scholarly journals Infragravity Wave Energy Partitioning in the Surf Zone in Response to Wind-Sea and Swell Forcing

2019 ◽  
Vol 7 (11) ◽  
pp. 383
Author(s):  
Stephanie Contardo ◽  
Graham Symonds ◽  
Laura Segura ◽  
Ryan Lowe ◽  
Jeff Hansen
Keyword(s):  
Surf Zone ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Sea Breeze ◽  
Peak Frequency ◽  
Short Wave ◽  
Edge Waves ◽  
Leaky Waves ◽  
Wind Speeds ◽  
Wind Sea

An alongshore array of pressure sensors and a cross-shore array of current velocity and pressure sensors were deployed on a barred beach in southwestern Australia to estimate the relative response of edge waves and leaky waves to variable incident wind wave conditions. The strong sea breeze cycle at the study site (wind speeds frequently > 10 m s−1) produced diurnal variations in the peak frequency of the incident waves, with wind sea conditions (periods 2 to 8 s) dominating during the peak of the sea breeze and swell (periods 8 to 20 s) dominating during times of low wind. We observed that edge wave modes and their frequency distribution varied with the frequency of the short-wave forcing (swell or wind-sea) and edge waves were more energetic than leaky waves for the duration of the 10-day experiment. While the total infragravity energy in the surf zone was higher during swell forcing, edge waves were more energetic during wind-sea periods. However, low-frequency (0.005–0.023 Hz) edge waves were found to be dominant in absence of wind-sea conditions, while higher-frequency (0.023–0.050 Hz) edge waves dominated when wind-sea conditions were present.

Crescentic bedforms in the nearshore region

1999 ◽  
Vol 381 ◽  
pp. 271-303 ◽  
Author(s):  
G. VITTORI ◽  
H. E. DE SWART ◽  
P. BLONDEAUX
Keyword(s):  
Surf Zone ◽  
Wind Waves ◽  
Low Frequency ◽  
Feedback Mechanism ◽  
Sediment Flux ◽  
Edge Waves ◽  
Incoming Wave ◽  
Amplification Rate ◽  
Positive Feedback Mechanism ◽  
Local Depth

A wave of small amplitude is considered which approaches a straight beach normally and which is partially reflected at the coastline. By assuming that the local depth is much smaller than the length of the incoming wave, the shallow water equations are used to determine the water motion. The surf zone width is assumed to be small compared to the length of the incoming wave and hence the effect of wave breaking is included only parametrically. The time development of the cohesionless bottom is described by the Exner continuity equation and by an empirical sediment transport rate formula which relates the sediment flux to the steady currents and wave stirring. It is shown that the basic-state solution, which does not depend on the longshore coordinate, may be unstable with respect to longshore bedform perturbations, so that rhythmic topographies form. The instability process is due to a positive feedback mechanism involving the incoming wave, synchronous edge waves and the bedforms. The growth of the bottom perturbations is related to the presence of steady currents caused by the interaction of the incoming wave with synchronous edge waves which in turn are excited by the incoming wave moving over the wavy bed. For natural beaches the model predicts two maxima in the amplification rate: one is related to incoming waves of low frequency, the other to wind waves. Thus two bedforms of different wavelengths can coexist in the nearshore region with longshore spacings of a few hundred and a few tens of metres, respectively. To illustrate the potential validity of the model, its results are compared with field data. The overall agreement is fairly satisfactory.

scholarly journals SHORT WAVE BREAKING EFFECTS ON LOW FREQUENCY WAVES

2011 ◽  
Vol 1 (32) ◽  
pp. 20 ◽  
Author(s):  
Christopher Daly ◽  
Dano Roelvink ◽  
Ap Van Dongeren ◽  
Jaap Van Thiel de Vries ◽  
Robert McCall
Keyword(s):  
Wave Breaking ◽  
Surf Zone ◽  
Low Frequency ◽  
Breaking Waves ◽  
Short Wave ◽  
Frequency Wave ◽  
Wave Heights ◽  
Wave Groupiness ◽  
Set Up ◽  
Low Frequency Waves

The effect of short wave breaking on low frequency waves is investigated using two breaker formulations implemented in a time-dependent numerical model (XBeach): (1) an advective-deterministic approach (ADA) and (2) the probabilistic breaker formulation of Roelvink (1993). Previous research has shown that the ADA breaker model gives different results for the cross-shore pattern of the fraction of breaking waves, which is now shown to affect not only the short wave height but also the short wave groupiness. While RMS short wave heights are comparable to measurements using both breaker models, the ADA breaker model allows higher levels of short wave groupiness into the surf zone. It is shown that this acts as an additional forcing mechanism for low frequency waves in the shoaling and nearshore zone, which, in addition to greater levels of breaking, leads to higher values of wave set-up. These findings are dependent on the complexity of the local bathymetry. For a plane slope, the differences in the low frequency wave heights and set-up predicted by both breaker models are negligible. Where arbitrary breakpoints are present in the field of wave propagation, such as nearshore bars or reefs, the ADA model predicts higher localized set-up, indicative of greater flow over such features. Differences are even more pronounced when the incident wave regime is highly energetic.

