scholarly journals Statistical properties of wave kinematics in long-crested irregular waves propagating over non-uniform bathymetry

2021 ◽  
Vol 33 (4) ◽  
pp. 046601
Author(s):  
C. Lawrence ◽  
K. Trulsen ◽  
O. Gramstad
Keyword(s):  
Statistical Properties ◽  
Irregular Waves ◽  
Wave Kinematics

scholarly journals STATISTICAL PROPERTIES OF THE MAXIMUM RUN OF IRREGULAR SEA WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 48 ◽  
Author(s):  
Akira Kimura
Keyword(s):  
Probability Distribution ◽  
Wave Height ◽  
Probability Distributions ◽  
Confidence Regions ◽  
Statistical Properties ◽  
Irregular Waves ◽  
Sea Waves ◽  
Sea State ◽  
Irregular Wave ◽  
Distribution Of The Maximum

The probability distribution of the maximum run of irregular wave height is introduced theoretically. Probability distributions for the 2nd maximum, 3rd maximum and further maximum runs are also introduced. Their statistical properties, including the means and their confidence regions, are applied to the verification of experiments with irregular waves in the realization of a "severe sea state" in the test.

A Lagrangian Model for Irregular Waves and Wave Kinematics

2003 ◽  
Vol 125 (2) ◽  
pp. 94-102 ◽  
Author(s):  
Svein Helge Gjøsund
Keyword(s):  
Iterative Method ◽  
Irregular Waves ◽  
Lagrangian Model ◽  
Surface Zone ◽  
Wave Interactions ◽  
Wave Flume ◽  
Wave Kinematics ◽  
Eulerian Formulation ◽  
The Waves ◽  
Good Agreement

It has proven difficult to describe the kinematics in irregular waves satisfactorily, in particular for the surface zone in broad-banded waves. A Lagrangian approach offers distinct advantages in this respect, eliminating the need for extrapolation of solutions or “stretching” of coordinates. This paper presents a model of irregular waves based on superposition of linear Lagrangian wave components, using an iterative method to obtain the Eulerian solution. This approach yields theoretically consistent results everywhere in the waves, and comparisons with wave flume measurements show good agreement. Also, the linear Lagrangian model includes wave interactions that would be nonlinear in an Eulerian formulation.

THE MOVEMENT OF OIL AT SEA DUE TO IRREGULAR WAVES

2008 ◽  
Vol 2008 (1) ◽  
pp. 943-947
Author(s):  
Ryan D. Bechtel ◽  
Erik Wickley-Olsen ◽  
Michel C. Boufadel* ◽  
James Weaver ◽  
Christopher Barker
Keyword(s):  
Turbulent Diffusion ◽  
Oil Spills ◽  
Vertical Movement ◽  
Irregular Waves ◽  
Subsurface Hydrology ◽  
Wave Kinematics ◽  
Dispersed Oil ◽  
Realistic Situation ◽  
Model Oil ◽  
Neutrally Buoyant

ABSTRACT Our previous work investigated the transport of oil under regular waves at sea. This work considered irregular waves represented by a JONSWAP spectrum, which is a more realistic situation. Particle tracking was used in a Monte Carlo framework to evaluate the combined effects of wave kinematics and turbulent diffusion on the transport of oil droplets at sea. The centroids, variance and spreading coefficients of oil spills with various wave parameters were found in this study. Turbulent diffusion was assumed to be velocity-dependent, and an empirical formulation adopted from subsurface hydrology was adopted. Five hundred neutrally-buoyant oil “particles” were placed at the water surface and tracked for 1 hour. The vertical movement of the plume appeared to be comparable to the significant wave height (about one meter herein), and to decrease with depth. The increase in wind fetch caused an increase in transport and spreading of the plume. The results found in this study can be used by spill responders as a first approximation to the spread of a dispersed oil spill, or can be used as parameters as part of a more complex code used to model oil spills.

Large-Scale Wave Kinematics Measurements of Regular Waves and Large-Amplitude Wave Groups

2010 ◽  
Author(s):  
Lisa Minnick ◽  
Christopher Bassler ◽  
Scott Percival ◽  
Lauren Hanyok
Keyword(s):  
Free Surface ◽  
Large Scale ◽  
Near Field ◽  
Field Measurements ◽  
Primary Objective ◽  
Irregular Waves ◽  
Ship Motions ◽  
Regular Waves ◽  
Wave Groups ◽  
Wave Kinematics

An experiment was performed to measure and characterize wave kinematics in an experimental basin. The experiment is part of an ongoing effort to improve predictions and measurements of ship motions in waves, including more accurate characterization of the near-field wave environment and its influence on ship motions. The primary objective of this experiment was to measure and characterize the wave kinematics of regular waves of varying steepness and scaled irregular seaways, including irregular waves with embedded wave groups. Measurements, including free-surface elevations and velocity field measurements under the free surface, are presented and discussed.

