Wave tank to simulate the movement of oil under breaking waves

International Nuclear Information System (INIS)

Botrus, D.; Wickley-Olsen, E.; Boufadel, M.C.; Weaver, J.W.; Weggle, R.; Lee, K.; Venosa, A.D.

2008-01-01

Methods to mitigate offshore oil spills before they reach the shoreline have been investigated in order to reduce environmental impacts. Artificial dispersants are commonly used on offshore oil spills to decrease the interfacial tension between the oil and water. The wave action helps break the slick into droplets that penetrate into the sea. This paper presented the results of wave tank tests in which the effectiveness of dispersants was evaluated. The focus was on the transport of oil during the breakup of a wave. In this study, the energy dissipation rate per unit mass was evaluated at various depths in the tank for regular and breaking waves. It was shown that breaking waves play an important role in the dispersion of oil at sea. Contrary to previous studies which suggested that the plume moves forward following the breaker, the results of this study showed that the plume splits into two parts, with one part going upstream. Understanding how the plume travels will provide insight as to where to add the dispersant with respect to the location of the breaker. The addition of the dispersant should take place before the location of the breaker. It was concluded that future work should include computational fluid dynamics simulation, as well as the use of a higher resolution camera. 9 refs., 17 figs

Water level effects on breaking wave setup for Pacific Island fringing reefs

Science.gov (United States)

Becker, J. M.; Merrifield, M. A.; Ford, M.

2014-02-01

The effects of water level variations on breaking wave setup over fringing reefs are assessed using field measurements obtained at three study sites in the Republic of the Marshall Islands and the Mariana Islands in the western tropical Pacific Ocean. At each site, reef flat setup varies over the tidal range with weaker setup at high tide and stronger setup at low tide for a given incident wave height. The observed water level dependence is interpreted in the context of radiation stress gradients specified by an idealized point break model generalized for nonnormally incident waves. The tidally varying setup is due in part to depth-limited wave heights on the reef flat, as anticipated from previous reef studies, but also to tidally dependent breaking on the reef face. The tidal dependence of the breaking is interpreted in the context of the point break model in terms of a tidally varying wave height to water depth ratio at breaking. Implications for predictions of wave-driven setup at reef-fringed island shorelines are discussed.

Propagation and Breaking at High Altitudes of Gravity Waves Excited by Tropospheric Forcing

Science.gov (United States)

Prusa, Joseph M.; Smolarkiewicz, Piotr K.; Garcia, Rolando R.

1996-01-01

An anelastic approximation is used with a time-variable coordinate transformation to formulate a two-dimensional numerical model that describes the evolution of gravity waves. The model is solved using a semi-Lagrangian method with monotone (nonoscillatory) interpolation of all advected fields. The time-variable transformation is used to generate disturbances at the lower boundary that approximate the effect of a traveling line of thunderstorms (a squall line) or of flow over a broad topographic obstacle. The vertical propagation and breaking of the gravity wave field (under conditions typical of summer solstice) is illustrated for each of these cases. It is shown that the wave field at high altitudes is dominated by a single horizontal wavelength; which is not always related simply to the horizontal dimension of the source. The morphology of wave breaking depends on the horizontal wavelength; for sufficiently short waves, breaking involves roughly one half of the wavelength. In common with other studies, it is found that the breaking waves undergo "self-acceleration," such that the zonal-mean intrinsic frequency remains approximately constant in spite of large changes in the background wind. It is also shown that many of the features obtained in the calculations can be understood in terms of linear wave theory. In particular, linear theory provides insights into the wavelength of the waves that break at high altitudes, the onset and evolution of breaking. the horizontal extent of the breaking region and its position relative to the forcing, and the minimum and maximum altitudes where breaking occurs. Wave breaking ceases at the altitude where the background dissipation rate (which in our model is a proxy for molecular diffusion) becomes greater than the rate of dissipation due to wave breaking, This altitude, in effect, the model turbopause, is shown to depend on a relatively small number of parameters that characterize the waves and the background state.

The evolution of an internal bore at the Malin shelf break

Directory of Open Access Journals (Sweden)

J. Small

1999-04-01

Full Text Available Observations of internal waves were made at the Malin shelf edge during SESAME (Shelf Edge Studies Acoustic Measurement Experiment, a part of the NERC LOIS-SES experiment, in August-September 1996. These measurements provide a high resolution dataset demonstrating internal wave generation and propagation. This note presents observations of the evolution of an internal bore. The process is shown clearly in a sequence of thermistor chain tows across the shelf break covering a complete tidal cycle, as the double-sided bore transforms into a group of undulations and eventually into more distinct solitary waveforms. Current structures associated with the bore and waves were also observed by ship-mounted ADCP. Analysis of the waveforms in terms of the linear modes and empirical orthogonal functions (EOFs indicate the dominance of the first mode, which is typical of a shallow water seasonal thermocline environment. Determination of the phase speed of the waves from the consecutive ship surveys enabled the Doppler shift in the towed data to be removed, allowing analysis of the real length scales of the waves. The bore evolution has been modelled using a first order non-linear KdV model for the first mode, initialised with the waveform in the first survey. Comparison of the model and the observations show close agreement in the amplitudes, length scales, phase speeds and separations of the leading internal waves as they evolve. Finally, analysis of the observed internal wave shapes indicates that, within the uncertainties of measurement, the wave-lengths lie between those predicted by first and second order soliton theory.Key words. Oceanography: general (continental shelf processes; ocean prediction. Oceanography: physical (internal and inertial waves

The evolution of an internal bore at the Malin shelf break

Directory of Open Access Journals (Sweden)

J. Small

Full Text Available Observations of internal waves were made at the Malin shelf edge during SESAME (Shelf Edge Studies Acoustic Measurement Experiment, a part of the NERC LOIS-SES experiment, in August-September 1996. These measurements provide a high resolution dataset demonstrating internal wave generation and propagation. This note presents observations of the evolution of an internal bore. The process is shown clearly in a sequence of thermistor chain tows across the shelf break covering a complete tidal cycle, as the double-sided bore transforms into a group of undulations and eventually into more distinct solitary waveforms. Current structures associated with the bore and waves were also observed by ship-mounted ADCP. Analysis of the waveforms in terms of the linear modes and empirical orthogonal functions (EOFs indicate the dominance of the first mode, which is typical of a shallow water seasonal thermocline environment. Determination of the phase speed of the waves from the consecutive ship surveys enabled the Doppler shift in the towed data to be removed, allowing analysis of the real length scales of the waves. The bore evolution has been modelled using a first order non-linear KdV model for the first mode, initialised with the waveform in the first survey. Comparison of the model and the observations show close agreement in the amplitudes, length scales, phase speeds and separations of the leading internal waves as they evolve. Finally, analysis of the observed internal wave shapes indicates that, within the uncertainties of measurement, the wave-lengths lie between those predicted by first and second order soliton theory.

Key words. Oceanography: general (continental shelf processes; ocean prediction. Oceanography: physical (internal and inertial waves

Assessing the performance of wave breaking parameterizations in shallow waters in spectral wave models

Science.gov (United States)

Lin, Shangfei; Sheng, Jinyu

2017-12-01

Depth-induced wave breaking is the primary dissipation mechanism for ocean surface waves in shallow waters. Different parametrizations were developed for parameterizing depth-induced wave breaking process in ocean surface wave models. The performance of six commonly-used parameterizations in simulating significant wave heights (SWHs) is assessed in this study. The main differences between these six parameterizations are representations of the breaker index and the fraction of breaking waves. Laboratory and field observations consisting of 882 cases from 14 sources of published observational data are used in the assessment. We demonstrate that the six parameterizations have reasonable performance in parameterizing depth-induced wave breaking in shallow waters, but with their own limitations and drawbacks. The widely-used parameterization suggested by Battjes and Janssen (1978, BJ78) has a drawback of underpredicting the SWHs in the locally-generated wave conditions and overpredicting in the remotely-generated wave conditions over flat bottoms. The drawback of BJ78 was addressed by a parameterization suggested by Salmon et al. (2015, SA15). But SA15 had relatively larger errors in SWHs over sloping bottoms than BJ78. We follow SA15 and propose a new parameterization with a dependence of the breaker index on the normalized water depth in deep waters similar to SA15. In shallow waters, the breaker index of the new parameterization has a nonlinear dependence on the local bottom slope rather than the linear dependence used in SA15. Overall, this new parameterization has the best performance with an average scatter index of ∼8.2% in comparison with the three best performing existing parameterizations with the average scatter index between 9.2% and 13.6%.

Turbulence dissipation under breaking waves and bores in a natural surf zone

NARCIS (Netherlands)

Grasso, F.R.; Castelle, B.; Ruessink, B.G.

2012-01-01

Wave breaking is the primary driver of beach erosion, injecting breaking-induced turbulence at the sea surface and diffusing bed boundary layer turbulence at the sea bed. The limited understanding of the vertical turbulence structure under natural breaking waves, and hence sand entrainment, is one

Vlasov simulation of the relativistic effect on the breaking of large amplitude plasma waves

International Nuclear Information System (INIS)

Xu Hui; Sheng Zhengming; Zhang Jie

2007-01-01

The influence of relativistic and thermal effects on plasma wave breaking has been studied by solving the coupled Vlasov-Poisson equations. When the relativistic effect is not considered, the wave breaking will not occur, provided the initial perturbation is less than certain value as predicted previously, and the largest amplitude of the plasma wave will decrease with the increase of the initial temperature. When the relativistic effect is considered, wave breaking always occurs during the time evolution, irrespective of the initial perturbation amplitude. Yet the smaller the initial perturbation amplitude is, the longer is the time for wave breaking to occur. With large initial perturbations, wave breaking can always occur with the without the relativistic effect. However, the results are significantly different in the two cases. The thermal effects of electrons decrease the threshold value to initial amplitude for wave breaking and large phase velocity makes the nonlinear phenomenon occur more easily. (authors)

SAR Imaging of Wave Tails: Recognition of Second Mode Internal Wave Patterns and Some Mechanisms of their Formation

Science.gov (United States)

da Silva, Jose C. B.; Magalhaes, J. M.; Buijsman, M. C.; Garcia, C. A. E.

2016-08-01

Mode-2 internal waves are usually not as energetic as larger mode-1 Internal Solitary Waves (ISWs), but they have attracted a great deal of attention in recent years because they have been identified as playing a significant role in mixing shelf waters [1]. This mixing is particularly effective for mode-2 ISWs because the location of these waves in the middle of the pycnocline plays an important role in eroding the barrier between the base of the surface mixed layer and the stratified deep layer below. An urgent problem in physical oceanography is therefore to account for the magnitude and distribution of ISW-driven mixing, including mode-2 ISWs. Several generation mechanisms of mode-2 ISWs have been identified. These include: (1) mode-1 ISWs propagating onshore (shoaling) and entering the breaking instability stage, or propagating over a steep sill; (2) a mode-1 ISW propagating offshore (antishoaling) over steep slopes of the shelf break, and undergoing modal transformation; (3) intrusion of the whole head of a gravity current into a three-layer fluid; (4) impingement of an internal tidal beam on the pycnocline, itself emanating from critical bathymetry; (5) nonlinear disintegration of internal tide modes; (6) lee wave mechanism. In this paper we provide methods to identify internal wave features denominated "Wave Tails" in SAR images of the ocean surface, which are many times associated with second mode internal waves. The SAR case studies that are presented portray evidence of the aforementioned generation mechanisms, and we further discuss possible methods to discriminate between the various types of mode-2 ISWs in SAR images, that emerge from these physical mechanisms. Some of the SAR images correspond to numerical simulations with the MITgcm in fully nonlinear and nonhydrostatic mode and in a 2D configuration with realistic stratification, bathymetry and other environmental conditions.Results of a global survey with some of these observations are presented

Breaking the Waves

DEFF Research Database (Denmark)

Christensen, Poul Rind; Kirketerp, Anne

2006-01-01

The paper shortly reveals the history of a small school - the KaosPilots - dedicated to educate young people to carriers as entrepreneurs. In this contribution we want to explore how the KaosPilots managed to break the waves of institutionalised concepts and practices of teaching entrepreneurship....... Following the so-called 'Dogma' concept developed by Danish filmmakers, this contribution aim to explore the key elements making up the recipes guiding the entrepreneurship training program exercised by the school. Key factors forming a community of learning practice are outlined as well as the critical...... pedagogical elements on which the education in entrepreneurship rests....

Sediment transport under breaking waves

DEFF Research Database (Denmark)

Christensen, Erik Damgaard; Hjelmager Jensen, Jacob; Mayer, Stefan

2000-01-01

The sediment transport in the surf zone is modelled by combining a Navier-Stokes solver, a free surface model, a turbulence model, and a sediment transport model. The flow solver is based on the finite volume technique for non-orthogonal grids. The model is capable of simulating the turbulence...... generated at the surface where the wave breaks as well as the turbulence generated near the bed due to the wave-motion and the undertow. In general, the levels of turbulent kinetic energy are found to be higher than experiments show. This results in an over prediction of the sediment transport. Nevertheless...

Probability function of breaking-limited surface elevation. [wind generated waves of ocean

Science.gov (United States)

Tung, C. C.; Huang, N. E.; Yuan, Y.; Long, S. R.

1989-01-01

The effect of wave breaking on the probability function of surface elevation is examined. The surface elevation limited by wave breaking zeta sub b(t) is first related to the original wave elevation zeta(t) and its second derivative. An approximate, second-order, nonlinear, non-Gaussian model for zeta(t) of arbitrary but moderate bandwidth is presented, and an expression for the probability density function zeta sub b(t) is derived. The results show clearly that the effect of wave breaking on the probability density function of surface elevation is to introduce a secondary hump on the positive side of the probability density function, a phenomenon also observed in wind wave tank experiments.

Nonlocal symmetries, solitary waves and cnoidal periodic waves of the (2+1)-dimensional breaking soliton equation

Science.gov (United States)

Zou, Li; Tian, Shou-Fu; Feng, Lian-Li

2017-12-01

In this paper, we consider the (2+1)-dimensional breaking soliton equation, which describes the interaction of a Riemann wave propagating along the y-axis with a long wave along the x-axis. By virtue of the truncated Painlevé expansion method, we obtain the nonlocal symmetry, Bäcklund transformation and Schwarzian form of the equation. Furthermore, by using the consistent Riccati expansion (CRE), we prove that the breaking soliton equation is solvable. Based on the consistent tan-function expansion, we explicitly derive the interaction solutions between solitary waves and cnoidal periodic waves.

Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave-ice model

Science.gov (United States)

Herman, Agnieszka

2017-11-01

In this paper, a coupled sea ice-wave model is developed and used to analyze wave-induced stress and breaking in sea ice for a range of wave and ice conditions. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid grains floating on the water surface that can be connected to their neighbors by elastic joints. The joints may break if instantaneous stresses acting on them exceed their strength. The wave module is based on an open-source version of the Non-Hydrostatic WAVE model (NHWAVE). The two modules are coupled with proper boundary conditions for pressure and velocity, exchanged at every wave model time step. In the present version, the model operates in two dimensions (one vertical and one horizontal) and is suitable for simulating compact ice in which heave and pitch motion dominates over surge. In a series of simulations with varying sea ice properties and incoming wavelength it is shown that wave-induced stress reaches maximum values at a certain distance from the ice edge. The value of maximum stress depends on both ice properties and characteristics of incoming waves, but, crucially for ice breaking, the location at which the maximum occurs does not change with the incoming wavelength. Consequently, both regular and random (Jonswap spectrum) waves break the ice into floes with almost identical sizes. The width of the zone of broken ice depends on ice strength and wave attenuation rates in the ice.

Design of wave breaking experiments and A-Posteriori Simulations

NARCIS (Netherlands)

Kurnia, R.; Kurnia, Ruddy; van Groesen, Embrecht W.C.

2014-01-01

This report presents results of 30 wave breaking experiments conducted in the long wave tank of TU Delft, Department of Maritime and Transport Technology (6,7 and 10-12 March 2014), together with simulations performed before the experiment to determine the required wave maker motion and a-posteriori

Design of wave breaking experiments and A-Posteriori Simulations

NARCIS (Netherlands)

Kurnia, Ruddy; van Groesen, Embrecht W.C.

This report presents results of 30 wave breaking experiments conducted in the long wave tank of TU Delft, Department of Maritime and Transport Technology (6,7 and 10-12 March 2014), together with simulations performed before the experiment to determine the required wave maker motion and a-posteriori

Application of a planetary wave breaking parameterization to stratospheric circulation statistics

Science.gov (United States)

Randel, William J.; Garcia, Rolando R.

1994-01-01

The planetary wave parameterization scheme developed recently by Garcia is applied to statospheric circulation statistics derived from 12 years of National Meteorological Center operational stratospheric analyses. From the data a planetary wave breaking criterion (based on the ratio of the eddy to zonal mean meridional potential vorticity (PV) gradients), a wave damping rate, and a meridional diffusion coefficient are calculated. The equatorward flank of the polar night jet during winter is identified as a wave breaking region from the observed PV gradients; the region moves poleward with season, covering all high latitudes in spring. Derived damping rates maximize in the subtropical upper stratosphere (the 'surf zone'), with damping time scales of 3-4 days. Maximum diffusion coefficients follow the spatial patterns of the wave breaking criterion, with magnitudes comparable to prior published estimates. Overall, the observed results agree well with the parameterized calculations of Garcia.