scholarly journals Reynolds averaged Navier–Stokes modelling of long waves induced by a transient wave group on a beach

2010 ◽  
Vol 467 (2129) ◽  
pp. 1215-1242 ◽  
Author(s):  
Javier L. Lara ◽  
Andrea Ruju ◽  
Inigo J. Losada
Keyword(s):  
Surf Zone ◽  
Low Frequency ◽  
Short Wave ◽  
Long Waves ◽  
Navier Stokes ◽  
Type Model ◽  
Maker Movement ◽  
Wave Group ◽  
Transient Wave ◽  
Reynolds Averaged Navier Stokes

This paper presents the numerical modelling of the cross shore propagation of infragravity waves induced by a transient focused short wave group over a sloping bottom. A dataset obtained through new laboratory experiments in the wave flume of the University of Cantabria is used to validate the Reynolds averaged Navier–Stokes type model IH-2VOF. A new boundary condition based on the wave maker movement used in the experiments is implemented in the model. Shoaling and breaking of short waves as well as the enhancement of long waves and the energy transfer to low-frequency motion are well addressed by the model, proving the high accuracy in the reproduction of surf zone hydrodynamics. Under the steep slope regime, a long wave trough is radiated offshore from the breakpoint. Numerical simulations conducted for different bottom slopes and short wave steepness suggest that this low-frequency breakpoint generated wave is controlled by both the bed slope parameter and the Iribarren number. Moreover, the numerical model is used to investigate the influence that a large flat bottom induces on the propagation pattern of long waves.

scholarly journals 82 Struggle behavior and vocalizations of male piglets during castration

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 3-4
Author(s):  
Maria E Lou ◽  
Yuzhi Li ◽  
Beth Ventura
Keyword(s):  
Birth Weight ◽  
Acute Pain ◽  
High Frequency ◽  
Video Recording ◽  
Low Frequency ◽  
Peak Frequency ◽  
Analysis Software ◽  
Chi Square ◽  
Behavioral Indicators ◽  
Treatment Groups

Abstract Castration without the use of analgesia is routinely performed on male piglets. The objective of this study was to assess acute pain during castration through behavioral indicators. Piglets (n=88) were randomly allocated to one of two treatments: castration without the use of analgesia (C) and sham-castration (S). Within 24 hours after birth (birth weight = 1.78kg ±0.71), identical procedures were followed for both treatment groups, except sham piglets were not castrated. Struggle behavior (curl ups, leg kicks, and body flailing) and vocalizations were collected via continuous video recording as piglets received treatment from start (first application of scalpel) to end (application of iodine). Vocalization parameters (duration and peak frequency) were analyzed using the Raven Pro: Interactive Sound Analysis Software (Version 1.5). Peak frequency was defined as low (< 1000 Hz) and high (≥ 1000 Hz). Data were analyzed using the Glimmix Procedure of SAS. For struggle behavior, treatment did not affect curl up frequency. However, castrated piglets kicked more frequently than did sham piglets (C=28.8±0.9 vs. S=21.3±0.9 kicks/min; P=0.02). Additionally, 52% of castrated piglets displayed body flailing, whereas only 4.4% of sham piglets displayed the same behavior (Chi-Square = 24.2; P < 0.0001). For vocalizations, no difference was found for duration and peak frequency of low frequency calls. However, castrated piglets responded with more high frequency calls than sham piglets (C=23.6±0.3 vs. S=18.6±0.3 calls/min; P=0.04). High frequency calls tended to be of longer duration for castrated piglets (C=0.45±0.04 vs. S=0.27±0.04 sec/call; P=0.08). Results indicate that castration without the use of analgesia increased the frequency of leg kicks, body failing, and high frequency calls. This suggests that leg kicks, body flailing, and high frequency calls maybe useful behavioral indicators of acute pain in piglets.

scholarly journals Estimation of the Noise Source Level of a Commercial Ship Using On-Board Pressure Sensors

2021 ◽  
Vol 11 (3) ◽  
pp. 1243
Author(s):  
Hongseok Jeong ◽  
Jeung-Hoon Lee ◽  
Yong-Hyun Kim ◽  
Hanshin Seol
Keyword(s):  
Noise Source ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Source Strength ◽  
Recording Time ◽  
Source Level ◽  
The One ◽  
Hydrophone Array ◽  
Good Agreement

