Shallow Water Breaking Wave Loads on Vertical Cylinders

2013 ◽  
Vol 694-697 ◽  
pp. 659-664
Author(s):  
Li Xu ◽  
Song Gao ◽  
Da Zheng Wang ◽  
N. Barltrop
Keyword(s):  
Water Surface ◽  
Vertical Cylinder ◽  
Breaking Wave ◽  
Total Force ◽  
Outer Diameter ◽  
Wave Loads ◽  
Cylinder Model ◽  
Vertical Cylinders ◽  
Special Case ◽  
Wave Shapes

Many offshore and harbor structures are composed of cylindrical members. In this paper, the special case of shoaling breaking wave loads on a vertical cylinder is investigated in a tank. A segmented cylinder model with outer diameter of 0.204m and total height of 1m was built and tested. Also a 1:20 slope ramp was constructed in the tank to provide the shoaling effect. During the experiments the total force on each segment of the cylinder was measured and the water surface elevations at the cylinder and in deep water were also recorded. Studies on wave shapes and wave loads are presented here.

scholarly journals NUMERICAL MODELING OF TSUNAMI-INDUCED HYDRODYNAMIC FORCES ON ONSHORE STRUCTURES USING SPH

2012 ◽  
Vol 1 (33) ◽  
pp. 81 ◽  
Author(s):  
Philippe St-Germain ◽  
Ioan Nistor ◽  
Ronald Townsend
Keyword(s):  
Water Surface ◽  
Large Scale ◽  
Pressure Field ◽  
Hydrodynamic Forces ◽  
Small Scale ◽  
Breaking Wave ◽  
Total Force ◽  
Riemann Solver ◽  
Wave Impact ◽  
Time Histories

In this paper, the simulation of the violent impact of tsunami-like bores with a square column is performed using a single-phase, weakly compressible three-dimensional Smoothed Particle Hydrodynamics (SPH) model. In order to avoid large fluctuations in the pressure field and to obtain accurate simulations of the hydrodynamic forces, a Riemann solver-based formulation of the SPH method is utilized. Large-scale physical experiments conducted by the authors are reproduced using the numerical model. Time-histories of the water surface elevation as well as time-histories of the pressure distribution and net total force acting on the column are successfully compared. As observed in previous breaking wave impact studies, results show that the magnitude and duration of the impulsive force at initial bore impact depend on the degree of entrapped air in the bore-front. Although ensuring a stable pressure field, the Riemann solver-based SPH scheme is believed to induce excessive numerical diffusion, as sudden and large water surface deformations, such as splashing at initial bore impact, are marginally reproduced. To investigate this particular issue, the small-scale physical experiment of Kleefsman et al. (2005) is also considered and modeled.

Numerical Simulations of Breaking Waves and Steep Waves Past a Vertical Cylinder at Different Keulegan–Carpenter Numbers

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Shengnan Liu ◽  
Muk Chen Ong ◽  
Charlotte Obhrai
Keyword(s):  
Dynamic Pressure ◽  
Vertical Cylinder ◽  
Breaking Waves ◽  
Numerical Results ◽  
Wave Forces ◽  
Breaking Wave ◽  
Wave Loads ◽  
Time Step ◽  
Two Phase ◽  
Steep Waves

A three-dimensional (3D) numerical two-phase flow model based on solving unsteady Reynolds-averaged Navier–Stokes (URANS) equations has been used to simulate breaking waves and steep waves past a vertical cylinder on a 1:10 slope. The volume of fluid (VOF) method is employed to capture the free surface and the k–ω shear–stress transport (k–ω SST) turbulence model is used to simulate the turbulence effects. Mesh and time-step refinement studies have been conducted. The numerical results of wave forces on the structure are compared with the experimental data (Irschik et al., 2004, “Breaking Wave Loads on a Slender Pile in Shallow Water,” Coastal Engineering, Vol. 4, World Scientific, Singapore, pp. 568–581) to validate the numerical model, and the numerical results are in good agreement with the measured data. The wave forces on the structure at different Keulegan–Carpenter (KC) numbers are discussed in terms of the slamming force. The secondary load cycles are observed after the wave front past the structure. The dynamic pressure and velocity distribution, as well as the characteristics of the vortices around the structure at four important time instants, are studied.