Quantification of Predicted Wave Forces From Distant Elevation Measurements

2019 ◽  
Author(s):  
Spencer T. Hallowell ◽  
Sanjay R. Arwade ◽  
Hannah Johlas ◽  
Pedro Lomonaco ◽  
Andrew Myers
Keyword(s):  
Breaking Waves ◽  
Offshore Structures ◽  
Irregular Waves ◽  
Wave Forces ◽  
Structural Members ◽  
Prediction Equations ◽  
Linear Dispersion ◽  
Force Prediction ◽  
Wave Kinematics ◽  
Wave Measurements

Abstract The vast spatial scale of offshore structures causes wave loading to be correlated amongst nearby structural members. Certain engineering activities including health monitoring, maintenance, and preliminary design of offshore structures requires the prediction of wave forces on said structural members. The high cost and low availability of environmental wave measurements requires the reconstruction of wave kinematics and force profiles to accurately capture the forcing history on offshore structures. A method for predicting wave forces on a cylinder from nearby wave elevation measurements is proposed. The formulation utilizes the Fast Fourier Transform to calculate wave kinematics propagation in the frequency domain and applies the kinematics to the Morison equation for calculation of cylinder forces. The prediction equations are applied to three types of waves: regular periodic waves, random irregular waves, and solitary breaking waves, and the error in both elevation prediction and force prediction when compared to measured values is calculated. The force prediction equations were shown to perform best for small wave heights, with errors as low as 5% in the force predictions for small regular and irregular waves. The error in force prediction increases nonlinearly with the increase in wave height due to the deficiencies of the linear dispersion relationship used in the formulation.

System Identification Techniques for Prediction of Fluid Accelerations Under Irregular Waves Based on Free-Surface Elevation Measurements

2002 ◽  
Author(s):  
Witold Cies´likiewicz ◽  
Ove T. Gudmestad
Keyword(s):  
Time Series ◽  
Particle Acceleration ◽  
Free Surface ◽  
System Identification ◽  
Surface Elevation ◽  
Irregular Waves ◽  
Free Surface Elevation ◽  
Acceleration Time ◽  
Wave Kinematics ◽  
Identification Techniques

A parametric model linking the free-surface elevations with the fluid acceleration field under an irregular wave is developed. In order to estimate the parameters of the model, system identification procedures are applied based on data recorded in a wave tank. The free-surface time series are taken as input data and the output data are components of the particle acceleration vector. The particle acceleration time series were obtained by taking the numerical derivative of the measured orbital velocity time series. A simple algorithm of numerical diffrentiation is proposed. This algorithm gives very accurate values of the particle acceleration and is quite straightforward as the derivative is computed directly in time domain. A linear time-invariant model with the static nonlinearities incorporated at the input side is assumed. This paper demonstrates the results of modelling the horizontal component of the particle acceleration in comparison with the time series calculated from wave kinematics data taken in a wave flume during an earlier experiment using Laser Doppler Velocimetry. The modelled particle acceleration time series compare well with those calculated from the observed velocity time series. This proves the effectiveness of the applied approach. The system identification techniques allow for preparing the model which constructs the wave kinematics (both velocities and accelerations) using the measured time series of only the free-surface elevation. This feature of the proposed approach may be very useful in maritime engineering and oceanography.

scholarly journals Applicability of Nonlinear Wavemaker Theory

2019 ◽  
Vol 7 (1) ◽  
pp. 14 ◽  
Author(s):  
Mads Røge Eldrup ◽  
Thomas Lykke Andersen
Keyword(s):  
Ad Hoc ◽  
Wave Theory ◽  
Wave Generation ◽  
Second Order ◽  
Irregular Waves ◽  
Test Results ◽  
Regular Waves ◽  
Simple Modification ◽  
Wave Kinematics ◽  
Highly Nonlinear

Generation of high-quality waves is essential when making numerical or physically model tests. When using a wavemaker theory outside the validity area, spurious waves are generated. In order to investigate the validity of different wave generation methods, new model test results are presented where linear and nonlinear wave generation theories are tested on regular and irregular waves. A simple modification to the second-order wavemaker theory is presented, which significantly reduces the generation of spurious waves when used outside its range of applicability. For highly nonlinear regular waves, only the ad-hoc unified wave generation based on stream function wave theory was found acceptable. For irregular waves, similar conclusions are drawn, but the modified second-order wavemaker method is more relevant. This is because the ad-hoc unified generation method for irregular waves requires the wave kinematics to be calculated by a numerical model, which might be quite time-consuming. Finally, a table is presented with the range of applicability for each wavemaker method for regular and irregular waves.

Statistical properties of type I intermittency

1982 ◽  
Vol 43 (4) ◽  
pp. 585-589 ◽  
Author(s):  
M. N. Bussac ◽  
C. Meunier
Keyword(s):  
Statistical Properties ◽  
Type I

Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

2020 ◽  
pp. 34-42
Author(s):  
Thibault Chastel ◽  
Kevin Botten ◽  
Nathalie Durand ◽  
Nicole Goutal
Keyword(s):  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Empirical Relationship ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Geometrical Parameters ◽  
Flume Experiments ◽  
Seagrass Meadows ◽  
Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

Sign in / Sign up

Export Citation Format

Share Document