scholarly journals Breaking-wave induced pressure and acceleration on a clifftop boulder

2021 ◽  
Vol 929 ◽  
Author(s):  
James N. Steer ◽  
O. Kimmoun ◽  
F. Dias
Keyword(s):  
High Pressures ◽  
Linear Acceleration ◽  
Wave Crest ◽  
Spectral Energy ◽  
Breaking Wave ◽  
Transport Mechanisms ◽  
Wave Impact ◽  
Storm Waves ◽  
Laboratory Flume ◽  
Wave Induced

The movements of some massive ( ${O}(100)\ \textrm {t}$ ) clifftop boulders, once thought to have been caused by tsunami, have been reattributed to storm waves in several recent papers. However, the precise wave-impact modes and transport mechanisms are unknown. We present preliminary linear acceleration, pressure and displacement data recorded by a $1\,{:}\,30$ scale clifftop boulder impacted by a focused breaking wave in a laboratory flume. The 8 kg boulder was placed atop a 0.25 m high platform and struck with a breaking wave of 0.34 m amplitude. Wave focus position was varied from 0.8 m fore of the platform to 0.27 m aft of the platform to alter the breaking crest shape and wave impact type while maintaining total wave spectral energy. Pressure and acceleration time series measurements from within the boulder show distinct impact types across focus positions. All impacts produced boulder displacement, ranging from 5 mm to 42 mm (0.15 m to 1.3 m at full scale, assuming Froude scaling). The largest boulder pressures were recorded when the wave crest and trough struck the boulder at the same position (flip-through). The largest boulder displacements were measured when high pressures and long impact durations occurred simultaneously and wave focusing was close to flip-through.

Breaking Wave-Induced Dynamic Response of Rubble Mound and Seabed Under a Caisson Breakwater

2009 ◽  
Author(s):  
M. B. C. Ulker ◽  
M. S. Rahman ◽  
M. N. Guddati
Keyword(s):  
Dynamic Response ◽  
Impact Response ◽  
Front Face ◽  
Breaking Wave ◽  
Fe Model ◽  
Wave Impact ◽  
Rubble Mound ◽  
Inertial Terms ◽  
Wave Induced ◽  
The Impact

A finite element (FE) model is developed to study the breaking wave-induced dynamic response of the porous seabed and the rubble mound foundation under a composite caisson-type breakwater. The breaking wave impact pressure distributions on the front face of the breakwater are calculated using a recently proposed method. In this study the focus is on the dynamic response of the foundation materials underneath the breakwater. The impact response of the seabed and the rubble mound is presented in terms of pore pressure and shear stress induced around the breakwater. A complete formulation of the fully dynamic response requires inclusion of the inertial terms associated with both the motion of solid skeleton and that of pore fluid. However, partly dynamic and quasi-static idealizations are also possible. The objective of this study is to investigate the effects of the inertial terms on the breaking wave induced impact response of the seabed as well as the rubble. The effect of seabed saturation on the response from different formulations is also examined.

scholarly journals Computational Fluid Dynamics Investigations of Breaking Focused Wave-Induced Loads on a Monopile and the Effect of Breaker Location

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ankit Aggarwal ◽  
Pietro D. Tomaselli ◽  
Erik Damgaard Christensen ◽  
Hans Bihs
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Air Entrainment ◽  
Wave Crest ◽  
Wave Impact ◽  
Cfd Models ◽  
Impact Forces ◽  
Wave Induced ◽  
The Impact

Abstract The design of new offshore structures requires the calculation of the wave-induced loads. In this regard, the computational fluid dynamics (CFD) methodology has shown to be a reliable tool, in the case of breaking waves especially. In this paper, two CFD models are tested in the reproduction of the experimental spilling waves impacting a circular cylinder for four different wave impact scenarios for focused waves. The numerical and experimental free surface elevations at different locations around the cylinder are also compared to verify the both numerical models. The numerical results from the models are shown together with the experimental measurements. Both CFD models are able to model the impact forces with a reasonable accuracy. When the cylinder is placed at a distance of 0.7 m from the wave breaking point, the value of the measured wave impact forces is highest due to the overturning wave crest and air entrainment. The wave-induced impact forces decrease, when the monopile is placed at distances further away from the breaking location.

The Distribution of Breaking and Non-Breaking Wave Impact Forces

2009 ◽  
Author(s):  
Anne M. Fullerton ◽  
Ann Marie Powers ◽  
Don C. Walker ◽  
Susan Brewton
Keyword(s):  
Breaking Wave ◽  
Wave Impact ◽  
Impact Forces

scholarly journals Assessment of Numerical Methods for Plunging Breaking Wave Predictions

2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Wave Crest ◽  
Breaking Wave ◽  
Rans Turbulence Models ◽  
Run Up ◽  
Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

Sailing Yacht Capsizing

1981 ◽  
Author(s):  
Olin J. Stephens ◽  
Karl L. Kirkman ◽  
Robert S. Peterson
Keyword(s):  
Stability Analysis ◽  
Dynamic Mechanism ◽  
Focused Attention ◽  
Breaking Wave ◽  
Wave Impact ◽  
Single Wave ◽  
Loss Of Life ◽  
Classical Stability ◽  
Sailing Yacht

The 1979 Fastnet focused attention upon yacht capsizes and resulting damage and loss of life. A classical stability analysis does not clearly reveal some of the characteristics of the modern racing yacht which may exacerbate a capsizing tendency. A review of the mechanism of a single-wave-impact capsize reveals inadequacies in static methods of stability analysis and hints at a connection between recent design trends and an increased frequency of capsize. The paper traces recent design trends, relates these to capsizing by a description of the dynamic mechanism of breaking wave impact, and outlines the unusual oceanography of the 1979 Fastnet which led to a heightened incidence of capsize.

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