Wave-Breaking Turbulence in the Ocean Surface Layer

Science.gov (United States)

2016-06-01

2004) used direct numerical simulation ( DNS ) to show that a single breaking wave can energize the surface layer for more than 50 wave periods, and...1941: Dissipation of energy in the locally isotropic turbulence. Dokl. Akad. Nauk SSR, 30, 301–305. Kukulka, T., and K. Brunner, 2015: Passive

PIV measurements of velocities and accelerations under breaking waves on a slope

DEFF Research Database (Denmark)

Vested, Malene Hovgaard; Carstensen, Stefan; Christensen, Erik Damgaard

2017-01-01

waves. In this study, we have investigated the wave kinematics under steep and breaking waves on a laboratory beach with a slope of 1/25. The velocity field was measured by use of Particle Image Velocimetry (PIV) at a sample rate of 96Hz. The high sample rate allowed for the accelerations...... to be determined directly from the sampled velocities. It was found that both velocities and accelerations differ from the ones predicted from common wave theories such as streamfunction theory. This was especially evident at the top part of the wave close to the surface. This was not surprising, since...... the breaking event is a highly non-linear process. The results presented here may facilitate computations of the impact force on offshore structures and furthermore be used for validation of CFD models while altogether shedding light on the mechanisms behind breaking waves....

Large-scale laboratory study of breaking wave hydrodynamics over a fixed bar

Science.gov (United States)

van der A, Dominic A.; van der Zanden, Joep; O'Donoghue, Tom; Hurther, David; Cáceres, Iván.; McLelland, Stuart J.; Ribberink, Jan S.

2017-04-01

A large-scale wave flume experiment has been carried out involving a T = 4 s regular wave with H = 0.85 m wave height plunging over a fixed barred beach profile. Velocity profiles were measured at 12 locations along the breaker bar using LDA and ADV. A strong undertow is generated reaching magnitudes of 0.8 m/s on the shoreward side of the breaker bar. A circulation pattern occurs between the breaking area and the inner surf zone. Time-averaged turbulent kinetic energy (TKE) is largest in the breaking area on the shoreward side of the bar where the plunging jet penetrates the water column. At this location, and on the bar crest, TKE generated at the water surface in the breaking process reaches the bottom boundary layer. In the breaking area, TKE does not reduce to zero within a wave cycle which leads to a high level of "residual" turbulence and therefore lower temporal variation in TKE compared to previous studies of breaking waves on plane beach slopes. It is argued that this residual turbulence results from the breaker bar-trough geometry, which enables larger length scales and time scales of breaking-generated vortices and which enhances turbulence production within the water column compared to plane beaches. Transport of TKE is dominated by the undertow-related flux, whereas the wave-related and turbulent fluxes are approximately an order of magnitude smaller. Turbulence production and dissipation are largest in the breaker zone and of similar magnitude, but in the shoaling zone and inner surf zone production is negligible and dissipation dominates.

Internal wave turbulence near a Texel beach.

Directory of Open Access Journals (Sweden)

Hans van Haren

Full Text Available A summer bather entering a calm sea from the beach may sense alternating warm and cold water. This can be felt when moving forward into the sea ('vertically homogeneous' and 'horizontally different', but also when standing still between one's feet and body ('vertically different'. On a calm summer-day, an array of high-precision sensors has measured fast temperature-changes up to 1 °C near a Texel-island (NL beach. The measurements show that sensed variations are in fact internal waves, fronts and turbulence, supported in part by vertical stable stratification in density (temperature. Such motions are common in the deep ocean, but generally not in shallow seas where turbulent mixing is expected strong enough to homogenize. The internal beach-waves have amplitudes ten-times larger than those of the small surface wind waves. Quantifying their turbulent mixing gives diffusivity estimates of 10(-4-10(-3 m(2 s(-1, which are larger than found in open-ocean but smaller than wave breaking above deep sloping topography.

Breaking strain of neutron star crust and gravitational waves.

Science.gov (United States)

Horowitz, C J; Kadau, Kai

2009-05-15

Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking strain of the neutron star crust. With multimillion ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the breaking strain of pure single crystals is very large and that impurities, defects, and grain boundaries only modestly reduce the breaking strain to around 0.1. Because of the collective behavior of the ions during failure found in our simulations, the neutron star crust is likely very strong and can support mountains large enough so that their gravitational wave radiation could limit the spin periods of some stars and might be detectable in large-scale interferometers. Furthermore, our microscopic modeling of neutron star crust material can help analyze mechanisms relevant in magnetar giant flares and microflares.

Velocity flow field and water level measurements in shoaling and breaking water waves

CSIR Research Space (South Africa)

Mukaro, R

2010-01-01

Full Text Available In this paper we report on the laboratory investigations of breaking water waves. Measurements of the water levels and instantaneous fluid velocities were conducted in water waves breaking on a sloping beach within a glass flume. Instantaneous water...

Bubbles generated from wind-steepened breaking waves: 2. Bubble plumes, bubbles, and wave characteristics

NARCIS (Netherlands)

Leifer, I.; Caulliez, G.; Leeuw, G.de

2006-01-01

Measurements of breaking-wave-generated bubble plumes were made in fresh (but not clean) water in a large wind-wave tunnel. To preserve diversity, a classification scheme was developed on the basis of plume dimensions and "optical density," or the plume's ability to obscure the background. Optically

Breaking phase focused wave group loads on offshore wind turbine monopiles

DEFF Research Database (Denmark)

Ghadirian, Amin; Bredmose, Henrik; Dixen, M.

2016-01-01

The current method for calculating extreme wave loads on offshore wind turbine structures is based on engineering models for non-breaking regular waves. The present article has the aim of validating previously developed models at DTU, namely the OceanWave3D potential flow wave model and a coupled...

Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

Energy Technology Data Exchange (ETDEWEB)

Vigeesh, G.; Steiner, O. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany); Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de [New Mexico State University, Department of Astronomy, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States)

2017-02-01

Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in the Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.

A unified spectral parameterization for wave breaking: From the deep ocean to the surf zone

Science.gov (United States)

Filipot, J.-F.; Ardhuin, F.

2012-11-01

A new wave-breaking dissipation parameterization designed for phase-averaged spectral wave models is presented. It combines wave breaking basic physical quantities, namely, the breaking probability and the dissipation rate per unit area. The energy lost by waves is first explicitly calculated in physical space before being distributed over the relevant spectral components. The transition from deep to shallow water is made possible by using a dissipation rate per unit area of breaking waves that varies with the wave height, wavelength and water depth. This parameterization is implemented in the WAVEWATCH III modeling framework, which is applied to a wide range of conditions and scales, from the global ocean to the beach scale. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Model errors are comparable to those of other specialized deep or shallow water parameterizations. This work shows that it is possible to have a seamless parameterization from the deep ocean to the surf zone.

Medicago Scutellata Seed Dormancy Breaking by Ultrasonic Waves

Directory of Open Access Journals (Sweden)

Nazari Meisam

2014-12-01

Full Text Available In this study dormancy breaking of a hard-coated plant seed, Medicago scutellata, was investigated. The ultrasonic waves effect on the seed germination percentage, germination rate, radicle length and stalk length growth was assessed. Six treatments of waves exposure periods including 0, 1, 3, 5, 7, and 9 minutes were tested under laboratorial conditions. Statistical analyses were done at probability level of 0.01. Results revealed that the ultrasonic waves have a significantly positive effect on the seed dormancy breaking, but there was no linear correlation between the increasing times of exposure with any of the growth features. The best treatment for germination percentage and germination rate was the 7-minute one and the 3-minute one was the best for radicle length growth. Treatments of 3, 5 and 7 minutes had the same effect on stalk length growth and were better than all other treatments. The 9-minute treatment had a negative effect, even lessening the growth of all of the assessed features in comparison with the control treatment.

A Coupled VOF-Eulerian Multiphase CFD Model to Simulate Breaking Wave Impacts on Offshore Structures

DEFF Research Database (Denmark)

Tomaselli, Pietro; Christensen, Erik Damgaard

2016-01-01

Breaking wave-induced loads on offshore structures can be extremely severe. The air entrainment mechanism during the breaking process plays a not well-known role in the exerted forces. This paper present a CFD solver, developed in the Open-FOAM environment, capable of simulating the wave breaking...

The gravitational wave spectrum from cosmological B-L breaking

International Nuclear Information System (INIS)

Buchmueller, W.; Domcke, V.; Kamada, K.; Schmitz, K.

2013-05-01

Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying Ω GW h 2 ∝10 -13 -10 -8 , much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO and BBO/DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

The gravitational wave spectrum from cosmological B-L breaking

Energy Technology Data Exchange (ETDEWEB)

Buchmueller, W.; Domcke, V.; Kamada, K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Schmitz, K. [Tokyo Univ., Kashiwa (Japan). Kavli IPMU (WPI)

2013-05-15

Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying {Omega}{sub GW}h{sup 2}{proportional_to}10{sup -13}-10{sup -8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO and BBO/DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

Simultaneous particle image velocimetry and infrared imagery of microscale breaking waves

International Nuclear Information System (INIS)

Siddiqui, M.H. Kamran; Loewen, Mark R.; Richardson, Christine; Asher, William E.; Jessup, Andrew T.

2001-01-01

We report the results from a laboratory investigation in which microscale breaking waves were detected using an infrared (IR) imager and two-dimensional (2-D) velocity fields were simultaneously measured using particle image velocimetry (PIV). In addition, the local heat transfer velocity was measured using the controlled flux technique. To the best of our knowledge these are the first measurements of the instantaneous 2-D velocity fields generated beneath microscale breaking waves. Careful measurements of the water surface profile enabled us to make accurate estimates of the near-surface velocities using PIV. Previous experiments have shown that behind the leading edge of a microscale breaker the cool skin layer is disrupted creating a thermal signature in the IR image [Jessup et al., J. Geophys. Res. 102, 23145 (1997)]. The simultaneously sampled IR images and PIV data enabled us to show that these disruptions or wakes are typically produced by a series of vortices that form behind the leading edge of the breaker. When the vortices are first formed they are very strong and coherent but as time passes, and they move from the crest region to the back face of the wave, they become weaker and less coherent. The near-surface vorticity was correlated with both the fractional area coverage of microscale breaking waves and the local heat transfer velocity. The strong correlations provide convincing evidence that the wakes produced by microscale breaking waves are regions of high near-surface vorticity that are in turn responsible for enhancing air-water heat transfer rates

On wave breaking for Boussinesq-type models

Science.gov (United States)

Kazolea, M.; Ricchiuto, M.

2018-03-01

We consider the issue of wave breaking closure for Boussinesq type models, and attempt at providing some more understanding of the sensitivity of some closure approaches to the numerical set-up, and in particular to mesh size. For relatively classical choices of weakly dispersive propagation models, we compare two closure strategies. The first is the hybrid method consisting in suppressing the dispersive terms in breaking regions, as initially suggested by Tonelli and Petti in 2009. The second is an eddy viscosity approach based on the solution of a a turbulent kinetic energy. The formulation follows early work by O. Nwogu in the 90's, and some more recent developments by Zhang and co-workers (Ocean Mod. 2014), adapting it to be consistent with the wave breaking detection used here. We perform a study of the behaviour of the two closures for different mesh sizes, with attention to the possibility of obtaining grid independent results. Based on a classical shallow water theory, we also suggest some monitors to quantify the different contributions to the dissipation mechanism, differentiating those associated to the scheme from those of the partial differential equation. These quantities are used to analyze the dynamics of dissipation in some classical benchmarks, and its dependence on the mesh size. Our main results show that numerical dissipation contributes very little to the the results obtained when using eddy viscosity method. This closure shows little sensitivity to the grid, and may lend itself to the development and use of non-dissipative/energy conserving numerical methods. The opposite is observed for the hybrid approach, for which numerical dissipation plays a key role, and unfortunately is sensitive to the size of the mesh. In particular, when working, the two approaches investigated provide results which are in the same ball range and which agree with what is usually reported in literature. With the hybrid method, however, the inception of instabilities

Wave Impacts on Caisson Breakwaters Situated in Multidirectionally Breaking Seas

DEFF Research Database (Denmark)

Grønbech, J.; Burcharth, Hans F.; Frigaard, Peter

1999-01-01

Attention has been addressed to the effects of wave obliquity and multidirectionality on the wave loads on vertical caisson breakwaters situated in non breaking seas. Within the joint European (MAST-LIP-TAW) research project, a 3D model investigation was carried out at Delft Hydraulics to assess...

Approximate equations at breaking for nearshore wave transformation coefficients

Digital Repository Service at National Institute of Oceanography (India)

Chandramohan, P.; Nayak, B.U.; SanilKumar, V.

Based on small amplitude wave theory approximate equations are evaluated for determining the coefficients of shoaling, refraction, bottom friction, bottom percolation and viscous dissipation at breaking. The results obtainEd. by these equations...

Experimental and Numerical Studies on Wave Breaking Characteristics over a Fringing Reef under Monochromatic Wave Conditions

Directory of Open Access Journals (Sweden)

Jong-In Lee

2014-01-01

Full Text Available Fringing reefs play an important role in protecting the coastal area by inducing wave breaking and wave energy dissipation. However, modeling of wave transformation and energy dissipation on this topography is still difficult due to the unique structure. In the present study, two-dimensional laboratory experiments were conducted to investigate the cross-shore variations of wave transformation, setup, and breaking phenomena over an idealized fringing reef with the 1/40 reef slope and to verify the Boussinesq model under monochromatic wave conditions. One-layer and two-layer model configurations of the Boussinesq model were used to figure out the model capability. Both models predicted well (r2>0.8 the cross-shore variation of the wave heights, crests, troughs, and setups when the nonlinearity is not too high (A0/h0<0.07 in this study. However, as the wave nonlinearity and steepness increase, the one-layer model showed problems in prediction and stability due to the error on the vertical profile of fluid velocity. The results in this study revealed that one-layer model is not suitable in the highly nonlinear wave condition over a fringing reef bathymetry. This data set can contribute to the numerical model verification.

Chiral symmetry breaking and confinement - solutions of relativistic wave equations

International Nuclear Information System (INIS)

Murugesan, P.

1983-01-01

In this thesis, an attempt is made to explore the question whether confinement automatically leads to chiral symmetry breaking. While it should be accepted that chiral symmetry breaking manifests in nature in the absence of scalar partners of pseudoscalar mesons, it does not necessarily follow that confinement should lead to chiral symmetry breaking. If chiral conserving forces give rise to observed spectrum of hadrons, then the conjuncture that confinement is responsible for chiral symmetry breaking is not valid. The method employed to answer the question whether confinement leads to chiral symmetry breaking or not is to solve relativistic wave equations by introducing chiral conserving as well as chiral breaking confining potentials and compare the results with experimental observations. It is concluded that even though chiral symmetry is broken in nature, confinement of quarks need not be the cause of it

Bubbles generated from wind-steepened breaking waves: 1. Bubble plume bubbles

NARCIS (Netherlands)

Leifer, I.; Leeuw, G. de

2006-01-01

Measurements of bubble plumes from paddle-amplified, wind stress breaking waves were made in a large wind-wave channel during the LUMINY experiment in fresh (but not clean) water. Bubble plumes exhibited considerable variability with respect to dynamics, bubble size distribution, and physical

Breaking wave impacts on offshore wind turbine foundations

DEFF Research Database (Denmark)

Bredmose, Henrik; Jacobsen, Niels Gjøl

2010-01-01

that for the impacts of spilling breakers the peak force gets smaller the more developed the breaking is. This is in qualitative agreement with a finding from shallow water impacts on vertical walls: the strongest wave loads are associated with breakers that hit the structure with slightly overturning front...

Waves in geophysical fluids tsunamis, rogue waves, internal waves and internal tides

CERN Document Server

Schneider, Wilhelm; Trulsen, Karsten

2006-01-01

Waves in Geophysical Fluids describes: the forecasting and risk evaluation of tsunamis by tectonic motion, land slides, explosions, run-up, and maps the tsunami sources in the world's oceans; stochastic Monte-Carlo simulations and focusing mechanisms for rogue waves, nonlinear wave models, breather formulas, and the kinematics of the Draupner wave; the full story about the discovery of the very large oceanic internal waves, how the waves are visible from above through the signatures on the sea surface, and how to compute them; observations of energetic internal tides and hot spots from several field campaigns in all parts of the world's oceans, with interpretation of spectra. An essential work for students, scientists and engineers working with the fundamental and applied aspects of ocean waves.

Hele-Shaw beach creation by breaking waves: a mathematics-inspired experiment

NARCIS (Netherlands)

Thornton, Anthony Richard; van der Horn, Avraham/Bram; van der Horn, Avraham J.; Gagarina, Elena; Zweers, Wout; van der Meer, Roger M.; Bokhove, Onno

2014-01-01

Fundamentals of nonlinear wave-particle interactions are studied experimentally in a Hele-Shaw configuration with wave breaking and a dynamic bed. To design this configuration, we determine, mathematically, the gap width which allows inertial flows to survive the viscous damping due to the side

Dam break flood wave under different reservoir's capacities and ...

Indian Academy of Sciences (India)

Farhad Hooshyaripor

2017-07-14

Jul 14, 2017 ... Dam failure has been the subject of many hydraulic engineering studies due to its ... the role of the side slopes on dam break flood wave, such that lower side slope ... improve the inputs and advance our knowledge about the.