The dominant underwater noise source of a ship is known to be propeller cavitation. Recently, attempts have been made to quantify the source strength using on-board pressure sensors near the propeller, as this has advantages over conventional noise measurement. In this study, a beamforming method was used to estimate the source strength of a cavitating propeller. The method was validated against a model-scale measurement in a cavitation tunnel, which showed good agreement between the measured and estimated source levels. The method was also applied to a full-scale measurement, in which the source level was measured using an external hydrophone array. The estimated source level using the hull pressure sensors showed good agreement with the measured one above 400 Hz, which shows potential for noise monitoring using on-board sensors. A parametric study was carried out to check the practicality of the method. From the results, it was shown that a sufficient recording time is required to obtain a consistent level at high frequencies. Changing the frequency resolution had little effect on the result, as long as enough data were provided for the one-third octave band conversion. The number of sensors affected the mid- to low-frequency data.

scholarly journals Meteorological conditions over Antarctic blue-ice areas and their influence on the local surface mass balance

2001 ◽  
Vol 47 (156) ◽  
pp. 37-50 ◽  
Author(s):  
Richard Bintanja ◽  
Carleen H. Reijmer
Keyword(s):  
Mass Balance ◽  
Low Frequency ◽  
Meteorological Conditions ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Wind Speeds ◽  
Dry Conditions ◽  
The Difference ◽  
Sublimation Rates ◽  
Different Characteristics

AbstractThis paper addresses the causes of the prevailing meteorological conditions observed over an Antarctic blue-ice area and their effect on the surface mass balance. Over blue-ice areas, net accumulation is zero and ablation occurs mainly through sublimation. Sublimation rates are much higher than over adjacent snowfields. The meteorological conditions favourable for high sublimation rates (warm, dry and gusty) are due to the specific orographic setting of this blue-ice area, with usually a steep upwind mountainous slope causing strong adiabatic heating. Diabatic warming due to radiation, and entrainment of warm air from aloft into the boundary layer augment the warming. The prevailing warm, dry conditions explain roughly 50% of the difference in sublimation, and the different characteristics of blue ice (mainly its lower albedo) the other 50%. Most of the annual sublimation (∼70%) takes place during the short summer (mainly in daytime), with winter ablation being restricted to occasional warm, dry föhn-like events. The additional moisture is effectively removed by entrainment and horizontal advection, which are maximum over the blue-ice area. Low-frequency turbulent motions induced by the upwind mountains enhance the vertical turbulent transports. Strong gusts and high peak wind speeds over blue-ice areas cause high potential snowdrift transports, which can easily remove the total precipitation, thereby maintaining zero accumulation.

scholarly journals Dynamics and Protein–Solvent Interactions of Hemoglobin in T and R Quaternary Conformation

2002 ◽  
Vol 16 (3-4) ◽  
pp. 227-233 ◽  
Author(s):  
Chiara Caronna ◽  
Antonio Cupane
Keyword(s):  
Quaternary Structure ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Helical Structure ◽  
Blue Shift ◽  
Peak Frequency ◽  
The Other ◽  
Solvent Interactions ◽  
Reported Data ◽  
Increasing Temperature

In this work we report the thermal behaviour of the amide I′ band of carbonmonoxy and deoxy hemoglobin in 65% v/v glycerolD8/D2O solutions and in the temperature interval 10–295 K. Following recent suggestions in the literature, we analyze the amide I′ band in terms of two components, one at about 1630 cm−1and the other at about 1650 cm−1, that are assigned to solvent‒exposed and buried α‒helical regions, respectively.For deoxy hemoglobin (in T quaternary structure) both components are narrower with respect to carbonmonoxy hemoglobin (in R quaternary structure), while the peak frequency blue shift observed, upon increasing temperature, for the component at about 1630 cm−1is smaller. The reported data provide evidence of the dependence of hemoglobin dynamic properties upon the protein quaternary structure and suggest a more compact α‒helical structure of hemoglobin in T conformation, with reduced population of low‒frequency modes involving the solvent and protein.

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 EXCITATION OF LOW FREQUENCY TRAPPED WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 25
Author(s):  
Robert King ◽  
Ronald Smith
Keyword(s):  
Incident Wave ◽  
Standing Waves ◽  
Low Frequency ◽  
Nonlinear Interactions ◽  
Edge Waves ◽  
Constant Depth ◽  
Side Band ◽  
Rectangular Basin ◽  
Trapped Wave ◽  
Narrow Wave

Weak nonlinear interactions in water of non-constant depth between an incident wave, a side-band incident wave and a relatively low frequency trapped wave are shown to lead to the generation of the trapped wave. Three situations are considered in detail: edge waves in a wide rectangular basin, progressive edge waves on a straight beach, and standing waves in a narrow wave tank.

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