scholarly journals Stress above Wind-Plus-Paddle Waves: Modeling of a Laboratory Experiment

2007 ◽  
Vol 37 (12) ◽  
pp. 2824-2837 ◽  
Author(s):  
V. K. Makin ◽  
H. Branger ◽  
W. L. Peirson ◽  
J. P. Giovanangeli
Keyword(s):  
Stress Distribution ◽  
Laboratory Experiment ◽  
Wave Field ◽  
Stress Level ◽  
Surface Stress ◽  
Wind Wave ◽  
Wind Waves ◽  
Wave Steepness ◽  
Low Level ◽  
Level Characteristic

Abstract A model based on wind-over-waves coupling (WOWC) theory is used to simulate a laboratory experiment and to explain the observed peculiarities of the surface stress distribution above a combined wave field: wind-generated-plus-monochromatic-paddle waves. Observations show the systematic and significant decrease in the stress as the paddle wave is introduced into the pure wind-wave field. As the paddle-wave steepness is further increased, the stress level returns to the stress level characteristic of the pure wind waves. Further increase in the paddle-wave steepness augments the stress further. The WOWC model explains this peculiarity of the stress distribution by the fact that the paddle waves significantly damp the wind waves in the spectral peak. The stress supported by these dominant waves rapidly falls when the paddle wave is introduced, and this decrease is not compensated by the stress induced by the paddle wave. With further increase in the steepness of the paddle wave, the stress supported by dominant wind waves stays at a low level while the stress supported by the paddle waves continues to grow proportional to the square of the steepness, finally exceeding the stress level characteristic of the pure wind-wave field.

scholarly journals On Evolution of Young Wind Waves in Time and Space

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 562 ◽  
Author(s):  
Shemer
Keyword(s):  
Wave Field ◽  
Field Experiments ◽  
Wind Wave ◽  
Wind Waves ◽  
Wave Generation ◽  
Wind Forcing ◽  
Spatial And Temporal Variation ◽  
Extensive Discussion ◽  
Deterministic Theory ◽  
Theoretical Approaches

The mechanisms governing the evolution of the wind-wave field in time and in space are not yet fully understood. Various theoretical approaches have been offered to model wind-wave generation. To examine their validity, detailed and accurate experiments under controlled conditions have to be carried out. Since it is next to impossible to get the required control of the governing parameters and to accumulate detailed data in field experiments, laboratory studies are needed. Extensive previously unavailable results on the spatial and temporal variation of wind waves accumulated in our laboratory under a variety of wind-forcing conditions and using diverse measuring techniques are reviewed. The spatial characteristics of the wind-wave field were determined using stereo video imaging. The turbulent airflow above wind waves was investigated using an X-hot film. The wave field under steady wind forcing as well as evolving from rest under impulsive loading was studied. An extensive discussion of the various aspects of wind waves is presented from a single consistent viewpoint. The advantages of the stochastic approach suggested by Phillips over the deterministic theory of wind-wave generation introduced by Miles are demonstrated. Essential differences between the spatial and the temporal analyses of wind waves’ evolution are discussed, leading to examination of the applicability of possible approaches to wind-wave modeling.

scholarly journals On the Wave State Dependence of the Sea Surface Roughness at Moderate Wind Speeds under Mixed Wave Conditions

2020 ◽  
Vol 50 (11) ◽  
pp. 3295-3307
Author(s):  
Shuiqing Li ◽  
Zhongshui Zou ◽  
Dongliang Zhao ◽  
Yijun Hou
Keyword(s):  
Surface Roughness ◽  
Wind Wave ◽  
Wind Waves ◽  
Sea Surface ◽  
Wave Steepness ◽  
Threshold Behavior ◽  
Wind Speeds ◽  
Dominant Wave ◽  
Sea Surface Roughness ◽  
Mixed Wave