Gas transfer under breaking waves: experiments and an improved vorticity-based model

Directory of Open Access Journals (Sweden)

V. K. Tsoukala

2008-07-01

Full Text Available In the present paper a modified vorticity-based model for gas transfer under breaking waves in the absence of significant wind forcing is presented. A theoretically valid and practically applicable mathematical expression is suggested for the assessment of the oxygen transfer coefficient in the area of wave-breaking. The proposed model is based on the theory of surface renewal that expresses the oxygen transfer coefficient as a function of both the wave vorticity and the Reynolds wave number for breaking waves. Experimental data were collected in wave flumes of various scales: a small-scale experiments were carried out using both a sloping beach and a rubble-mound breakwater in the wave flume of the Laboratory of Harbor Works, NTUA, Greece; b large-scale experiments were carried out with a sloping beach in the wind-wave flume of Delft Hydraulics, the Netherlands, and with a three-layer rubble mound breakwater in the Schneideberg Wave Flume of the Franzius Institute, University of Hannover, Germany. The experimental data acquired from both the small- and large-scale experiments were in good agreement with the proposed model. Although the apparent transfer coefficients from the large-scale experiments were lower than those determined from the small-scale experiments, the actual oxygen transfer coefficients, as calculated using a discretized form of the transport equation, are in the same order of magnitude for both the small- and large-scale experiments. The validity of the proposed model is compared to experimental results from other researchers. Although the results are encouraging, additional research is needed, to incorporate the influence of bubble mediated gas exchange, before these results are used for an environmental friendly design of harbor works, or for projects involving waste disposal at sea.

On the generation and evolution of internal solitary waves in the southern Red Sea

KAUST Repository

Guo, Daquan

2016-11-28

Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0 degrees N and 16.5 degrees N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though, as the observed generation sites are far away (50 km) from the shelf break and tidal currents are considered relatively weak in the Red Sea. Upon closer examination of the tide properties in the Red Sea and the unique geometry of the basin, it is argued that the steep bathymetry and a relatively strong tidal current in the southern Red Sea provide favorable conditions for the generation of ISWs. To test this hypothesis and further explore the evolution of ISWs in the basin, 2-D numerical simulations with the nonhydrostatic MIT general circulation model (MITgcm) were conducted. The results are consistent with the satellite observations in regard to the generation sites, peak amplitudes and the speeds of first-mode ISWs. Moreover, our simulations suggest that the generation process of ISWs in the southern Red Sea is similar to the tide-topography interaction mechanism seen in the South China Sea. Specifically, instead of ISWs arising in the immediate vicinity of the shelf break via a hydraulic lee wave mechanism, a broad, energetic internal tide is first generated, which subsequently travels away from the shelf break and eventually breaks down into ISWs. Sensitivity runs suggest that ISW generation may also be possible under summer stratification conditions, characterized by an intermediate water intrusion from the strait of Bab el Mandeb.

Quantifying Wave Breaking Shape and Type in the Surf-Zone Using LiDAR

Science.gov (United States)

Albright, A.; Brodie, K. L.; Hartzell, P. J.; Glennie, C. L.

2017-12-01

Waves change shape as they shoal and break across the surf-zone, ultimately dissipating and transferring their energy into turbulence by either spilling or plunging. This injection of turbulence and changes in wave shape can affect the direction of sediment transport at the seafloor, and ultimately lead to morphological evolution. Typical methods for collecting wave data in the surf-zone include in-situ pressure gauges, velocimeters, ultrasonic sensors, and video imagery. Drawbacks to these data collection methods are low spatial resolution of point measurements, reliance on linear theory to calculate sea-surface elevations, and intensive computations required to extract wave properties from stereo 2D imagery. As a result, few field measurements of the shapes of plunging and/or spilling breakers exist, and existing knowledge is confined to results of laboratory studies. We therefore examine the use of a multi-beam scanning Light Detection and Ranging (LiDAR) remote sensing instrument with the goal of classifying the breaking type of propagating waves in the surf-zone and quantitatively determining wave morphometric properties. Data were collected with a Velodyne HDL-32E LiDAR scanner (360° vertical field of view) mounted on an arm of the Coastal Research Amphibious Buggy (CRAB) at the U.S. Army Corps of Engineers Field Research Facility in Duck, North Carolina. Processed laser scan data are used to visualize the lifecycle of a wave (shoaling, breaking, broken) and identify wave types (spilling, plunging, non-breaking) as they pass beneath the scanner. For each rotation of the LiDAR scanner, the point cloud data are filtered, smoothed, and detrended in order to identify individual waves and measure their properties, such as speed, height, period, upward/downward slope, asymmetry, and skewness. The 3D nature of point cloud data is advantageous for research, because it enables viewing from any angle. In our analysis, plan views are used to separate individual waves

Dynamic Excitation of Monopiles by Steep and Breaking Waves: Experimental and Numerical Study

DEFF Research Database (Denmark)

Bredmose, Henrik; Slabiak, Peter; Sahlberg-Nielsen, Lasse

2013-01-01

. Emphasis is given to the observed impulsive excitation of the natural modes by steep and breaking waves. Additionally, springing and ringing-type continuous forcing of the first natural mode is seen for the moderately steep waves. The experiments were carried out at three depths and with two wave climates...

The Science of Surfing Waves and Surfing Breaks - A Review

OpenAIRE

Scarfe, B. E.; Elwany, M. H.S.; Mead, S. T.; Black, K. P.

2003-01-01

Surfing breaks have great social and economic value for coastal communities. In order to preserve and enhance these resources, a common language is needed that will bridge the gap between the colloquial slang of surfers and the technical language of scientists and policy makers. This language is the science of surfing waves and surfing breaks, and the more it is developed and used, the easier relations will be between the interested parties. This paper will create the basis for such a languag...

Atmospheric Transport and Mixing linked to Rossby Wave Breaking in GFDL Dynamical Core

Science.gov (United States)

Liu, C.; Barnes, E. A.

2015-12-01

Atmospheric transport and mixing plays an important role in the global energy balance and the distribution of health-related chemical constituents. Previous studies suggest a close linkage between large-scale transport and Rossby wave breaking (RWB). In this work, we use the GFDL spectral dynamical core to investigate this relationship and study the response of RWB-related transport in different climate scenarios. In a standard control run, we quantify the contribution of RWB to the total transport and mixing of an idealized tracer. In addition, we divide the contribution further into the two types of RWB - anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB) -- and contrast their efficiency at transport and mixing. Our results are compared to a previous study in which the transport ability of the two types of RWB is studied for individual baroclinic wave life-cycles. In a series of sensitivity runs, we study the response of RWB-related transport and mixing to various states of the jet streams. The responses of the mean strength, frequency, and the efficiency of RWB-related transport are documented and the implications for the transport and mixing in a warmer climate are discussed.

Supercontinuum generation in silicon waveguides relying on wave-breaking.

Science.gov (United States)

Castelló-Lurbe, David; Silvestre, Enrique

2015-10-05

Four-wave-mixing processes enabled during optical wave-breaking (OWB) are exploited in this paper for supercontinuum generation. Unlike conventional approaches based on OWB, phase-matching is achieved here for these nonlinear interactions, and, consequently, new frequency production becomes more efficient. We take advantage of this kind of pulse propagation to obtain numerically a coherent octave-spanning mid-infrared supercontinuum generation in a silicon waveguide pumping at telecom wavelengths in the normal dispersion regime. This scheme shows a feasible path to overcome limits imposed by two-photon absorption on spectral broadening in silicon waveguides.

Near-Bed Turbulent Kinetic Energy Budget Under a Large-Scale Plunging Breaking Wave Over a Fixed Bar

Science.gov (United States)

van der Zanden, Joep; van der A, Dominic A.; Cáceres, Iván.; Hurther, David; McLelland, Stuart J.; Ribberink, Jan S.; O'Donoghue, Tom

2018-02-01

Hydrodynamics under regular plunging breaking waves over a fixed breaker bar were studied in a large-scale wave flume. A previous paper reported on the outer flow hydrodynamics; the present paper focuses on the turbulence dynamics near the bed (up to 0.10 m from the bed). Velocities were measured with high spatial and temporal resolution using a two component laser Doppler anemometer. The results show that even at close distance from the bed (1 mm), the turbulent kinetic energy (TKE) increases by a factor five between the shoaling, and breaking regions because of invasion of wave breaking turbulence. The sign and phase behavior of the time-dependent Reynolds shear stresses at elevations up to approximately 0.02 m from the bed (roughly twice the elevation of the boundary layer overshoot) are mainly controlled by local bed-shear-generated turbulence, but at higher elevations Reynolds stresses are controlled by wave breaking turbulence. The measurements are subsequently analyzed to investigate the TKE budget at wave-averaged and intrawave time scales. Horizontal and vertical turbulence advection, production, and dissipation are the major terms. A two-dimensional wave-averaged circulation drives advection of wave breaking turbulence through the near-bed layer, resulting in a net downward influx in the bar trough region, followed by seaward advection along the bar's shoreward slope, and an upward outflux above the bar crest. The strongly nonuniform flow across the bar combined with the presence of anisotropic turbulence enhances turbulent production rates near the bed.

Effects of blast wave to main steam piping under high energy line break condition by TNT model

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung Hyun; Lee, Eung Seok; Chang, Yoon Suk [Kyung Hee University, Yongin (Korea, Republic of)

2016-05-15

The aim of this study is to examine effect of the blast wave according to pipe break position through FE (Finite Element) analyses. If HELB (High Energy Line Break) accident occurs in nuclear power plants, not only environmental effect such as release of radioactive material but also secondary structural defects should be considered. Sudden pipe rupture causes ejection of high temperature and pressure fluid, which acts as a blast wave around the break location. The blast wave caused by the HELB has a possibility to induce structural defects around the components such as safe-related injection pipes and other structures.

Refined Source Terms in WAVEWATCH III with Wave Breaking and Sea Spray Forecasts

Science.gov (United States)

2015-09-30

dissipation and breaking, nonlinear wave-wave interaction, bottom friction, wave-mud interaction, wave-current interaction as well as sea spray flux. These...shallow water outside the surf zone. After careful testing within a comprehensive suite of test bed cases, these refined source terms will be...aim to refine the parameterization of air-sea and upper ocean fluxes, including wind input and sea spray as well as dissipation, and hence improve

Modeling quiescent phase transport of air bubbles induced by breaking waves

Science.gov (United States)

Shi, Fengyan; Kirby, James T.; Ma, Gangfeng

Simultaneous modeling of both the acoustic phase and quiescent phase of breaking wave-induced air bubbles involves a large range of length scales from microns to meters and time scales from milliseconds to seconds, and thus is computational unaffordable in a surfzone-scale computational domain. In this study, we use an air bubble entrainment formula in a two-fluid model to predict air bubble evolution in the quiescent phase in a breaking wave event. The breaking wave-induced air bubble entrainment is formulated by connecting the shear production at the air-water interface and the bubble number intensity with a certain bubble size spectra observed in laboratory experiments. A two-fluid model is developed based on the partial differential equations of the gas-liquid mixture phase and the continuum bubble phase, which has multiple size bubble groups representing a polydisperse bubble population. An enhanced 2-DV VOF (Volume of Fluid) model with a k - ɛ turbulence closure is used to model the mixture phase. The bubble phase is governed by the advection-diffusion equations of the gas molar concentration and bubble intensity for groups of bubbles with different sizes. The model is used to simulate air bubble plumes measured in laboratory experiments. Numerical results indicate that, with an appropriate parameter in the air entrainment formula, the model is able to predict the main features of bubbly flows as evidenced by reasonable agreement with measured void fraction. Bubbles larger than an intermediate radius of O(1 mm) make a major contribution to void fraction in the near-crest region. Smaller bubbles tend to penetrate deeper and stay longer in the water column, resulting in significant contribution to the cross-sectional area of the bubble cloud. An underprediction of void fraction is found at the beginning of wave breaking when large air pockets take place. The core region of high void fraction predicted by the model is dislocated due to use of the shear

Breaking a dark degeneracy with gravitational waves

Energy Technology Data Exchange (ETDEWEB)

Lombriser, Lucas; Taylor, Andy, E-mail: llo@roe.ac.uk, E-mail: ant@roe.ac.uk [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)

2016-03-01

We identify a scalar-tensor model embedded in the Horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. The model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the new field that is equal to the speed of light. While degenerate in scalar fluctuations, self-acceleration of the model implies a present cosmological tensor mode propagation at ∼<95 % of the speed of light with a damping of the wave amplitude that is ∼>5 % less efficient than in general relativity. We show that these discrepancies are endemic to self-accelerated Horndeski theories with degenerate large-scale structure and are tested with measurements of gravitational waves emitted by events at cosmological distances. Hence, gravitational-wave cosmology breaks the dark degeneracy in observations of the large-scale structure between two fundamentally different explanations of cosmic acceleration—a cosmological constant and a scalar-tensor modification of gravity. The gravitational wave event GW150914 recently detected with the aLIGO instruments and its potential association with a weak short gamma-ray burst observed with the Fermi GBM experiment may have provided this crucial measurement.

Wave-Breaking Phenomena and Existence of Peakons for a Generalized Compressible Elastic-Rod Equation

Directory of Open Access Journals (Sweden)

Xiaolian Ai

2014-01-01

Full Text Available Consideration in this paper is the Cauchy problem of a generalized hyperelastic-rod wave equation. We first derive a wave-breaking mechanism for strong solutions, which occurs in finite time for certain initial profiles. In addition, we determine the existence of some new peaked solitary wave solutions.

Video measurements of fluid velocities and water levels in breaking waves

CSIR Research Space (South Africa)

Govender, K

2002-01-01

Full Text Available The cost-effective measurement of the velocity flow fields in breaking water waves, using particle and correlation image velocimetry, is described. The fluid velocities are estimated by tracking the motion of neutrally buoyant particles and aeration...

Breaking wave impact forces on truss support structures for offshore wind turbines

Science.gov (United States)

Cieślikiewicz, Witold; Gudmestad, Ove T.; Podrażka, Olga

2014-05-01

Due to depletion of the conventional energy sources, wind energy is becoming more popular these days. Wind energy is being produced mostly from onshore farms, but there is a clear tendency to transfer wind farms to the sea. The foundations of offshore wind turbines may be truss structures and might be located in shallow water, where are subjected to highly varying hydrodynamic loads, particularly from plunging breaking waves. There are models for impact forces prediction on monopiles. Typically the total wave force on slender pile from breaking waves is a superposition of slowly varying quasi-static force, calculated from the Morison equation and additional dynamical, short duration force due to the impact of the breaker front or breaker tongue. There is not much research done on the truss structures of wind turbines and there are still uncertainties on slamming wave forces, due to plunging breaking waves on those structures. Within the WaveSlam (Wave slamming forces on truss structures in shallow water) project the large scale tests were carried out in 2013 at the Large Wave Flume in Forschungszentrum Küste (FZK) in Hannover, Germany. The following institutions participated in this initiative: the University of Stavanger and the Norwegian University of Science and Technology (project management), University of Gdańsk, Poland, Hamburg University of Technology and the University of Rostock, Germany and Reinertsen AS, Norway. This work was supported by the EU 7th Framework Programme through the grant to the budget of the Integrating Activity HYDRALAB IV. The main aim of the experiment was to investigate the wave slamming forces on truss structures, development of new and improvement of existing methods to calculate forces from the plunging breakers. The majority of the measurements were carried out for regular waves with specified frequencies and wave heights as well as for the irregular waves based on JONSWAP spectrum. The truss structure was equipped with both

A standing pressure wave hypothesis of oscillating forces generated during a steam line break

International Nuclear Information System (INIS)

Tinoco, H.

2001-01-01

A rapid glance at the figure depicting the net forces acting on the reactor vessel and internals, as obtained through a CFD simulation of a BWR steam line break, reveals an amazing oscillating regularity of these forces which is in glaring contrast to the chaotic behaviour of the steam pressure field in the steam annulus. Assuming that the decompression process excites and maintains standing pressure waves in the annular cylindrical region constituted by the steam annulus, it is possible to reconstruct the net forces acting on the reactor vessel and internals through the contribution of almost only the first dispersive mode. If a Neumann boundary condition is assumed at the section connecting the steam annulus to the steam dome, the frequency predicted is approximately % 5.9 higher than that of the CFD simulations. However, this connecting section allows wave transmission, and a more appropriate boundary condition should be one of the Robin type. Therefore, this section is modelled as an absorbing wall, and the corresponding normal impedance is calculated using the CFD simulations. Week non-linear effects can also be observed in the calculated forces through the presence of the first subharmonic. By the methodology described above, an estimate of the forces acting on the reactor vessel and internals of unit 3 of Forsmark Nuclear Power Plant has been obtained. (author)

Penrose limit, spontaneous symmetry breaking, and holography in a pp-wave background

International Nuclear Information System (INIS)

Das, Sumit R.; Gomez, Cesar; Rey, Soo-Jong

2002-01-01

We argue that the gauge theory dual to the type IIB string theory in a ten-dimensional pp-wave background resides on a Euclidean subspace spanning four of the eight transverse coordinates. We then show that the evolution of the string along one of the light cone directions in the bulk is identifiable as the RG flow of the gauge theory, a relation facilitating the 'holography' of the pp-wave background. The 'holography' reorganizes the dual gauge theory into theories defined over Hilbert subspaces of fixed R charge. The reorganization breaks the SO(4,2)xSO(6) symmetry to a maximal subgroup SO(4)xSO(4) spontaneously. We argue that the low-energy string modes may be regarded as Goldstone modes resulting from such a symmetry breaking pattern

Wave Loading and Overtopping on Caisson Breakwaters in Multidirectional Breaking Seas

DEFF Research Database (Denmark)

Grønbech, J.; Hald, Tue; Frigaard, Peter

1997-01-01

The present paper concerns the results and findings of a physical study on wave impacts on vertical caisson breakwaters situated in irregular, multidirectional breaking seas. The study has taken place as a part of the framework programme "Dynamics of Structures" financially supported by the Danish...