Numerical Modeling of Breaking Wave Kinematics and Wave Impact Pressures on a Vertical Slender Cylinder

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Mayilvahanan Alagan Chella ◽  
Hans Bihs ◽  
Dag Myrhaug ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Free Surface ◽  
Breaking Waves ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Breaking Wave ◽  
Total Force ◽  
Wave Loads ◽  
Wave Impact ◽  
Large Wave ◽  
Surface Deformations

Wave loads from breaking waves on offshore wind turbine (OWT) substructures in shallow waters still remain uncertain. The interaction of breaking waves with structures is characterized by complex free surface deformations, instantaneous impact of the water mass against the structure, and consequently large wave forces on the structures. The main objective of the paper is to investigate wave impact pressures and kinematics during the interaction of breaking waves with a vertical cylinder using the open-source computational fluid dynamics (CFD) model REEF3D. The model is based on the Reynolds-averaged Navier–Stokes (RANS) equations coupled with the level set method and k–ω turbulence model. Three wave impact conditions are considered in this study. The numerically simulated free surface deformations around the cylinder during the breaking wave interaction are also presented for different wave impact conditions. For three wave impact conditions, the wave impact pressure and the horizontal and vertical components of the particle velocity are computed in front of the cylinder and analyzed. The pressure and velocity profile at their maximum values are also examined and discussed. In addition, the total force is calculated for three breaking conditions and they are correlated with the pressure and kinematics during the interaction.

scholarly journals Effects of an array of widely separated vertical cylinders on time-averaged properties of progressive monochromatic waves

RBRH ◽  
2020 ◽  
Vol 25 ◽  
Author(s):  
Laura Aguilera ◽  
Paulo Cesar Colonna Rosman ◽  
Claudio Freitas Neves
Keyword(s):  
Wind Farm ◽  
Vertical Cylinder ◽  
Wind Farms ◽  
Wave Climate ◽  
Offshore Wind ◽  
Wave Loads ◽  
Rectangular Array ◽  
Offshore Wind Farms ◽  
Ensemble Effect ◽  
Vertical Cylinders

ABSTRACT The design of monopile foundations for offshore wind farms, the estimate of wave loads, and the effect of the structures on the environment usually consider one single vertical cylinder. This choice is based on the size of the ratio cylinder diameter to wavelength, and on the large distances between turbines. However, for large arrays of monopiles, the ensemble effect must be investigated. This study addresses monochromatic wave propagation through a rectangular array of four cylinders 800 m and 300 m apart, considered here as the fundamental geometry for an arbitrary array of monopiles turbines. Results for bottom velocities, mean water level, mass transport, and radiation stress tensor in the presence of the array are compared with those for a single cylinder. The numerical model WAMIT® is used to compute the potential velocity solution. Relevant spatial variations were found, especially for radiation stresses, for different periods and directions of propagation. Diffraction effects on the wave field by the array are significantly stronger than the superposition of individual effects of isolated cylinders under the same conditions. Impacts of the entire wind farm on bottom morphodynamics near the foundations, on the design loads, and on the wave climate past the wind farm are discussed.

