variables, respectively. At the ADCP deployment location (ADMins), the wave climate has been determined using wave propagation of the NOAA offshore wave dataset by means of the Simulating WAves Nearshore (SWAN) numerical model, the NOAA and ECMWF wave datasets at the closest grid point in shallow water conditions, and the SPM ’84 hindcasting method with the NOAA wind dataset used as input. It is shown that the best agreement with the observed wave climate is obtained using the SPM ’84 hindcasting method for the shallow water conditions.

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