Quantification of Surf Zone Bathymetry from Video Observations of Wave Breaking

Science.gov (United States)

Aarninkhof, S.; Ruessink, G.

2002-12-01

Cost-efficient methods to quantify surf zone bathymetry with high resolution in time and space would be of great value for coastal research and management. Automated video techniques provide the potential to do so. Time-averaged video observations of the nearshore zone show bright intensities at locations where waves preferentially break. Highly similar patterns are found from model simulations of depth-induced wave breaking, which show increasing rates of wave dissipation in shallow areas like sand bars. Thus, video observations of wave breaking - at least qualitatively - reflect sub-merged beach bathymetry. In search of the quantification of this relationship, we present a new model concept to map sub-merged beach bathymetry from time-averaged video images. This is achieved by matching model-predicted and video-observed rates of wave dissipation. First, time-averaged image intensities are sampled along a cross-shore array and interpreted in terms of a wave dissipation parameter. This involves a correction for the effect of persistent foam, which is visible at time-averaged video images but not predicted by common wave propagation models. The dissipation profiles thus obtained are used to update an initial beach bathymetry through optimisation of the match between measured and modelled rates of wave dissipation. The latter is done by raising the bottom elevation in areas where the measured dissipation rate exceeds the computed dissipation and vice versa. Since the model includes video data with high resolution in time (typically multiple images over a tidal cycle), it allows for virtually continous monitoring of surfzone bathymetry . Model tests against a synthetic data set of artificially generated wave dissipation profiles have shown the model's capability to accurately reconstruct beach bathymetry, over a wide range of morphological configurations. Maximum model deviations were found in the case of highly developed bar-trough systems (bar heights up to 4 m) and

An extraordinary locally generated nonlinear internal wave on the shelf of northern South China Sea from marine seismic observation

Science.gov (United States)

Tang, Q.

2017-12-01

A secondary nonlinear internal wave (NIW) on the continental shelf of northern South China Sea (SCS) is studied from high resolution seismic data. It is an extraordinary complex NIW combination of two mode-2 NIWs and an NIW of elevation within a short distance of 2 km. The most energetic part of the NIW could be regarded as a mode-2 NIW localized in the upper layer between 40 and 120 m with its onset at 92 km. The vertical particle velocity of 41 cm/s may exceed the critical value of wave breaking and thus collapse the strongest stratification followed by a series of processes including internal wave breaking, overturning, Kelvin-Helmholtz (KH) instability, stratification splitting, and re-stratification eventually. Among these processes, the shear induced KH billows are directly imaged using the seismic method for the first time. The stratification splitting and re-stratification show that the unstable stage lasts only for a few hours and several kilometers. No previous work has reported the wave of elevation occurred in the deep water of 370 m. Different from the periodical NIWs originated from Luzon Strait, this secondary NIW is most likely generated locally at the shelf break during ebb tide. This is also the first seismic observation that a locally generated NIW is analyzed in detail on the continental shelf of northern SCS. A more sophisticated numerical model is necessary to simulate the extraordinary NIW and its accompanying features.

Characteristics of the solitary waves and rogue waves with interaction phenomena in a (2 + 1)-dimensional Breaking Soliton equation

Science.gov (United States)

Hossen, Md. Belal; Roshid, Harun-Or; Ali, M. Zulfikar

2018-05-01

Under inquisition in this paper is a (2 + 1)-dimensional Breaking Soliton equation, which can describe various nonlinear scenarios in fluid dynamics. Using the Bell polynomials, some proficient auxiliary functions are offered to apparently construct its bilinear form and corresponding soliton solutions which are different from the previous literatures. Moreover, a direct method is used to construct its rogue wave and solitary wave solutions using particular auxiliary function with the assist of bilinear formalism. Finally, the interactions between solitary waves and rogue waves are offered with a complete derivation. These results enhance the variety of the dynamics of higher dimensional nonlinear wave fields related to mathematical physics and engineering.

Size distribution of oceanic air bubbles entrained in sea-water by wave-breaking

Science.gov (United States)

Resch, F.; Avellan, F.

1982-01-01

The size of oceanic air bubbles produced by whitecaps and wave-breaking is determined. The production of liquid aerosols at the sea surface is predicted. These liquid aerosols are at the origin of most of the particulate materials exchanged between the ocean and the atmosphere. A prototype was designed and built using an optical technique based on the principle of light scattering at an angle of ninety degrees from the incident light beam. The output voltage is a direct function of the bubble diameter. Calibration of the probe was carried out within a range of 300 microns to 1.2 mm. Bubbles produced by wave-breaking in a large air-sea interaction simulating facility. Experimental results are given in the form of size spectrum.

Interaction between breaking/broken waves and infragravity-scale phenomena to control sediment suspension transport in the surf zone

CSIR Research Space (South Africa)

Smith, GG

2002-07-30

Full Text Available suspension was further found to be related to the onset of lower water-levels associated with infragravity wave action, which corresponded with a predominance of breaking/broken waves. These breaking/broken waves (which are induced by the low water... is transported down- wards. Nadaoka et al. (1989) have furthermore identi?ed an eddy structure whereby the surface roller is dominated by a nearly two-dimensional ?ow structure, bounded below by strongly three- dimensional obliquely descending eddies bringing...

Experiments and computation of onshore breaking solitary waves

DEFF Research Database (Denmark)

Jensen, A.; Mayer, Stefan; Pedersen, G.K.

2005-01-01

This is a combined experimental and computational study of solitary waves that break on-shore. Velocities and accelerations are measured by a two-camera PIV technique and compared to theoretical values from an Euler model with a VOF method for the free surface. In particular, the dynamics of a so......-called collapsing breaker is scrutinized and the closure between the breaker and the beach is found to be akin to slamming. To the knowledge of the authors, no velocity measurements for this kind of breaker have been previously reported....

Wave Loading and Overtopping on Vertical Wall Breakwaters in Multidirectional Breaking Seas

DEFF Research Database (Denmark)

Kofoed, Jens Peter; Grønbech, J.; Hald, Tue

1998-01-01

The present paper concerns the results and findings of a physical study on wave impacts on vertical caisson breakwaters situated in irregular, multidirectional breaking seas. The study has taken place as part of the framework programme "Dynamics of Structures" financially supported by the Danish...

In Pursuit of Internal Waves

Science.gov (United States)

Peacock, Thomas

2014-11-01

Orders of magnitude larger than surface waves, and so powerful that their generation impacts the lunar orbit, internal waves, propagating disturbances of a density-stratified fluid, are ubiquitous throughout the ocean and atmosphere. Following the discovery of the phenomenon of ``dead water'' by early Arctic explorers and the classic laboratory visualizations of the curious St. Andrew's Cross internal wave pattern, there has been a resurgence of interest in internal waves, inspired by their pivotal roles in local environmental and global climate processes, and their profound impact on ocean and aerospace engineering. We detail our widespread pursuit of internal waves through theoretical modeling, laboratory experiments and field studies, from the Pacific Ocean one thousand miles north and south of Hawaii, to the South China Sea, and on to the Arctic Ocean. We also describe our recent expedition to surf the most striking internal wave phenomenon of them all: the Morning Glory cloud in remote Northwest Australia. This work was supported by the National Science Foundation through a CAREER Grant OCE-064559 and through Grants OCE-1129757 and OCE-1357434, and by the Office of Naval Research through Grants N00014-09-1-0282, N00014-08-1-0390 and N00014-05-1-0575.

A Locally Generated High-Mode Nonlinear Internal Wave Detected on the Shelf of the Northern South China Sea From Marine Seismic Observations

Science.gov (United States)

Tang, Qunshu; Xu, Min; Zheng, Chan; Xu, Xing; Xu, Jiang

2018-02-01

In this work, a secondary nonlinear internal wave (NIW) on the continental shelf of the northern South China Sea is investigated using high-resolution seismic imaging and joint inversion of water structure properties combined with in situ hydrographic observations. It is an extraordinary wave combination with two mode-2 NIWs and one elevated NIW occurring within a short distance of 2 km. The most energetic part of the NIW could be regarded as a mode-2 NIW in the upper layer between 40 and 120 m depth. The vertical particle velocity of ˜41 cm/s may exceed the critical value of wave breaking and thus collapse the strong stratification followed by a series of processes including internal wave breaking, overturning, Kelvin-Helmholtz instability, stratification splitting, and eventual restratification. Among these processes, the shear-induced Kelvin-Helmholtz instability is directly imaged using the seismic method for the first time. The stratification splitting and restratification show that the unstable stage lasts only for a few hours and spans several kilometers. It is a new observation that the elevated NIW could be generated in a deepwater region (as deep as ˜370 m). Different from the periodical NIWs originating from the Luzon Strait, this secondary NIW is most likely generated locally, at the continental shelf break during ebb tide.

Copepod Behavior Response in an Internal Wave Apparatus

Science.gov (United States)

Webster, D. R.; Jung, S.; Haas, K. A.

2017-11-01

This study is motivated to understand the bio-physical forcing in zooplankton transport in and near internal waves, where high levels of zooplankton densities have been observed in situ. A laboratory-scale internal wave apparatus was designed to create a standing internal wave for various physical arrangements that mimic conditions observed in the field. A theoretical analysis of a standing internal wave inside a two-layer stratification system including non-linear wave effects was conducted to derive the expressions for the independent variables controlling the wave motion. Focusing on a case with a density jump of 1.0 σt, a standing internal wave was generated with a clean interface and minimal mixing across the pycnocline. Spatial and frequency domain measurements of the internal wave were evaluated in the context of the theoretical analysis. Behavioral assays with a mixed population of three marine copepods were conducted in control (stagnant homogeneous fluid), stagnant density jump interface, and internal wave flow configurations. In the internal wave treatment, the copepods showed an acrobatic, orbital-like motion in and around the internal wave region (bounded by the crests and the troughs of the waves). Trajectories of passive, neutrally-buoyant particles in the internal wave flow reveal that they generally oscillate back-and-forth along fixed paths. Thus, we conclude that the looping, orbital trajectories of copepods in the region near the internal wave interface are due to animal behavior rather than passive transport.

Effect of wind waves on air-sea gas exchange: proposal of an overall CO2 transfer velocity formula as a function of breaking-wave parameter

International Nuclear Information System (INIS)

Zhao, D.; Suzuki, Y.; Komori, S.

2003-01-01

A new formula for gas transfer velocity as a function of the breaking-wave parameter is proposed based on correlating gas transfer with whitecap coverage. The new formula for gas transfer across an air-sea interface depends not only on wind speed but also on wind-wave state. At the same wind speed, a higher gas transfer velocity will be obtained for a more developed wind-sea, which is represented by a smaller spectral peak frequency of wind waves. We suggest that the large uncertainties in the traditional relationship of gas transfer velocity with wind speed be ascribed to the neglect of the effect of wind waves. The breaking-wave parameter can be regarded as a Reynolds number that characterizes the intensity of turbulence associated with wind waves in the downward-bursting boundary layer (DBBL). DBBL provides an effective way to exchange gas across the air-sea interface, which might be related to the surface renewal

Influence of ambient air pressure on impact pressure caused by breaking waves

NARCIS (Netherlands)

Moutzouris, C.

1979-01-01

Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing

On the kinematic criterion for the inception of breaking in surface gravity waves: Fully nonlinear numerical simulations and experimental verification

Science.gov (United States)

Khait, A.; Shemer, L.

2018-05-01

The evolution of unidirectional wave trains containing a wave that gradually becomes steep is evaluated experimentally and numerically using the Boundary Element Method (BEM). The boundary conditions for the nonlinear numerical simulations corresponded to the actual movements of the wavemaker paddle as recorded in the physical experiments, allowing direct comparison between the measured in experiments' characteristics of the wave train and the numerical predictions. The high level of qualitative and quantitative agreement between the measurements and simulations validated the kinematic criterion for the inception of breaking and the location of the spilling breaker, on the basis of the BEM computations and associated experiments. The breaking inception is associated with the fluid particle at the crest of the steep wave that has been accelerated to match and surpass the crest velocity. The previously observed significant slow-down of the crest while approaching breaking is verified numerically; both narrow-/broad-banded wave trains are considered. Finally, the relative importance of linear and nonlinear contributions is analyzed.

Model-based internal wave processing

Energy Technology Data Exchange (ETDEWEB)

Candy, J.V.; Chambers, D.H.

1995-06-09

A model-based approach is proposed to solve the oceanic internal wave signal processing problem that is based on state-space representations of the normal-mode vertical velocity and plane wave horizontal velocity propagation models. It is shown that these representations can be utilized to spatially propagate the modal (dept) vertical velocity functions given the basic parameters (wave numbers, Brunt-Vaisala frequency profile etc.) developed from the solution of the associated boundary value problem as well as the horizontal velocity components. Based on this framework, investigations are made of model-based solutions to the signal enhancement problem for internal waves.

The Impact of Internal Wave Seasonality on the Continental Shelf Energy Budget

Science.gov (United States)

Wihsgott, Juliane U.; Sharples, Jonathan; Hopkins, Joanne; Palmer, Matthew R.; Mattias Green, J. A.

2017-04-01

Heating-stirring models are widely used to simulate the timing and strength of stratification in continental shelf environments. Such models are based on bulk potential energy (PE) budgets: the loss of PE due to thermal stratification is balanced by wind and tidal mixing. The model often fails to accurately predict the observed vertical structure, as it only considers forces acting on the surface and bottom boundary of the water column. This highlights the need for additional internal energy sources to close this budget, and produce an accurate seasonal cycle of stratification. We present new results that test the impact of boundary layer and internal wave forcing on stratification and vertical density structure in continental shelves. A new series of continuous measurements of full water depth vertical structure, dynamics and meteorological data spanning 17 months (March'14-July'15) provide unprecedented coverage over a full seasonal cycle at a station 120 km north-east from the continental shelf break. We observe a highly variable but energetic internal wave field from the onset of stratification that suggests a continuous supply of internal PE. The heating-stirring model reproduces bulk characteristics of the seasonal cycle. While it accurately predicts the timing of the onset in spring and peak stratification in late summer there is a persistent 20 J m-3 positive offset between the model and observations throughout this period. By including a source of internal energy in the model we improve the prediction for the strength of stratification and the vertical distribution of heat. Yet a constant source of PE seems to result in a seasonal discrepancy resulting in too little mixing during strong stratification and too much mixing during transient periods. The discrepancy seen in the model is consistent with the seasonality observed in the internal wave field. We will establish the role that changing stratification (N2) exerts on the internal wave field and vice

A Novel Experimental Set-Up for Improving the Sensitivity of SV Waves to Shallow Surface-Breaking Cracks

Energy Technology Data Exchange (ETDEWEB)

Pecorari, Claudio [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Aeronautical and Vehicle Engineering

2006-03-15

Conventional inspection procedures to detect surface-breaking defects in train axels and thick pipes often employ 45-degree incidence shear vertical (SV) waves as probing tool. Recently obtained theoretical and experimental results indicate that this method is considerably less sensitivity to shallow surface-breaking defects, than the one in which the angle of incidence is selected to be close to the critical angle of the longitudinal wave. This project has confirmed this thesis by experimentally investigating the backscattering of SV waves by surface-breaking cracks as a function o t the angle of incidence. To this end, three cracks of depth approximately equal to 0.3 mm, 0.5 mm and 0.7 were introduced on the surface of steel samples with a thickness of 47 mm. These cracks were insonified with transducers operating at 2.25 MHz, 3.5 MHz, and 5 MHz, which correspond to wavelengths in steel of 1.38 mm, 0.88 mm, and 0.62 mm, respectively. The increase in sensitivity has been assessed in the order of 15 dB.

A study of the radar backscattering from the breaking of wind waves on the sea

International Nuclear Information System (INIS)

Ivanov, V.A.; Yurovskij, Yu.Yu.; Malinovskij, V.V.

2011-01-01

The results of a field study of the relationship between radar backscattering parameters and geometrical characteristics of the wind wave breaking are presented. The radar cross-section of a whitecap is found to be proportional to the breaking crest length. It is shown that the accounting for a change of the non-Bragg scattering in the presence of an oil slick on the sea surface allows one to interpret experimental data correctly.

Measurements of Two-Phase Suspended Sediment Transport in Breaking Waves Using Volumetric Three-Component Velocimetry

Science.gov (United States)

Ting, F. C. K.; LeClaire, P.