Nonlinear wave loads on a slender vertical cylinder

1995 ◽  
Vol 289 ◽  
pp. 179-198 ◽  
Author(s):  
O. M. Faltinsen ◽  
J. N. Newman ◽  
T. Vinje
Keyword(s):  
Free Surface ◽  
Water Waves ◽  
Vertical Cylinder ◽  
Nonlinear Effects ◽  
Total Force ◽  
Surface Boundary ◽  
Wave Loads ◽  
Wave Load ◽  
Outer Domain ◽  
Wave Slope

The diffraction of water waves by a vertical circular cylinder is considered in the regime where the wave amplitude A and cylinder radius a are of the same order, and both are small compared to the wavelength. The wave slope is small, and a conventional linear analysis applies in the outer domain far from the cylinder. Significant nonlinear effects exist in the complementary inner domain close to the cylinder, associated with the free-surface boundary condition. Using inner coordinates scaled with respect to a, it is shown that the leading-order nonlinear contribution to the velocity potential includes terms proportional to both A2a and A3. The wave load which acts on the cylinder near the free surface includes second- and third-harmonic components which are proportional respectively to A2a2 and A3a. In a conventional perturbation analysis, where A [Lt ] a, these components would be ordered in magnitude corresponding to the different powers of A, but here they are of the same order. The second- and third-order components of the total force are of comparable magnitude for practical values of the wave slope.

Computation of Wave Impact Pressures and Kinematics During Plunging Breaking Wave Interaction With a Vertical Cylinder Using CFD Modelling

2017 ◽  
Author(s):  
Mayilvahanan Alagan Chella ◽  
Hans Bihs ◽  
Dag Myrhaug ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Free Surface ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Breaking Waves ◽  
Offshore Wind Turbine ◽  
Breaking Wave ◽  
Total Force ◽  
Wave Impact ◽  
Large Wave ◽  
Surface Deformations

Wave loads from breaking waves on offshore wind turbine (OWT) substructures in shallow waters still remain uncertain. The interaction of breaking waves with structures is characterized by complex free surface deformations, instantaneous impact of the water mass against the structure and consequently large wave forces on the structures. The main objective of the paper is to investigate wave impact pressures and kinematics during the interaction of breaking waves with a vertical cylinder using the open-source CFD model REEF3D. The model is based on the Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the level set method (LSM) and k-ω turbulence model. Three wave impact conditions are considered in the present study. The numerically simulated free surface deformations around the cylinder during the breaking wave interaction are also presented for different wave impact conditions. For three wave impact conditions, the wave impact pressure and the horizontal and vertical components of the particle velocity are computed in front of the cylinder and analyzed. The pressure and velocity profile at their maximum values are also examined and discussed. In addition, the total force is calculated for three breaking conditions and they are correlated with the pressure and kinematics during the interaction.

Experimental study of breaking wave loads on elevated pile cap with rectangular cross-section

2021 ◽  
Vol 227 ◽  
pp. 108878
Author(s):  
Jie Hong ◽  
Kai Wei ◽  
Zhonghui Shen ◽  
Bo Xu ◽  
Shunquan Qin
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Breaking Wave ◽  
Wave Loads ◽  
Pile Cap

Wave Diffraction on Arrays of Vertical Truncated Cylindrical Bodies

2018 ◽  
Author(s):  
Spyros A. Mavrakos ◽  
Ioannis K. Chatjigeorgiou ◽  
Dimitrios N. Konispoliatis
Keyword(s):  
Wave Energy ◽  
Power Transmission ◽  
Wave Loads ◽  
Free Surface Elevation ◽  
Resonant Modes ◽  
Diffracted Waves ◽  
The Individual ◽  
Offshore Wave ◽  
Vertical Cylinders ◽  
Exciting Wave

Offshore Wave Energy Converter (WEC) farms are widely deployed as regards the individual isolated devices aiming at maximum wave energy absorption and facilitating installation and power transmission. This paper summarizes the theory behind the hydrodynamic interactions of diffracted waves by a large array of vertical cylinders. The latter exhibits some remarkable hydrodynamic interference effects — near resonant modes — in waves causing large loads in adjacent elements of the array. Numerical results concerning the exciting wave loads for a variety of different array configurations of truncated and bottomless cylinders are presented and the free surface elevation around the elements of the array is evaluated pointing out the near trapped modes.

Sign in / Sign up

Export Citation Format

Share Document