Burial and Scour of Short Cylinders and Truncated Cones Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Currents

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Muk Chen Ong ◽  
Dag Myrhaug

This paper provides a practical stochastic method by which the burial and scour depths of short cylinders and truncated cones exposed to long-crested (two-dimensional (2D)) and short-crested (three-dimensional (3D)) nonlinear random waves plus currents can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall second-order wave crest height distribution representing both 2D and 3D nonlinear random waves. Moreover, the formulas for the burial and the scour depths for regular waves plus currents presented by previous published work for short cylinders and truncated cones are used.

Author(s):  
Muk Chen Ong ◽  
Dag Myrhaug

This paper provides a practical stochastic method by which the burial and scour depths of short cylinders and truncated cones exposed to long-crested (2D) and short-crested (3D) nonlinear random waves plus currents can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall [1] wave crest height distribution representing both 2D and 3D nonlinear random waves. Moreover, the formulas for the burial and the scour depths for regular waves plus currents presented by Catano-Lopera and Garcia [2, 3] for short cylinders and Catano-Lopera et al. [4] for truncated cones are used.


2021 ◽  
Vol 9 (2) ◽  
pp. 114
Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.


Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong

This paper provides a practical stochastic method by which the maximum scour depth around vertical piles exposed to long-crested (2D) and short-crested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall (2000) wave crest height distribution representing both 2D and 3D nonlinear random waves, and using the regular wave formulas for scour depth by Sumer et al. (1992b). An example of calculation is provided. Tentative approaches to related random wave-induced scour cases are also suggested.


Author(s):  
Felice Arena ◽  
Alfredo Ascanelli

The interest and studies on nonlinear waves are increased recently for their importance in the interaction with floating and fixed bodies. It is also well-known that nonlinearities influence wave crest and wave trough distributions, both deviating from the Rayleigh law. In this paper, a theoretical crest distribution is obtained, taking into account the extension of Boccotti’s quasideterminism theory (1982, “On Ocean Waves With High Crests,” Meccanica, 17, pp. 16–19), up to the second order for the case of three-dimensional waves in finite water depth. To this purpose, the Fedele and Arena (2005, “Weakly Nonlinear Statistics of High Random Waves,” Phys. Fluids, 17(026601), pp. 1–10) distribution is generalized to three-dimensional waves on an arbitrary water depth. The comparison with Forristall’s second order model (2000, “Wave Crest Distributions: Observations and Second-Order Theory,” J. Phys. Oceanogr., 30(8), pp. 1931–1943) shows the theoretical confirmation of his conclusion: The crest distribution in deep water for long-crested and short-crested waves are very close to each other; in shallow water the crest heights in three-dimensional waves are greater than values given by the long-crested model.


Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong

This paper provides a practical stochastic method by which the maximum equilibrium scour depth around vertical piles exposed to long-crested (2D) and short-crested (3D) nonlinear random waves can be derived. The approach is based on assuming the waves to be a stationary narrow-band random process, adopting the Forristall wave crest height distribution (Forristall, 2000, “Wave Crest Distributions: Observations and Second-Order Theory,” J. Phys. Oceanogr., 30, pp. 1931–1943) representing both 2D and 3D nonlinear random waves, and using the regular wave formulas for scour depth by Sumer et al. (1992, “Scour Around Vertical Pile in Waves,” J. Waterway, Port, Coastal, Ocean Eng., 114(5), pp. 599–641). An example calculation is provided. Tentative approaches to related random wave-induced scour cases are also suggested.


Author(s):  
D Myrhaug ◽  
P Hesten ◽  
L E Holmedal

A practical stochastic method for estimating the wave run-up height on a slender vertical circular cylinder for long-crested (two-dimensional (2D)) and short-crested (three-dimensional (3D)) non-linear random waves is provided. This is achieved by using the velocity stagnation head theory in conjunction with a stochastic approach. Here the waves are assumed to be a stationary narrow-band random process. The effects of non-linear waves are included by adopting the Forristall wave crest height distribution representing both 2D and 3D non-linear random waves. A parameter study is provided and, for both 2D and 3D non-linear random waves, the wave run-up height is larger than for linear random waves. In shallow water, when the water is sufficiently shallow, the maximum wave run-up height is larger for 3D waves than for 2D waves. Comparisons are also made with measurements of the maximum wave run-up heights for 2D random waves in a finite water depth by De Vos et al., and it appears that the data are well predicted if the predictions are calibrated with the data. Therefore the present approach represents a model which can be validated against and adjusted to field data.


Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong

A stochastic approach calculating the random wave-induced burial and scour depth of short cylinders and truncated cones on mild slopes is provided. It assumes the waves to be a stationary narrow-band random process and a wave height distribution for mild slopes is adopted, also using formulae for the burial and scour depths for regular waves on horizontal beds for short cylinders and for truncated cones. Examples of results are also provided.


2010 ◽  
Vol 9 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Cuilin Li ◽  
Dingyong Yu ◽  
Yangyang Gao ◽  
Junxian Yang

2020 ◽  
Vol 197 ◽  
pp. 106899 ◽  
Author(s):  
V. Sanil Kumar ◽  
S. Harikrishnan ◽  
Sourav Mandal

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