2016-02-01

Understanding the mechanisms of sediment pickup and distribution in breaking waves is important for modeling sediment transport in the surf zone. Previous studies were mostly concerned with bulk sediment transport under specific wave conditions. The distribution of suspended sediments in breaking waves had not been measured together with coherent flow structures. In this study, two-phase flow measurements were obtained under a train of plunging regular waves on a plane slope using the volumetric three-component velocimetry (V3V) technique. The measurements captured the motions of sediment particles simultaneously with the three-component, three-dimensional (3C3D) velocity fields of turbulent coherent structures (large eddies) induced by breaking waves. Sediment particles (solid glass spheres diameter 0.125 to 0.15 mm, specific gravity 2.5) were separated from fluid tracers (mean diameter 13 µm, specific gravity 1.3) based on a combination of particle spot size and brightness in the two-phase images. The interactions between the large eddies and glass spheres were investigated for plunger vortices generated at incipient breaking and for splash-up vortices generated at the second plunge point. The measured data show that large eddies impinging on the bottom was the primary mechanism which lift sediment particles into suspension and momentarily increased near-bed suspended sediment concentration. Although eddy impingement events were sporadic in space and time, the distributions of suspended sediments in the large eddies were not uniform. High suspended sediment concentration and vertical sediment flux were found in the wall-jet region where the impinging flow was deflected outward and upward. Sediment particles were also trapped and carried around by counter-rotating vortices (Figure 1). Suspended sediment concentration was significantly lower in the impingement region where the fluid velocity was downward, even though turbulent kinetic energy in the down flow was

Internal Waves, South China Sea

Science.gov (United States)

1983-01-01

Subsurface ocean currents, frequently referred to as internal waves, are frequently seen from space under the right lighting conditions when depth penetration can be achieved. These internal waves observed in the South China Sea off the SE coast of the island of Hainan (18.5N, 110.5E) visibly demonstrate turbidity in the ocean's depths at the confluence of conflicting currents.

Large Scale Experiments on the Interaction of a Caisson Breakwater with Breaking Waves

DEFF Research Database (Denmark)

Stagonas, Dimitris; Marzeddu, Andrea; Buccino, Mariano

2014-01-01

waves, which resulted in impulsive conditions at the face of the caisson. Amongst our objectives was to look at the mechanisms occurring when a wave breaks at the structure and to investigate the validity of tactile pressure sensors. As such, for all experiments, pressure, force and surface elevation...... measurements were complimented with high speed and high definition video records. ln addition, a pressure mapping system employing tactile pressure sensors was deployed in cornbination with force panels, both positioned at still water level. Although at a very early stage, data analysis yields promising...

Internal waves and temperature fronts on slopes

Directory of Open Access Journals (Sweden)

S. A. Thorpe

Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

Breaking Bat

Science.gov (United States)

Aguilar, Isaac-Cesar; Kagan, David

2013-01-01

The sight of a broken bat in Major League Baseball can produce anything from a humorous dribbler in the infield to a frightening pointed projectile headed for the stands. Bats usually break at the weakest point, typically in the handle. Breaking happens because the wood gets bent beyond the breaking point due to the wave sent down the bat created…

Vertical Transport of Momentum by the Inertial-Gravity Internal Waves in a Baroclinic Current

Directory of Open Access Journals (Sweden)

A. A. Slepyshev

2017-08-01

Full Text Available When the internal waves break, they are one of the sources of small-scale turbulence. Small-scale turbulence causes the vertical exchange in the ocean. However, internal waves with regard to the Earth rotation in the presence of vertically inhomogeneous two-dimensional current are able to contribute to the vertical transport. Free inertial-gravity internal waves in a baroclinic current in a boundless basin of a constant depth are considered in the Bussinesq approximation. Boundary value problem of linear approximation for the vertical velocity amplitude of internal waves has complex coefficients when current velocity component, which is transversal to the wave propagation direction, depends on the vertical coordinate (taking into account the rotation of the Earth. Eigenfunction and wave frequency are complex, and it is shown that a weak wave damping takes place. Dispersive relation and wave damping decrement are calculated in the linear approximation. At a fixed wave number damping decrement of the second mode is larger (in the absolute value than the one of the first mode. The equation for vertical velocity amplitude for real profiles of the Brunt – Vaisala frequency and current velocity are numerically solved according to implicit Adams scheme of the third order of accuracy. The dispersive curves of the first two modes do not reach inertial frequency in the low-frequency area due to the effect of critical layers in which wave frequency of the Doppler shift is equal to the inertial one. Termination of the second mode dispersive curves takes place at higher frequency than the one of the first mode. In the second order of the wave amplitude the Stokes drift speed is determined. It is shown that the Stokes drift speed, which is transversal to the wave propagation direction, differs from zero if the transversal component of current velocity depends on the vertical coordinate. In this case, the Stokes drift speed in the second mode is lower than

Quasiparticle conductance-voltage characteristics for break junctions involving d-wave superconductors: charge-density-wave effects.

Science.gov (United States)

Ekino, T; Gabovich, A M; Suan Li, Mai; Szymczak, H; Voitenko, A I

2017-12-20

Quasiparticle tunnel conductance-voltage characteristics (CVCs), [Formula: see text], were calculated for break junctions (BJs) made up of layered d-wave superconductors partially gapped by charge-density waves (CDWs). The current is assumed to flow in the ab-plane of electrodes. The influence of CDWs is analyzed by comparing the resulting CVCs with CVCs calculated for BJs made up of pure d-wave superconductors with relevant parameters. The main CDW-effects were found to be the appearance of new CVC peculiarities and the loss of CVC symmetry with respect to the V-sign. Tunnel directionality was shown to be one of the key factors in the formation of [Formula: see text] dependences. In particular, the orientation of electrodes with respect to the current channel becomes very important. As a result, [Formula: see text] can acquire a large variety of forms similar to those for tunnel junctions between superconductors with s-wave, d-wave, and mixed symmetry of their order parameters. The diversity of peculiarities is especially striking at finite temperatures. In the case of BJs made up of pure d-wave superconductors, the resulting CVC can include a two-peak gap-driven structure. The results were compared with the experimental BJ data for a number of high-T c oxides. It was shown that the large variety of the observed current-voltage characteristics can be interpreted in the framework of our approach. Thus, quasiparticle tunnel currents in the ab-plane can be used as an additional mean to detect CDWs competing with superconductivity in cuprates or other layered superconductors.

Reliability Evaluation of Monolithic Vertical Wall Breakwaters Considering Impulsive Wave Breaking Forces and Failure Modes of the Foundation

DEFF Research Database (Denmark)

Burcharth, H. F.; Sørensen, Jørgen S.; Christiani, E.

1994-01-01

Impulsive wave breaking forces on a vertical caisson breakwater has been included by Takahashi et al, (1994) in Goda's wave pressure formula (Goda et al. 1972 and Goda 1974). Based on these formulae a deterministic design method following the Japanese recommendations has been used for the design...

Sensitivity of Middle Atmospheric Temperature and Circulation in the UIUC Mesosphere-Stratosphere-Troposphere GCM to the Treatment of Subgrid-Scale Gravity-Wave Breaking

Science.gov (United States)

Yang, Fanglin; Schlesinger, Michael E.; Andranova, Natasha; Zubov, Vladimir A.; Rozanov, Eugene V.; Callis, Lin B.

2003-01-01

The sensitivity of the middle atmospheric temperature and circulation to the treatment of mean- flow forcing due to breaking gravity waves was investigated using the University of Illinois at Urbana-Champaign 40-layer Mesosphere-Stratosphere-Troposphere General Circulation Model (MST-GCM). Three GCM experiments were performed. The gravity-wave forcing was represented first by Rayleigh friction, and then by the Alexander and Dunkerton (AD) parameterization with weak and strong breaking effects of gravity waves. In all experiments, the Palmer et al. parameterization was included to treat the breaking of topographic gravity waves in the troposphere and lower stratosphere. Overall, the experiment with the strong breaking effect simulates best the middle atmospheric temperature and circulation. With Rayleigh friction and the weak breaking effect, a large warm bias of up to 60 C was found in the summer upper mesosphere and lower thermosphere. This warm bias was linked to the inability of the GCM to simulate the reversal of the zonal winds from easterly to westerly crossing the mesopause in the summer hemisphere. With the strong breaking effect, the GCM was able to simulate this reversal, and essentially eliminated the warm bias. This improvement was the result of a much stronger meridional transport circulation that possesses a strong vertical ascending branch in the summer upper mesosphere, and hence large adiabatic cooling. Budget analysis indicates that 'in the middle atmosphere the forces that act to maintain a steady zonal-mean zonal wind are primarily those associated with the meridional transport circulation and breaking gravity waves. Contributions from the interaction of the model-resolved eddies with the mean flow are small. To obtain a transport circulation in the mesosphere of the UIUC MST-GCM that is strong enough to produce the observed cold summer mesopause, gravity-wave forcing larger than 100 m/s/day in magnitude is required near the summer mesopause. In

Electromagnetic internal gravity waves in the Earth's ionospheric E-layer

International Nuclear Information System (INIS)

Kaladze, T.D.; Tsamalashvili, L.V.; Kaladze, D.T.

2011-01-01

In the Earth's ionospheric E-layer existence of the new waves connecting with the electromagnetic nature of internal gravity waves is shown. They represent the mixture of the ordinary internal gravity waves and the new type of dispersive Alfven waves. -- Highlights: ► Existence of electromagnetic internal gravity waves in the ionospheric E-layer is shown. ► Electromagnetic nature of internal gravity waves is described. ► Appearance of the new dispersive Alfven waves is shown.

Factors contributing to record-breaking heat waves over the Great Plains during the 1930s Dust Bowl

Science.gov (United States)

Cowan, T.; Hegerl, G. C.

2016-12-01

Record-breaking summer heat waves that plagued contiguous United States in the 1930s emerged during the decade-long "Dust Bowl" drought. Using high-quality daily temperature observations, the Dust Bowl heat wave characteristics for the Great Plains are assessed using metrics that describe variations in heat wave activity and intensity. We also quantify record-breaking heat waves over the pre-industrial period for 22 CMIP5 model multi-century realisations. The most extreme Great Plains heat wave summers in the Dust Bowl decade (e.g. 1931, 1934, 1936) were pre-conditioned by anomalously dry springs, as measured by proxy drought indices. In general, summer heat waves over the Great Plains develop 15-20 days earlier after anomalously dry springs, and are also significantly longer and hotter, indicative of the importance of land surface feedbacks in heat wave intensification. The majority of pre-industrial climate model experiments capture regionally clustered summer heat waves across North America, although the North Pacific and Atlantic sea surface temperature patterns associated with the heat waves vary considerably between models. Sea surface temperature patterns may be more important for influencing winter and spring precipitation, thus amplifying summer heat waves during drought periods. The synoptic pattern that commonly appeared during the exceptional Dust Bowl heat waves featured an anomalous broad surface pressure ridge straddling an upper level blocking anticyclone over the western United States. This forced significant subsidence and adiabatic warming over the Great Plains, and triggered anomalous southward warm advection over southern regions, prolonging and amplifying the heat waves over central United States. Importantly, the results show that despite the sparsity of stations in the 1930s, homogeneous observations are crucial in accurately quantifying the Dust Bowl decade heat waves, as opposed to solely relying on atmospheric reanalysis.

A CFD Investigation on the Effect of the Air Entrainment in Breaking Wave Impacts on a Mono-Pile

DEFF Research Database (Denmark)

Tomaselli, Pietro; Christensen, Erik Damgaard

2017-01-01

In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to repro-duce an experimental investigation on the imp......In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to repro-duce an experimental investigation...... on the impact of a spilling wave against a circular cylinder. The exerted in-line force was computed with and without the inclusion of dispersed bubbles. Results showed that the magnitude of the computed force was affected when the entrainment of bubbles was simulated....

Mean flow generated by an internal wave packet impinging on the interface between two layers of fluid with continuous density

Energy Technology Data Exchange (ETDEWEB)

McHugh, John P. [The University of New Hampshire, Department of Mechanical Engineering, Kingsbury Hall, Durham, NH (United States)

2008-04-15

Internal waves propagating in an idealized two-layer atmosphere are studied numerically. The governing equations are the inviscid anelastic equations for a perfect gas atmosphere. The numerical formulation eliminates all variables in the linear terms except vertical velocity, which are then treated implicitly. Nonlinear terms are treated explicitly. The basic state is a two-layer flow with continuous density at the interface. Each layer has a unique constant for the Brunt-Vaeisaelae frequency. Waves are forced at the bottom of the domain, are periodic in the horizontal direction, and form a finite wave packet in the vertical. The results show that the wave packet forms a mean flow that is confined to the interface region that persists long after the wave packet has moved away. Large-amplitude waves are forced to break beneath the interface. (orig.)

DRI internal Wave Simulations

National Research Council Canada - National Science Library

Reynolds, Stephen A; Levine, Murray D

2005-01-01

.... A processing module is developed that takes profile estimates as input and uses numerically simulated linear internal wave displacements to create two-dimensional range-dependent sound speed fields...

Theoretical analysis and experimental study of oxygen transfer under regular and non-breaking waves

Institute of Scientific and Technical Information of China (English)

尹则高; 梁丙臣; 王乐

2013-01-01

The dissolved oxygen concentration is an important index of water quality, and the atmosphere is one of the important sources of the dissolved oxygen. In this paper, the mass conservation law and the dimensional analysis method are employed to study the oxygen transfer under regular and non-breaking waves, and a unified oxygen transfer coefficient equation is obtained with consi-deration of the effect of kinetic energy and wave period. An oxygen transfer experiment for the intermediate depth water wave is per-formed to measure the wave parameters and the dissolved oxygen concentration. The experimental data and the least squares method are used to determine the constant in the oxygen transfer coefficient equation. The experimental data and the previous reported data are also used to further validate the oxygen transfer coefficient, and the agreement is satisfactory. The unified equation shows that the oxygen transfer coefficient increases with the increase of a parameter coupled with the wave height and the wave length, but it de-creases with the increase of the wave period, which has a much greater influence on the oxygen transfer coefficient than the coupled parameter.

Modeling the SAR Signature of Nonlinear Internal Waves

National Research Council Canada - National Science Library

Lettvin, Ellen E

2008-01-01

Nonlinear Internal Waves are pervasive globally, particularly in coastal waters. The currents and displacements associated with internal waves influence acoustic propagation and underwater navigation, as well as ocean transport and mixing...

Collisional drag may lead to disappearance of wave-breaking phenomenon of lower hybrid oscillations

International Nuclear Information System (INIS)

Maity, Chandan; Chakrabarti, Nikhil

2013-01-01

The inhomogeneity in the magnetic field in a cold electron-ion non-dissipative homogeneous plasma leads to the breaking of lower hybrid modes via phase mixing phenomenon [Maity et al. Phys. Plasmas 19, 102302 (2012)]. In this work, we show that an inclusion of collisional drag force in fluid equations may lead to the disappearance of the wave-breaking phenomenon of lower hybrid oscillations. The nonlinear analysis in Lagrangian variables provides an expression for a critical value of damping rate, above which spikes in the plasma density profile may disappear. The critical damping rate depends on the perturbation and magnetic field inhomogeneity amplitudes as well as the ratio of the magnetic field inhomogeneity and perturbation scale lengths.

Massachusetts Bay - Internal wave packets digitized from SAR imagery

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...

The Record Los Angeles Heat Event of September 2010: 1. Synoptic-Scale-Meso-β-Scale Analyses of Interactive Planetary Wave Breaking, Terrain- and Coastal-Induced Circulations

Science.gov (United States)

Kaplan, Michael L.; Tilley, Jeffrey S.; Hatchett, Benjamin J.; Smith, Craig M.; Walston, Joshua M.; Shourd, Kacie N.; Lewis, John M.

2017-10-01

On 27 September 2010 the Los Angeles Civic Center reached its all-time record maximum temperature of 45°C before 1330 local daylight time with several other regional stations observing all-time record breaking heat early in that afternoon. This record event is associated with a general circulation pattern predisposed to hemispheric wave breaking. Three days before the event, wave breaking organizes complex terrain- and coastal-induced processes that lead to isentropic surface folding into the Los Angeles Basin. The first wave break occurs over the western two thirds of North America leading to trough elongation across the southwestern U.S. Collocated with this trough is an isentropic potential vorticity filament that is the locus of a thermally indirect circulation central to warming and associated thickness increases and ridging westward across the Great Basin. In response to this circulation, two subsynoptic wave breaks are triggered along the Pacific coast. The isentropic potential vorticity filament is coupled to the breaking waves and the interaction produces a subsynoptic low-pressure center and a deep vortex aloft over the southeastern California desert. This coupling leads to advection of an elevated mixed layer over Point Conception the night before the record-breaking heat that creates a coastally trapped low-pressure area southwest of Los Angeles. The two low-pressure centers create a low-level pressure gradient and east-southeasterly jet directed offshore over the Los Angeles Basin by sunrise on 27 September. This allows the advection of low-level warm air from the inland terrain toward the coastally trapped disturbance and descending circulation resulting in record heating.

28th International Symposium on Shock Waves

CERN Document Server

2012-01-01

The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.

The effect of breaking gravity waves on the dynamics and chemistry of the mesosphere and lower thermosphere (invited review)

Science.gov (United States)

Garcia, R. R.

1986-01-01

The influence of breaking gravity waves on the dynamics and chemical composition of the 60 to 110 km region is investigated with a two dimensional model that includes a parameterization of gravity wave momentum deposition and diffusion. The dynamical model is described by Garcia and Solomon (1983) and Solomon and Garcia (1983) and includes a complete chemical scheme for the mesosphere and lower thermosphere. The parameterization of Lindzen (1981) is used to calculate the momentum deposited and the turbulent diffusion produced by the gravity waves. It is found that wave momentum deposition drives a very vigorous mean meridional circulation, produces a very cold summer mesopause and reverse the zonal wind jets above about 85 km. The seasonal variation of the turbulent diffusion coefficient is consistent with the behavior of mesospheric turbulences inferred from MST radar echoes. The large degree of consistency between model results and various types of dynamical and chemical data supports very strongly the hypothesis that breaking gravity waves play a major role in determining the zonally-averaged dynamical and chemical structure of the 60 to 110 km region of the atmosphere.