AbstractWind stress depends on the sea surface roughness, which can be significantly changed by surface wind waves. Based on observations from a fixed platform, we examined the dependences of the sea surface roughness length on dominant wave characteristic parameters (wave age, wave steepness) at moderate wind speeds and under mixed-wave conditions. No obvious trend was found in the wave steepness dependence of sea surface roughness, but a wave steepness threshold behavior was readily identified in the wave age dependence of sea surface roughness. The influence of dominant wind waves on the surface roughness was illustrated using a wind–wave coupling model. The wave steepness threshold behavior is assumed to be related to the onset of dominant wave breaking. The important role of the interaction between swell and wind wave was highlighted, as swell can absorb energy from locally generated wind wave, which subsequently reduces the wave steepness and the probability of dominant wave breaking.

Modelling the Impact of Squall on Wind Waves with the Generalized Kinetic Equation

2015 ◽  
Vol 45 (3) ◽  
pp. 807-812 ◽  
Author(s):  
Sergei Annenkov ◽  
Victor Shrira
Keyword(s):  
Kinetic Equation ◽  
Wave Field ◽  
Wind Wave ◽  
Wind Waves ◽  
Qualitative Difference ◽  
Time Interval ◽  
Short Time Interval ◽  
Spectral Evolution ◽  
Generalized Kinetic Equation ◽  
The Impact

AbstractThis is a first study of short-lived transient sea states, arising from fast variations of wind fields. This study considers the response of a wind-wave field to a sharp increase of wind over a short time interval (a squall). Conventional wind-wave models based on the Hasselmann equation assume quasi stationarity of a random wave field and are a priori inapplicable for such transient states. To describe fast spectral changes, the authors use the generalized kinetic equation (GKE) derived without the quasi-stationarity assumption. A novel efficient highly parallelized algorithm for the numerical simulation of the GKE is presented. Simulations with the GKE and the Hasselmann equation are examined and compared. While under steady wind, the spectral evolution in both cases is shown to be practically identical, but after the squall the qualitative difference emerges: the GKE predicts formation of a transient sea state with a considerably narrower peak.

scholarly journals Loop-Type Wave-Generation Method for Generating Wind Waves under Long-Fetch Conditions

2017 ◽  
Vol 34 (10) ◽  
pp. 2129-2139 ◽  
Author(s):  
Naohisa Takagaki ◽  
Satoru Komori ◽  
Mizuki Ishida ◽  
Koji Iwano ◽  
Ryoichi Kurose ◽  
...  
Keyword(s):  
Wind Wave ◽  
Wind Waves ◽  
Peak Frequency ◽  
Wave Generation ◽  
New Wave ◽  
Wave Tank ◽  
Irregular Wave ◽  
Wind Speeds ◽  
Type Wave ◽  
Wave Generator

AbstractIt is important to develop a wave-generation method for extending the fetch in laboratory experiments, because previous laboratory studies were limited to the fetch shorter than several dozen meters. A new wave-generation method is proposed for generating wind waves under long-fetch conditions in a wind-wave tank, using a programmable irregular-wave generator. This new method is named a loop-type wave-generation method (LTWGM), because the waves with wave characteristics close to the wind waves measured at the end of the tank are reproduced at the entrance of the tank by the programmable irregular-wave generator and the mechanical wave generation is repeated at the entrance in order to increase the fetch. Water-level fluctuation is measured at both normal and extremely high wind speeds using resistance-type wave gauges. The results show that, at both wind speeds, LTWGM can produce wind waves with long fetches exceeding the length of the wind-wave tank. It is observed that the spectrum of wind waves with a long fetch reproduced by a wave generator is consistent with that of pure wind-driven waves without a wave generator. The fetch laws between the significant wave height and the peak frequency are also confirmed for the wind waves under long-fetch conditions. This implies that the ideal wind waves under long-fetch conditions can be reproduced using LTWGM with the programmable irregular-wave generator.