Review of research in internal-wave and internal-tide deposits of China: Discussion

Directory of Open Access Journals (Sweden)

G. Shanmugam

2014-10-01

Full Text Available This discussion of a review article by [27], published in the Journal of Palaeogeography (2(1: 56– 65, is aimed at illustrating that interpretations of ten ancient examples in China and one in the central Appalachians (USA as deep-water deposits of internal waves and internal tides are unsustainable. This critical assessment is based on an in-depth evaluation of oceanographic and sedimentologic data on internal waves and internal tides derived from 332 print and online published works during 1838–January 2013, which include empirical data on the physical characteristics of modern internal waves and internal tides from 51 regions of the world’s oceans [108]. In addition, core and outcrop descriptions of deep-water strata from 35 case studies worldwide carried out by the author during 1974–2011, and a selected number of case studies published by other researchers are evaluated for identifying the sedimentological challenges associated with distinguishing types of bottom-current reworked sands in the ancient sedimentary record. The emerging conclusion is that any interpretation of ancient strata as deposits of internal waves and internal tides is premature.

Internal Ocean Waves

Science.gov (United States)

2006-01-01

Internal waves are waves that travel within the interior of a fluid. The waves propagate at the interface or boundary between two layers with sharp density differences, such as temperature. They occur wherever strong tides or currents and stratification occur in the neighborhood of irregular topography. They can propagate for several hundred kilometers. The ASTER false-color VNIR image off the island of Tsushima in the Korea Strait shows the signatures of several internal wave packets, indicating a northern propagation direction. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate. Size: 60 by 120 kilometers (37.2 by 74.4 miles) Location: 34.6 degrees North latitude, 129.5 degrees East longitude Orientation: North at top Image Data: ASTER bands 3, 2, and 1 Original Data Resolution: 90

Dynamic response of a riser under excitation of internal waves

Science.gov (United States)

Lou, Min; Yu, Chenglong; Chen, Peng

2015-12-01

In this paper, the dynamic response of a marine riser under excitation of internal waves is studied. With the linear approximation, the governing equation of internal waves is given. Based on the rigid-lid boundary condition assumption, the equation is solved by Thompson-Haskell method. Thus the velocity field of internal waves is obtained by the continuity equation. Combined with the modified Morison formula, using finite element method, the motion equation of riser is solved in time domain with Newmark-β method. The computation programs are compiled to solve the differential equations in time domain. Then we get the numerical results, including riser displacement and transfiguration. It is observed that the internal wave will result in circular shear flow, and the first two modes have a dominant effect on dynamic response of the marine riser. In the high mode, the response diminishes rapidly. In different modes of internal waves, the deformation of riser has different shapes, and the location of maximum displacement shifts. Studies on wave parameters indicate that the wave amplitude plays a considerable role in response displacement of riser, while the wave frequency contributes little. Nevertheless, the internal waves of high wave frequency will lead to a high-frequency oscillation of riser; it possibly gives rise to fatigue crack extension and partial fatigue failure.

Sheet flow measurements on a surf-zone sandbar under shoaling and breaking waves

Science.gov (United States)

Mieras, R.; Puleo, J. A.; Cox, D. T.; Anderson, D. L.; Kim, Y.; Hsu, T. J.

2016-02-01

A large-scale experiment to quantify sheet flow processes over a sandbar under varying levels of wave steepness was conducted in the wave flume at Oregon State University's O.H. Hinsdale Wave Research Laboratory. A fixed profile was constructed with concrete slabs anchored to the flume side walls, with the exception of the sandbar crest, where a steel pit was installed and filled with well-sorted sediment (d50 0.17 mm). This hybrid approach allowed for the isolation of small-scale bed response to large-scale wave forcing over the sandbar, where an array of sensors was positioned to measure hydrodynamic forcing and sediment response. Near-bed ( 0.08 m3/m3) were approximated using Conductivity Concentration Profilers. Test conditions consisted of a regular wave train with incident wave heights for individual runs ranging from 0.4 m to 0.6 m and incident wave periods from 5 s to 9 s, encompassing a variety of skewed and asymmetric wave shapes across the shoaling and breaking regimes. Ensemble-averaged sediment concentration profiles exhibit considerable variation across the different conditions. The largest variation in sheet layer thickness occurs beneath the wave crest, ranging from 30 grain diameters for 5 sec, 0.4 m waves, up to 80 grain diameters for 7 sec, 0.6 m waves. Furthermore, the initiation and duration of sheet flow relative to the wave period differs for each condition set. It is likely that more than one mechanism plays a role in determining the aforementioned sheet layer characteristics. In the present work, we focus on the relative magnitude and phase of the near-bed flow acceleration and shear stress in determining the characteristics of the sheet layer.

A Multiscale Nested Modeling Framework to Simulate the Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves

Science.gov (United States)

2015-09-30

Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves Lian Shen St. Anthony Falls Laboratory and Department of Mechanical...on studying surface gravity wave evolution and spectrum in the presence of surface currents caused by strongly nonlinear internal solitary waves...interaction of surface and internal gravity waves in the South China Sea. We will seek answers to the following questions: 1) How does the wind-wave

Stratospheric Influence on Summer Monsoon and Associated Planetary Wave Breaking and Mixing in the Subtropical Tropopause Region

Science.gov (United States)

Lubis, S. W.; Nakamura, N.

2017-12-01

Previous studies have shown that the monsoonal circulation plays an important role in planetary wave breaking (PWB). The highest frequency of breaking events occurs just downstream (east) of the monsoon region in summer. PWB induces mixing of potential vorticity (PV) and hence, alter the horizontal mixing in the atmosphere. Here, the authors hypothesize that the stratospheric easterlies in the boreal summer also play a significant role in the PWB and mixing associated with the summer monsoon. If the stratospheric winds were westerly in boreal summer, the frequency of PWB would be decreased due to more waves penetrating in the stratosphere, resulting in less horizontal PWB and thus reduced mixing in the subtropical tropopause region. The hypothesis is examined by using a set of idealized moist GFDL simulations. The monsoon circulation is produced by adding a land-sea contrast with a Gaussian-shaped mountains positioned in the midlatitudes. Other key ingredients for the monsoon, including albedo, oceanic warm pool, and Q-flux, were also ideally imposed in all simulations. Our control simulation produces a summer monsoon-like circulation similar to the observation. In particular, the thermally forced monsoonal circulation forms a prominent closed upper-level anticyclone that dominates the summertime upper-level flow. Associated with this circulation is an upward-bulging tropopause that forms a large reservoir of anomalously low PV. Consistent with previous studies, the well-defined tropospheric jet lies just poleward of the upper-level anticyclone, and acts as a dynamical barrier between the low-PV reservoir over the monsoonal region and the high-PV reservoir in the extratropics. This barrier disappears just northeast of the monsoon area in the jet exit region, allowing more quasi-planetary waves to break in this region. Repetitive wave breaking further weakens the PV gradient, leading to the formation of the surf zone and stronger mixing in this region. To quantify

Simulating Bubble Plumes from Breaking Waves with a Forced-Air Venturi

Science.gov (United States)

Long, M. S.; Keene, W. C.; Maben, J. R.; Chang, R. Y. W.; Duplessis, P.; Kieber, D. J.; Beaupre, S. R.; Frossard, A. A.; Kinsey, J. D.; Zhu, Y.; Lu, X.; Bisgrove, J.

2017-12-01

It has been hypothesized that the size distribution of bubbles in subsurface seawater is a major factor that modulates the corresponding size distribution of primary marine aerosol (PMA) generated when those bubbles burst at the air-water interface. A primary physical control of the bubble size distribution produced by wave breaking is the associated turbulence that disintegrates larger bubbles into smaller ones. This leads to two characteristic features of bubble size distributions: (1) the Hinze scale which reflects a bubble size above which disintegration is possible based on turbulence intensity and (2) the slopes of log-linear regressions of the size distribution on either side of the Hinze scale that indicate the state of plume evolution or age. A Venturi with tunable seawater and forced air flow rates was designed and deployed in an artificial PMA generator to produce bubble plumes representative of breaking waves. This approach provides direct control of turbulence intensity and, thus, the resulting bubble size distribution characterizable by observations of the Hinze scale and the simulated plume age over a range of known air detrainment rates. Evaluation of performance in different seawater types over the western North Atlantic demonstrated that the Venturi produced bubble plumes with parameter values that bracket the range of those observed in laboratory and field experiments. Specifically, the seawater flow rate modulated the value of the Hinze scale while the forced-air flow rate modulated the plume age parameters. Results indicate that the size distribution of sub-surface bubbles within the generator did not significantly modulate the corresponding number size distribution of PMA produced via bubble bursting.

Pre-study of dynamic loads on the internals caused by a large pipe break in a BWR; Foerstudie av stroemningsinducerade laster paa interndelar vid brott i huvudcirkulationskretsarna i BWR

Energy Technology Data Exchange (ETDEWEB)

Marcinkiewicz, Jerzy; Lindgren, Anders [Det Norske Veritas Nuclear Technology AB, Stockholm (Sweden)

2002-12-01

Det Norske Veritas Nuclear Technology has performed a literature study of dynamic load on a BWR (Boiling Water Reactor) internals caused by a large pipe break. The goal of the study was to improve the knowledge about the physics of phenomena occurring in the RPV (Reactor Pressure Vessel) after pipe break in the main circulation system and also to make a review of calculation methods, models and computer programs including their capabilities when calculating the dynamic loads. The report presents description of relevant parts of a BWR, initial and boundary conditions, and phenomena determining the loads - rapid depressurization and propagation of pressure wave (including none-equilibrium). Furthermore, the report generally describes possible methodologies for calculating the dynamic loads on internals after the pipe break and the experiences from calculations the dynamic loads with different methods (computer programs) including comparisons with experimental data. Fluid-Structure Interaction methodology and its importance for calculation of dynamic loads on reactor internals is discussed based on experimental data. A very intensive research program for studying and calculating the dynamic loads on internals after pipe breaks has been performed in USA and Germany during the seventies and the eighties. Several computer programs have been developed and a number of large-scale experiments have been performed to calibrate the calculation methods. In spite of the fact that all experiments were performed for PWR several experiences should be valid also for BWR. These experiences, connected mainly to capabilities of computer programs calculating dynamic loads, are discussed in the report.

Modification of AMD wave functions and application to the breaking of the N=20 magic number

International Nuclear Information System (INIS)

Kimura, Masaaki; Horiuchi, Hisashi

2001-01-01

By using the deformed Gaussian instead of the spherical one, we have modified the AMD (Antisymmetrized Molecular Dynamics) wave functions. The calculation results with this modified AMD shows the drastic improvement of the deformation properties of Mg isotopes. This improvement means that this new version of AMD can treat the deformation of mean field properly than before and the deformation of mean field is important in Mg isotopes. With this new version of AMD, we have also calculated 32Mg in which the breaking of magic number N=20 is experimentally known. In this nucleus, β-energy surface is also drastically changed by the modification AMD wave function. Our results show that this nucleus is indeed deformed and neutron's 2p2h state is dominant in its ground state. This ground state reproduces the experimental data and shows the breaking of the magic number N=20 clearly. Additionally, near the ground state, there is also very interesting state which has neutron's 4p4h structure and shows parity violating density distribution and cluster-like nature. (author)

Modification of AMD wave functions and application to the breaking of the N=20 magic number

Energy Technology Data Exchange (ETDEWEB)

Kimura, Masaaki; Horiuchi, Hisashi [Kyoto Univ. (Japan). Dept. of Physics

2001-09-01

By using the deformed Gaussian instead of the spherical one, we have modified the AMD (Antisymmetrized Molecular Dynamics) wave functions. The calculation results with this modified AMD shows the drastic improvement of the deformation properties of Mg isotopes. This improvement means that this new version of AMD can treat the deformation of mean field properly than before and the deformation of mean field is important in Mg isotopes. With this new version of AMD, we have also calculated 32Mg in which the breaking of magic number N=20 is experimentally known. In this nucleus, {beta}-energy surface is also drastically changed by the modification AMD wave function. Our results show that this nucleus is indeed deformed and neutron's 2p2h state is dominant in its ground state. This ground state reproduces the experimental data and shows the breaking of the magic number N=20 clearly. Additionally, near the ground state, there is also very interesting state which has neutron's 4p4h structure and shows parity violating density distribution and cluster-like nature. (author)

Nearshore bars and the break-point hypothesis

Science.gov (United States)

Sallenger, A.H.; Howd, P.A.

1989-01-01

The set of hypotheses calling for bar formation at the break point was tested with field data. During two different experiments, waves were measured across the surf zone coincident with the development of a nearshore bar. We use a criterion, based on the wave height to depth ratio, to determine the offshore limit of the inner surf zone. During the first experiment, the bar became better developed and migrated offshore while remaining well within the inner surf zone. During the second experiment, the surf zone was narrower and we cannot rule out the possibility of break point processes contributing to bar development. We conclude that bars are not necessarily coupled with the break point and can become better developed and migrate offshore while being in the inner surf zone landward from initial wave breaking in the outer surf zone. ?? 1989.

Internal wave patterns in enclosed density-stratified and rotating fluids

NARCIS (Netherlands)

Manders, A.M.A.

2003-01-01

Stratified fluids support internal waves, which propagate obliquely through the fluid. The angle with respectto the stratification direction is contrained: it is purely determined by the wave frequency and the strength of the density stratification (internal gravity waves) or the rotation rate

International Standard Problems and Small Break Loss-Of-Coolant Accident (SBLOCA)

International Nuclear Information System (INIS)

Aksan, N.

2008-01-01

Best-estimate thermalhydraulic system codes are widely used to perform safety and licensing analyses of nuclear power plants and also used in the design of advance reactors. Evaluation of the capabilities and the performance of these codes can be accomplished by comparing the code predictions with measured experimental data obtained on different test facilities. In this respect, parallel to other national and international programs, OECD/Nea (OECD Nuclear Energy Agency) Committee on the Safety of Nuclear Installations (CSNI) has promoted, over the last twenty-nine years some forty-eight International Standard Problems (ISPs). These ISPs were performed in different fields as in-vessel thermalhydraulic behaviour, fuel behaviour under accident conditions, fission product release and transport, core/concrete interactions, hydrogen distribution and mixing, containment thermalhydraulic behaviour. 80% of these ISPs were related to the working domain of Principal Working Group no. 2 on Coolant System Behaviour (PWG2). The ISPs have been one of the major PWG2 activities for many years. The individual ISP comparison reports include the analysis and conclusions of the specific ISP exercises. A global review and synthesis on the contribution that ISPs have made to address nuclear reactor safety issues was initiated by CSNI-PWG2 and an overview on the subject of small break LOCA ISP's is given in this paper based on a report prepared by a CSNI-PWG2 writing group. In addition, the relevance of small break LOCA in a PWR with relation to nuclear reactor safety and the reorientation of the reactor safety program after TMI-2 accident, specifically small break LOCA, are shortly summarized. Five small break LOCA related ISP's are considered, since these were used for the assessment of the advanced best-estimate codes. The considered ISP's deal with the phenomenon typical of small break LOCAs in Western design PWRs. The experiments in four integral test facilities, LOBI, SPES, BETHSY

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

OpenAIRE

X. Liu; X. Liu; J. Xu; H.-L. Liu; J. Yue; W. Yuan

2014-01-01

Using a fully nonlinear two-dimensional (2-D) numerical model, we simulated gravity waves (GWs) breaking and their contributions to the formation of large winds and wind shears in the mesosphere and lower thermosphere (MLT). An eddy diffusion coefficient is used in the 2-D numerical model to parameterize realistic turbulent mixing. Our study shows that the momentum deposited by breaking GWs accelerates the mean wind. The resultant large background wind increases the GW's app...

Size Distribution and Dispersion of Droplets Generated by Impingement of Breaking Waves on Oil Slicks

Science.gov (United States)

Li, C.; Miller, J.; Wang, J.; Koley, S. S.; Katz, J.

2017-10-01

This laboratory experimental study investigates the temporal evolution of the size distribution of subsurface oil droplets generated as breaking waves entrain oil slicks. The measurements are performed for varying wave energy, as well as large variations in oil viscosity and oil-water interfacial tension, the latter achieved by premixing the oil with dispersant. In situ measurements using digital inline holography at two magnifications are applied for measuring the droplet sizes and Particle Image Velocimetry (PIV) for determining the temporal evolution of turbulence after wave breaking. All early (2-10 s) size distributions have two distinct size ranges with different slopes. For low dispersant to oil ratios (DOR), the transition between them could be predicted based on a turbulent Weber (We) number in the 2-4 range, suggesting that turbulence plays an important role. For smaller droplets, all the number size distributions have power of about -2.1, and for larger droplets, the power decreases well below -3. The measured steepening of the size distribution over time is predicted by a simple model involving buoyant rise and turbulence dispersion. Conversely, for DOR 1:100 and 1:25 oils, the diameter of slope transition decreases from ˜1 mm to 46 and 14 µm, respectively, much faster than the We-based prediction, and the size distribution steepens with increasing DOR. Furthermore, the concentration of micron-sized droplets of DOR 1:25 oil increases for the first 10 min after entrainment. These phenomena are presumably caused by the observed formation and breakup oil microthreads associated with tip streaming.

30th International Symposium on Shock Waves

CERN Document Server

Sadot, Oren; Igra, Ozer

2017-01-01

These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

Suppression of beam-break-up in a standing wave free electron laser two-beam accelerator

International Nuclear Information System (INIS)

Li, H.; Kim, J.S.

1994-03-01

Various schemes are examined in this study on the suppression of beam break-up (BBU) in a standing wave free electron laser two-beam accelerator (SWFEL/TBA). Two schemes are found to be not only able to effectively suppress the BBU but at the same time have minimum effect on the microwave generation process inside the SWFEL cavities. One is making the cavity-iris junction sufficiently gradual and the other is stagger-tuning the cavities

Internally driven inertial waves in geodynamo simulations

Science.gov (United States)

Ranjan, A.; Davidson, P. A.; Christensen, U. R.; Wicht, J.

2018-05-01

Inertial waves are oscillations in a rotating fluid, such as the Earth's outer core, which result from the restoring action of the Coriolis force. In an earlier work, it was argued by Davidson that inertial waves launched near the equatorial regions could be important for the α2 dynamo mechanism, as they can maintain a helicity distribution which is negative (positive) in the north (south). Here, we identify such internally driven inertial waves, triggered by buoyant anomalies in the equatorial regions in a strongly forced geodynamo simulation. Using the time derivative of vertical velocity, ∂uz/∂t, as a diagnostic for traveling wave fronts, we find that the horizontal movement in the buoyancy field near the equator is well correlated with a corresponding movement of the fluid far from the equator. Moreover, the azimuthally averaged spectrum of ∂uz/∂t lies in the inertial wave frequency range. We also test the dispersion properties of the waves by computing the spectral energy as a function of frequency, ϖ, and the dispersion angle, θ. Our results suggest that the columnar flow in the rotation-dominated core, which is an important ingredient for the maintenance of a dipolar magnetic field, is maintained despite the chaotic evolution of the buoyancy field on a fast timescale by internally driven inertial waves.

Analytical and numerical investigation of nonlinear internal gravity waves

Directory of Open Access Journals (Sweden)

S. P. Kshevetskii

2001-01-01

Full Text Available The propagation of long, weakly nonlinear internal waves in a stratified gas is studied. Hydrodynamic equations for an ideal fluid with the perfect gas law describe the atmospheric gas behaviour. If we neglect the term Ͽ dw/dt (product of the density and vertical acceleration, we come to a so-called quasistatic model, while we name the full hydro-dynamic model as a nonquasistatic one. Both quasistatic and nonquasistatic models are used for wave simulation and the models are compared among themselves. It is shown that a smooth classical solution of a nonlinear quasistatic problem does not exist for all t because a gradient catastrophe of non-linear internal waves occurs. To overcome this difficulty, we search for the solution of the quasistatic problem in terms of a generalised function theory as a limit of special regularised equations containing some additional dissipation term when the dissipation factor vanishes. It is shown that such solutions of the quasistatic problem qualitatively differ from solutions of a nonquasistatic nature. It is explained by the fact that in a nonquasistatic model the vertical acceleration term plays the role of a regularizator with respect to a quasistatic model, while the solution qualitatively depends on the regularizator used. The numerical models are compared with some analytical results. Within the framework of the analytical model, any internal wave is described as a system of wave modes; each wave mode interacts with others due to equation non-linearity. In the principal order of a perturbation theory, each wave mode is described by some equation of a KdV type. The analytical model reveals that, in a nonquasistatic model, an internal wave should disintegrate into solitons. The time of wave disintegration into solitons, the scales and amount of solitons generated are important characteristics of the non-linear process; they are found with the help of analytical and numerical investigations. Satisfactory

Lagrangian transport in poleward breaking Rossby waves in the North Atlantic - Europe tropopause region

Energy Technology Data Exchange (ETDEWEB)

Bartels, J; Peters, D [Rostock Univ. (Germany). Inst. fuer Atmosphaerenphysik

1998-12-31

The poleward advection of upper-tropospheric air is investigated for poleward Rossby wave breaking events. During boreal winter months the isentropic deformations of the tropopause are examined using maps of Ertel`s potential vorticity (EPV) and contour advection (CA) calculations. The role of ambient baro-tropic flow is further examined by idealized numerical models. In the vicinity of the tropopause the characteristic Lagrangian transport of air masses for ECMWF-analysis data are compared with high resolution (T106) ECHAM4 experiments. (author) 3 refs.

Lagrangian transport in poleward breaking Rossby waves in the North Atlantic - Europe tropopause region

Energy Technology Data Exchange (ETDEWEB)

Bartels, J.; Peters, D. [Rostock Univ. (Germany). Inst. fuer Atmosphaerenphysik

1997-12-31

The poleward advection of upper-tropospheric air is investigated for poleward Rossby wave breaking events. During boreal winter months the isentropic deformations of the tropopause are examined using maps of Ertel`s potential vorticity (EPV) and contour advection (CA) calculations. The role of ambient baro-tropic flow is further examined by idealized numerical models. In the vicinity of the tropopause the characteristic Lagrangian transport of air masses for ECMWF-analysis data are compared with high resolution (T106) ECHAM4 experiments. (author) 3 refs.

Resolving high-frequency internal waves generated at an isolated coral atoll using an unstructured grid ocean model

Science.gov (United States)

Rayson, Matthew D.; Ivey, Gregory N.; Jones, Nicole L.; Fringer, Oliver B.

2018-02-01

We apply the unstructured grid hydrodynamic model SUNTANS to investigate the internal wave dynamics around Scott Reef, Western Australia, an isolated coral reef atoll located on the edge of the continental shelf in water depths of 500,m and more. The atoll is subject to strong semi-diurnal tidal forcing and consists of two relatively shallow lagoons separated by a 500 m deep, 2 km wide and 15 km long channel. We focus on the dynamics in this channel as the internal tide-driven flow and resulting mixing is thought to be a key mechanism controlling heat and nutrient fluxes into the reef lagoons. We use an unstructured grid to discretise the domain and capture both the complex topography and the range of internal wave length scales in the channel flow. The model internal wave field shows super-tidal frequency lee waves generated by the combination of the steep channel topography and strong tidal flow. We evaluate the model performance using observations of velocity and temperature from two through water-column moorings in the channel separating the two reefs. Three different global ocean state estimate datasets (global HYCOM, CSIRO Bluelink, CSIRO climatology atlas) were used to provide the model initial and boundary conditions, and the model outputs from each were evaluated against the field observations. The scenario incorporating the CSIRO Bluelink data performed best in terms of through-water column Murphy skill scores of water temperature and eastward velocity variability in the channel. The model captures the observed vertical structure of the tidal (M2) and super-tidal (M4) frequency temperature and velocity oscillations. The model also predicts the direction and magnitude of the M2 internal tide energy flux. An energy analysis reveals a net convergence of the M2 energy flux and a divergence of the M4 energy flux in the channel, indicating the channel is a region of either energy transfer to higher frequencies or energy loss to dissipation. This conclusion is

A third-order KdV solution for internal solitary waves and its application in the numerical wave tank

Directory of Open Access Journals (Sweden)

Qicheng Meng

2016-04-01

Full Text Available A third-order KdV solution to the internal solitary wave is derived by a new method based on the weakly nonlinear assumptions in a rigid-lid two-layer system. The solution corrects an error by Mirie and Su (1984. A two-dimensional numerical wave tank has been established with the help of the open source CFD library OpenFOAM and the third-party software waves2Foam. Various analytical solutions, including the first-order to third-order KdV solutions, the eKdV solution and the MCC solution, have been used to initialise the flow fields in the CFD simulations of internal solitary waves. Two groups including 11 numerical cases have been carried out. In the same group, the initial wave amplitudes are the same but the implemented analytical solutions are different. The simulated wave profiles at different moments have been presented. The relative errors in terms of the wave amplitude between the last time step and the initial input have been analysed quantitatively. It is found that the third-order KdV solution results in the most stable internal solitary wave in the numerical wave tank for both small-amplitude and finite-amplitude cases. The finding is significant for the further simulations involving internal solitary waves.

Internal wave-mediated shading causes frequent vertical migrations in fishes

KAUST Repository

Kaartvedt, Stein; Klevjer, TA; Aksnes, Dag L.

2012-01-01

We provide evidence that internal waves cause frequent vertical migrations (FVM) in fishes. Acoustic data from the Benguela Current revealed that pelagic scattering layers of fish below ~140 m moved in opposite phases to internal waves, ascending

A two-dimensional analysis of the sensitivity of a pulse first break to wave speed contrast on a scale below the resolution length of ray tomography.

Science.gov (United States)

Willey, Carson L; Simonetti, Francesco

2016-06-01

Mapping the speed of mechanical waves traveling inside a medium is a topic of great interest across many fields from geoscience to medical diagnostics. Much work has been done to characterize the fidelity with which the geometrical features of the medium can be reconstructed and multiple resolution criteria have been proposed depending on the wave-matter interaction model used to decode the wave speed map from scattering measurements. However, these criteria do not define the accuracy with which the wave speed values can be reconstructed. Using two-dimensional simulations, it is shown that the first-arrival traveltime predicted by ray theory can be an accurate representation of the arrival of a pulse first break even in the presence of diffraction and other phenomena that are not accounted for by ray theory. As a result, ray-based tomographic inversions can yield accurate wave speed estimations also when the size of a sound speed anomaly is smaller than the resolution length of the inversion method provided that traveltimes are estimated from the signal first break. This increased sensitivity however renders the inversion more susceptible to noise since the amplitude of the signal around the first break is typically low especially when three-dimensional anomalies are considered.

Novel Methods for Optically Measuring Whitecaps Under Natural Wave Breaking Conditions in the Southern Ocean

Science.gov (United States)

Randolph, K. L.; Dierssen, H. M.; Cifuentes-Lorenzen, A.; Balch, W. M.; Monahan, E. C.; Zappa, C. J.; Drapeau, D.; Bowler, B.

2016-02-01

Breaking waves on the ocean surface mark areas of significant importance to air-sea flux estimates of gas, aerosols, and heat. Traditional methods of measuring whitecap coverage using digital photography can miss features that are small in size or do not show high enough contrast to the background. The geometry of the images collected captures the near surface, bright manifestations of the whitecap feature and miss a portion of the bubble plume that is responsible for the production of sea salt aerosols and the transfer of lower solubility gases. Here, a novel method for accurately measuring both the fractional coverage of whitecaps and the intensity and decay rate of whitecap events using above water radiometry is presented. The methodology was developed using data collected during the austral summer in the Atlantic sector of the Southern Ocean under a large range of wind (speeds of 1 to 15 m s-1) and wave (significant wave heights 2 to 8 m) conditions as part of the Southern Ocean Gas Exchange experiment. Whitecap metrics were retrieved by employing a magnitude threshold based on the interquartile range of the radiance or reflectance signal for a single channel (411 nm) after a baseline removal, determined using a moving minimum/maximum filter. Breaking intensity and decay rate metrics were produced from the integration of, and the exponential fit to, radiance or reflectance over the lifetime of the whitecap. When compared to fractional whitecap coverage measurements obtained from high resolution digital images, radiometric estimates were consistently higher because they capture more of the decaying bubble plume area that is difficult to detect with photography. Radiometrically-retrieved whitecap measurements are presented in the context of concurrently measured meteorological (e.g., wind speed) and oceanographic (e.g., wave) data. The optimal fit of the radiometrically estimated whitecap coverage to the instantaneous wind speed, determined using ordinary least

Internal wave energy radiated from a turbulent mixed layer

Energy Technology Data Exchange (ETDEWEB)

Munroe, James R., E-mail: jmunroe@mun.ca [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada); Sutherland, Bruce R., E-mail: bsuther@ualberta.ca [Departments of Physics and Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

2014-09-15

We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy density. The internal waves are measured using synthetic schlieren to determine their amplitudes, frequencies, and energy density. We also perform fully nonlinear numerical simulations restricted to two dimensions but in a horizontally periodic domain. These clearly demonstrate that internal waves are generated by transient eddies at the integral length scale of turbulence and which translate with the background shear along the base of the mixed layer. In both experiments and simulations we find that the energy density of the generated waves is 1%–3% of the turbulent kinetic energy density of the turbulent layer.

Jet simulations and gamma-ray burst afterglow jet breaks

NARCIS (Netherlands)

van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

2011-01-01

The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

Jet simulations and gamma-ray burst afterglow jet breaks

NARCIS (Netherlands)

van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

2010-01-01

The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

Parity breaking signatures from a Chern-Simons coupling during inflation: the case of non-Gaussian gravitational waves

Energy Technology Data Exchange (ETDEWEB)

Bartolo, Nicola; Orlando, Giorgio, E-mail: nicola.bartolo@pd.infn.it, E-mail: giorgio.orlando@phd.unipd.it [Dipartimento di Fisica e Astronomia ' ' G. Galilei' , Università degli Studi di Padova, via Marzolo 8, 35131, Padova (Italy)

2017-07-01

Considering high-energy modifications of Einstein gravity during inflation is an interesting issue. We can constrain the strength of the new gravitational terms through observations of inflationary imprints in the actual universe. In this paper we analyze the effects on slow-roll models due to a Chern-Simons term coupled to the inflaton field through a generic coupling function f (φ). A well known result is the polarization of primordial gravitational waves (PGW) into left and right eigenstates, as a consequence of parity breaking. In such a scenario the modifications to the power spectrum of PGW are suppressed under the conditions that allow to avoid the production of ghost gravitons at a certain energy scale, the so-called Chern-Simons mass M {sub CS}. In general it has been recently pointed out that there is very little hope to efficiently constrain chirality of PGW on the basis solely of two-point statistics from future CMB data, even in the most optimistic cases. Thus we search if significant parity breaking signatures can arise at least in the bispectrum statistics. We find that the tensor-tensor-scalar bispectra ( γ γ ζ ) for each polarization state are the only ones that are not suppressed. Their amplitude, setting the level of parity breaking during inflation, is proportional to the second derivative of the coupling function f (φ) and they turn out to be maximum in the squeezed limit. We comment on the squeezed-limit consistency relation arising in the case of chiral gravitational waves, and on possible observables to constrain these signatures.

Power Difference in Spectrum of Sound Radiation before and after Break of Phantom by Piezoelectric Extracorporeal Shock Wave Lithotriptor

Science.gov (United States)

Kanai, Hiroshi; Jang, Yun-Seok; Chubachi, Noriyoshi; Tanahashi, Yoshikatsu

1994-05-01

This paper investigates the difference in the spectrum of sound radiated before and after the break of a phantom at a focal point of the piezoelectric extracorporeal shock wave lithotriptor (ESWL) in order to identify the break time or to examine whether a calculus exists exactly at the focal point or not. From the preliminary experiments using a piece of chalk as a phantom of a calculus to measure the sound radiated when impact is applied to the chalk by an impact hammer, it is found that the bending vibration component of the vibration is exhibited in the spectrum of sound. However, for small-sized chalk shorter than 3 cm, the peak frequency of the bending vibration is higher than 20 kHz. From the experiments using a piezoeletric ESWL, it is found that there is clear difference in the power spectra among the sound radiated before the break, that radiated just after the break in the breaking process, and that radiated when the chalk does not exist at the focal point of the ESWL. These characteristics will be effective for the examination of the existence of the calculus at the focal point.

THE WAVE INTERACTION OF HEAVY BREAKS IN THE WATER WITH ELASTIC BARRIER

Directory of Open Access Journals (Sweden)

Ivanchenko G.M.

2014-06-01

Full Text Available Transformation of underwater shock wave spherical front geometry and chauge of impulse carried by it at interaction witu elastic shield is numerically investigated witu the use of zero approximation of ray technique. It is established, that in the vicinity of spots of total internal reflection in the plane interface between water and elastic body the additional internal stresses tend to infinity.

On the imprint of surfactant-driven stabilization of laboratory breaking wave foam with comparison to oceanic whitecaps

Science.gov (United States)

Callaghan, A. H.; Deane, G. B.; Stokes, M. D.