scholarly journals PROPAGATION OF WIND WAVES ON TIDES

1988 ◽  
Vol 1 (21) ◽  
pp. 36 ◽  
Author(s):  
Hendrick L. Tolman
Keyword(s):  
Wave Propagation ◽  
Wind Wave ◽  
Numerical Models ◽  
Wind Waves ◽  
Absolute Frequency ◽  
Shelf Seas ◽  
Shelf Sea

Effects of instationary depths and currents in tides on shelf seas on wind wave propagation are investigated using two numerical models in two academical situations representing shelf sea conditions. It is shown that changes in absolute frequency, which are induced by the instationarity of depth and current, are significant in contrast to what is usually assumed. If these changes are neglected large and unpredictable errors may occur in calculated changes of wavenumber and amplitude.

Raman Spectrum Curve Fitting for Estimating Surface Stress Distribution in Single-Crystal Silicon Microstructure

2009 ◽  
Vol 48 (4) ◽  
pp. 04C021 ◽  
Author(s):  
Mamoru Komatsubara ◽  
Takahiro Namazu ◽  
Yuji Nagai ◽  
Shozo Inoue ◽  
Nobuyuki Naka ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Stress Distribution ◽  
Single Crystal ◽  
Curve Fitting ◽  
Surface Stress ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Spectrum Curve

Improved Spectral Wave Modelling of White-Capping Dissipation in Swell Sea Systems

2004 ◽  
Author(s):  
David P. Hurdle ◽  
Gerbrant Ph. van Vledder
Keyword(s):  
Growth Curve ◽  
Wind Wave ◽  
Wave Component ◽  
Wave Steepness ◽  
Scaling Effects ◽  
Improved Method ◽  
Wave Modelling ◽  
Spectral Components ◽  
Wave Models ◽  
Rate Of Dissipation

An improved method for computing the dissipation by whitecapping in full spectral discrete wind wave models is presented. In this method the rate of dissipation of a certain spectral wave component is determined by the cumulative wave steepness of all spectral components with lower frequencies. This method is known as the cumulative wave steepness method (CSM) and was described by Van Vledder and Hurdle (2002). In this paper some improvements of the CSM are presented which are related to directional and scaling effects. The improved CSM was implemented in the latest release of the SWAN model (version 40.31 of February 2004) and a calibration against a parametric growth curve was performed. Further, the benefits of the CSM in swell-sea systems are illustrated and compared to the method of Komen et al. (1994).

Residual Stress Distribution of Non-Uniform Quenching in Al-Zn-Mg-Cu Aluminum Alloy Thick Plate

2020 ◽  
Vol 1003 ◽  
pp. 11-19
Author(s):  
Ya Nan Li ◽  
Yong An Zhang ◽  
Hong Lei Liu ◽  
Xin Yu Lv ◽  
Xi Wu Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Aluminum Alloy ◽  
Heat Transfer Coefficient ◽  
Stress Distribution ◽  
Transfer Coefficient ◽  
Stress Level ◽  
Transverse Direction ◽  
Residual Stress Distribution ◽  
Surface Quenching

Effect of multi-section linear non-uniform heat transfer coefficient on quenching residual stress distribution in 27mm-thick Al-Zn-Mg-Cu aluminum alloy plate was simulation studied by using the finite element method, and the surface quenching residual stress distribution was measured by the X-ray diffraction method and hole-drilling method. The results show that the surface quenching residual stress represents the same distribution with non-uniform heat transfer coefficient in the transverse direction and the stress level maintains initial stress level of the heat transfer coefficient at each location. The distribution of the quenching residual stress in the center of the plate is approximately uniform and the stress level is approximately equal to average of maximum and minimum initial stress level. The measured surface quenching residual stress shows a wavy distribution in the transverse direction, which is similar to the simulated surface stress distribution without considering the stress level. The measurement results can be explained by the multi-section linear non-uniform quenching model.

Sign in / Sign up

Export Citation Format

Share Document