2017-08-01

Surfactants are ubiquitous in the global oceans: they help form the materially-distinct sea surface microlayer (SML) across which global ocean-atmosphere exchanges take place, and they reside on the surfaces of bubbles and whitecap foam cells prolonging their lifetime thus altering ocean albedo. Despite their importance, the occurrence, spatial distribution, and composition of surfactants within the upper ocean and the SML remains under-characterized during conditions of vigorous wave breaking when in-situ sampling methods are difficult to implement. Additionally, no quantitative framework exists to evaluate the importance of surfactant activity on ocean whitecap foam coverage estimates. Here we use individual laboratory breaking waves generated in filtered seawater and seawater with added soluble surfactant to identify the imprint of surfactant activity in whitecap foam evolution. The data show a distinct surfactant imprint in the decay phase of foam evolution. The area-time-integral of foam evolution is used to develop a time-varying stabilization function, ϕ>(t>) and a stabilization factor, Θ, which can be used to identify and quantify the extent of this surfactant imprint for individual breaking waves. The approach is then applied to wind-driven oceanic whitecaps, and the laboratory and ocean Θ distributions overlap. It is proposed that whitecap foam evolution may be used to determine the occurrence and extent of oceanic surfactant activity to complement traditional in-situ techniques and extend measurement capabilities to more severe sea states occurring at wind speeds in excess of about 10 m/s. The analysis procedure also provides a framework to assess surfactant-driven variability within and between whitecap coverage data sets.Plain Language SummaryThe foam patches made by breaking waves, also known as "whitecaps", are an important source of marine sea spray, which impacts weather and climate through the formation of cloud drops and ice. Sea spray

Enhanced breaking of heavy quark spin symmetry

Energy Technology Data Exchange (ETDEWEB)

Guo, Feng-Kun, E-mail: fkguo@hiskp.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Meißner, Ulf-G., E-mail: meissner@hiskp.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Shen, Cheng-Ping, E-mail: shencp@ihep.ac.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)

2014-11-10

Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of O(Λ{sub QCD}/m{sub Q}), with Λ{sub QCD} the scale of QCD and m{sub Q} the heavy quark mass. In this paper, we will show that a small S- and D-wave mixing in the wave function of the heavy quarkonium could induce a large breaking in the ratios of partial decay widths. As an example, we consider the decays of the ϒ(10860) into the χ{sub bJ}ω(J=0,1,2), which were recently measured by the Belle Collaboration. These decays exhibit a huge breaking of the spin symmetry relation were the ϒ(10860) a pure 5S bottomonium state. We propose that this could be a consequence of a mixing of the S-wave and D-wave components in the ϒ(10860). Prediction on the ratio Γ(ϒ(10860)→χ{sub b0}ω)/Γ(ϒ(10860)→χ{sub b2}ω) is presented assuming that the decay of the D-wave component is dominated by the coupled-channel effects.

Breaking Out of the Local: International dimensions of science shops

Directory of Open Access Journals (Sweden)

Caspar DeBok

2008-09-01

Full Text Available In this article we want to give an overview of the international dimension and the interest of the European Union (EU in the concept of Science Shops. The European Commission (EC manages the day-to-day business by initiating and implementing EU policies and spending EU funds. The EC support for Science Shops has been an important factor for the international interest and progress of the Science Shop movement. This article will not give detailed information about daily routines of a Science Shop. Detailed information about the Science Shop concept can be found at the Living Knowledge website (www.livingknowledge.org. Living Knowledge represents the international Science Shop Network. In this article international developments of the Science Shop Network, like the project TRAMS, and Science Shop backgrounds will be linked with past and new EU policies like the EU 7th Framework Programme for Research. It shows how community-based research does not only have a local dimension. The international Science Shop activities show the strengths of international cooperation to break out of the local and to bring local issues on the international agenda. Detailed information about the Science Shop concept and daily routines of a Science Shop can be found at the Living Knowledge website (www.livingknowledge.org, e.g. at the FAQ section and in the toolbox.

Incident wave, infragravity wave, and non-linear low-frequency bore evolution across fringing coral reefs

Science.gov (United States)

Storlazzi, C. D.; Griffioen, D.; Cheriton, O. M.

2016-12-01

Coral reefs have been shown to significantly attenuate incident wave energy and thus provide protection for 100s of millions of people globally. To better constrain wave dynamics and wave-driven water levels over fringing coral reefs, a 4-month deployment of wave and tide gauges was conducted across two shore-normal transects on Roi-Namur Island and two transects on Kwajalein Island in the Republic of the Marshall Islands. At all locations, although incident wave (periods 250 s) heights on the outer reef flat just inshore of the zone of wave breaking, the infragravity wave heights generally equaled the incident wave heights by the middle of the reef flat and exceeded the incident wave heights on the inner reef flat by the shoreline. The infragravity waves generally were asymmetric, positively skewed, bore-like forms with incident-band waves riding the infragravity wave crest at the head of the bore; these wave packets have similar structure to high-frequency internal waves on an internal wave bore. Bore height was shown to scale with water depth, offshore wave height, and offshore wave period. For a given tidal elevation, with increasing offshore wave heights, such bores occurred more frequently on the middle reef flat, whereas they occurred less frequently on the inner reef flat. Skewed, asymmetric waves are known to drive large gradients in velocity and shear stress that can transport material onshore. Thus, a better understanding of these low-frequency, energetic bores on reef flats is critical to forecasting how coral reef-lined coasts may respond to sea-level rise and climate change.

Study of internal wave generation by tide-topography interaction; Lecture by the member awarded the Okada Prize of the Oceanographical Society of Japan for 1989. Choryu niyoru naibuha no hassei kiko ni kansuru kenkyu; 1989 nendo Nippon kaiyo gakkai Okadasho jusho kinen koen

Energy Technology Data Exchange (ETDEWEB)

Hibiya, T. (Univ. of Tokyo (Japan). Earthquake Research Inst.)

1990-02-25

With regard to internal waves under strong tidal flows generated in the Amakusanada, Kyushu, the Canadian West Coast Region and the U.S. Eastern Coast Region, this study explains the theory of their generation mechanism showing the examples of its applicayion to the actual maritime regions, then by developing this theory, discusses the role of its vertical shear effect in the generation process of internal waves in case where the stationary two layer alternative flow lies on top of a strong tidal flow like the inside of straits and fjords, etc.. Furthermore, it clarifies the effect of the vertical mixing on the seawater alternating process inside and outside of the fjord taking place on the both sides of the above mixing when such a vertical mixing is caused by breaking waves of the internal tidal flows over a sill in the fjord, as an example of an important role taken by the internal waves with large wave heights thus generated. 28 refs., 12 figs.

Identification and modeling of internal waves

Digital Repository Service at National Institute of Oceanography (India)

Murty, T.V.R.; Sadhuram, Y.; Rao, M.M.M.; SujithKumar, S.; Maneesha, K.; Sandhya, K.S.; Prakash, S.S.; Chandramouli, P.; Murthy, K.S.R.

Analyses of Internal Wave (IW) signatures by insitu observations off Visakhapatnam have been presented to study the impact of IWs on acoustic field. Temperature data were collected for 44 hours off Visakhapatnam (17° 26.46’N and 83° 31.20’E...

Internal wave-mediated shading causes frequent vertical migrations in fishes

KAUST Repository

Kaartvedt, Stein

2012-04-25

We provide evidence that internal waves cause frequent vertical migrations (FVM) in fishes. Acoustic data from the Benguela Current revealed that pelagic scattering layers of fish below ~140 m moved in opposite phases to internal waves, ascending ~20 m towards the wave trough and descending from the wave crest. At the trough, the downward displacement of upper waters and the upward migration of fish created an overlapping zone. Near-bottom fish correspondingly left the benthic boundary zone at the wave trough, ascending into an acoustic scattering layer likely consisting of zooplankton and then descending to the benthic boundary zone at the wave crest. We suggest that this vertical fish migration is a response to fluctuations in light intensity of 3 to 4 orders of magnitude caused by shading from a turbid surface layer that had chlorophyll a values of 3 to 4 mg m−3 and varied in thickness from ~15 to 50 m at a temporal scale corresponding to the internal wave period (30 min). This migration frequency thus is much higher than that of the common and widespread light-associated diel vertical migration. Vertical movements affect prey encounters, growth, and survival. We hypothesize that FVM increase the likelihood of prey encounters and the time for safe visual foraging among planktivorous fish, thereby contributing to efficient trophic transfer in major upwelling areas.

Breaking antidunes: Cyclic behavior due to hysteresis

DEFF Research Database (Denmark)

Deigaard, Rolf

2006-01-01

The cyclic behavior of breaking antidunes (growth, breaking of surface wave, obliteration) is investigated by use of a numerical model. The model includes the transition between supercritical and transcritical flow. As the antidune grows the flow becomes transcritical and a hydraulic jump is form...

29th International Symposium on Shock Waves

CERN Document Server

Ranjan, Devesh

2015-01-01

This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion,  Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interes...

Numerical modelling of extreme waves by Smoothed Particle Hydrodynamics

Directory of Open Access Journals (Sweden)

M. H. Dao

2011-02-01

Full Text Available The impact of extreme/rogue waves can lead to serious damage of vessels as well as marine and coastal structures. Such extreme waves in deep water are characterized by steep wave fronts and an energetic wave crest. The process of wave breaking is highly complex and, apart from the general knowledge that impact loadings are highly impulsive, the dynamics of the breaking and impact are still poorly understood. Using an advanced numerical method, the Smoothed Particle Hydrodynamics enhanced with parallel computing is able to reproduce well the extreme waves and their breaking process. Once the waves and their breaking process are modelled successfully, the dynamics of the breaking and the characteristics of their impact on offshore structures could be studied. The computational methodology and numerical results are presented in this paper.

Internal wave structures in abyssal cataract flows

Science.gov (United States)

Makarenko, Nikolay; Liapidevskii, Valery; Morozov, Eugene; Tarakanov, Roman

2014-05-01

We discuss some theoretical approaches, experimental results and field data concerning wave phenomena in ocean near-bottom stratified flows. Such strong flows of cold water form everywhere in the Atlantic abyssal channels, and these currents play significant role in the global water exchange. Most interesting wave structures arise in a powerful cataract flows near orographic obstacles which disturb gravity currents by forced lee waves, attached hydraulic jumps, mixing layers etc. All these effects were observed by the authors in the Romanche and Chain fracture zones of Atlantic Ocean during recent cruises of the R/V Akademik Ioffe and R/V Akademik Sergei Vavilov (Morozov et al., Dokl. Earth Sci., 2012, 446(2)). In a general way, deep-water cataract flows down the slope are similar to the stratified flows examined in laboratory experiments. Strong mixing in the sill region leads to the splitting of the gravity current into the layers having the fluids with different densities. Another peculiarity is the presence of critical layers in shear flows sustained over the sill. In the case under consideration, this critical level separates the flow of near-bottom cold water from opposite overflow. In accordance with known theoretical models and laboratory measurements, the critical layer can absorb and reflect internal waves generated by the topography, so the upward propagation of these perturbations is blocked from above. High velocity gradients were registered downstream in the vicinity of cataract and it indicates the existence of developed wave structures beyond the sill formed by intense internal waves. This work was supported by RFBR (grants No 12-01-00671-a, 12-08-10001-k and 13-08-10001-k).

Interference of Locally Forced Internal Waves in Non-Uniform Stratifications

Science.gov (United States)

Supekar, Rohit; Peacock, Thomas

2017-11-01

Several studies have investigated the effect of constructive or destructive interference on the transmission of internal waves propagating through non-uniform stratifications. Such studies have been performed for internal waves that are spatiotemporally harmonic. To understand the effect of localization, we perform a theoretical and experimental study of the transmission of two-dimensional internal waves that are generated by a spatiotemporally localized boundary forcing. This is done by considering an idealized problem and applying a weakly viscous semi-analytic linear model. Parametric studies using this model show that localization leads to the disappearance of transmission peaks and troughs that would otherwise be present for a harmonic forcing. Laboratory experiments that we perform provide a clear indication of this physical effect. Based on the group velocity and angle of propagation of the internal waves, a practical criteria that assesses when the transmission peaks or troughs are evident, is obtained. It is found that there is a significant difference in the predicted energy transfer due to a harmonic and non-harmonic forcing which has direct implications to various physical forcings such as a storm over the ocean.

Numerical Simulation of Internal Waves in the Andaman Sea

Science.gov (United States)

Mohanty, Sachiko; Devendra Rao, Ambarukhana

2017-04-01

The interactions of barotropic tides with irregular bottom topography generate internal waves with high amplitude known as large-amplitude internal waves (LAIW) in the Andaman Sea. These waves are an important phenomena in the ocean due to their influence on the density structure and energy transfer into the region. These waves are also important in submarine acoustics, underwater navigation, offshore structures, ocean mixing, biogeochemical processes, etc. over the shelf-slope region. In the present study, energetics analysis of M2 internal tides over the Andaman Sea is carried out in detail by using a three-dimensional MIT general circulation ocean model (MITgcm). In-situ observations of temperature, conductivity and currents with high temporal resolution are used to validate the model simulations. From the spectral energy estimate of density, it is found that the peak estimate is associated with the semi-diurnal frequency at all the depths in both observations and model simulations. The baroclinic velocity characteristics, suggests that a multi-mode features of baroclinic tides are present at the buoy location. To understand the generation and propagation of internal tides over this region, energy flux and barotropic-to-baroclinic M2 tidal energy conversion rates are examined. The model simulation suggests that the internal tide is generated at multiple sites and propagate off of their respective generation sources. Most of the energy propagation in the Andaman Sea follows the 1000m isobath. The maximum horizontal kinetic energy follows the energy flux pattern over the domain and the available potential energy is found to be maximum in the north of the Andaman Sea.

Planetary wave-gravity wave interactions during mesospheric inversion layer events

Science.gov (United States)

Ramesh, K.; Sridharan, S.; Raghunath, K.; Vijaya Bhaskara Rao, S.; Bhavani Kumar, Y.

2013-07-01

lidar temperature observations over Gadanki (13.5°N, 79.2°E) show a few mesospheric inversion layer (MIL) events during 20-25 January 2007. The zonal mean removed SABER temperature shows warm anomalies around 50°E and 275°E indicating the presence of planetary wave of zonal wave number 2. The MIL amplitudes in SABER temperature averaged for 10°N-15°N and 70°E-90°E show a clear 2 day wave modulation during 20-28 January 2007. Prior to 20 January 2007, a strong 2day wave (zonal wave number 2) is observed in the height region of 80-90 km and it gets largely suppressed during 20-26 January 2007 as the condition for vertical propagation is not favorable, though it prevails at lower heights. The 10 day mean zonal wind over Tirunelveli (8.7°N, 77.8°E) shows deceleration of eastward winds indicating the westward drag due to wave dissipation. The nightly mean MF radar observed zonal winds show the presence of alternating eastward and westward winds during the period of 20-26 January 2007. The two dimensional spectrum of Rayleigh lidar temperature observations available for the nights of 20, 22, and 24 January 2007 shows the presence of gravity wave activity with periods 18 min, 38 min, 38 min, and vertical wavelengths 6.4 km, 4.0 km, 6.4 km respectively. From the dispersion relation of gravity waves, it is inferred that these waves are internal gravity waves rather than inertia gravity waves with the horizontal phase speeds of ~40 m/s, ~37 m/s, and ~50 m/s respectively. Assuming the gravity waves are eastward propagating waves, they get absorbed only in the eastward local wind fields of the planetary wave thereby causing turbulence and eddy diffusion which can be inferred from the estimation of large drag force due to the breaking of gravity wave leading to the formation of large amplitude inversion events in alternate nights. The present study shows that, the mesospheric temperature inversion is caused mainly due to the gravity wave breaking and the inversion

Importance of d-wave contributions in the charge symmetry breaking reaction dd →4Heπ0

Science.gov (United States)

Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Czerwiński, E.; Demmich, K.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K.; Fransson, K.; Goldenbaum, F.; Goswami, A.; Grigoryev, K.; Gullström, C.-O.; Hanhart, C.; Heijkenskjöld, L.; Hejny, V.; Hüsken, N.; Jarczyk, L.; Johansson, T.; Kamys, B.; Kemmerling, G.; Khatri, G.; Khoukaz, A.; Khreptak, O.; Kirillov, D. A.; Kistryn, S.; Kleines, H.; Kłos, B.; Krzemień, W.; Kulessa, P.; Kupść, A.; Kuzmin, A.; Lalwani, K.; Lersch, D.; Lorentz, B.; Magiera, A.; Maier, R.; Marciniewski, P.; Mariański, B.; Morsch, H.-P.; Moskal, P.; Ohm, H.; Parol, W.; Perez del Rio, E.; Piskunov, N. M.; Prasuhn, D.; Pszczel, D.; Pysz, K.; Pyszniak, A.; Ritman, J.; Roy, A.; Rudy, Z.; Rundel, O.; Sawant, S.; Schadmand, S.; Schätti-Ozerianska, I.; Sefzick, T.; Serdyuk, V.; Shwartz, B.; Sitterberg, K.; Skorodko, T.; Skurzok, M.; Smyrski, J.; Sopov, V.; Stassen, R.; Stepaniak, J.; Stephan, E.; Sterzenbach, G.; Stockhorst, H.; Ströher, H.; Szczurek, A.; Trzciński, A.; Wolke, M.; Wrońska, A.; Wüstner, P.; Yamamoto, A.; Zabierowski, J.; Zieliński, M. J.; Złomańczuk, J.; Żuprański, P.; Żurek, M.; WASA-at-COSY Collaboration

2018-06-01

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd →4Heπ0 using the WASA-at-COSY detector setup at an excess energy of Q = 60MeV. The determined differential cross section can be parametrized as d σ /d Ω = a + bcos2 ⁡θ*, where θ* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 ± 0.46(stat) + 0.32 - 0.8 (syst)) pb /sr and b = (13.1 ± 2.1 (stat)-2.7+1.0 (syst)) pb /sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd →4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.

International Standard Problems and Small Break Loss-of-Coolant Accident (SBLOCA

Directory of Open Access Journals (Sweden)

N. Aksan

2008-01-01

Full Text Available Best-estimate thermal-hydraulic system codes are widely used to perform safety and licensing analyses of nuclear power plants and also used in the design of advance reactors. Evaluation of the capabilities and the performance of these codes can be accomplished by comparing the code predictions with measured experimental data obtained on different test facilities. OECD/NEA Committee on the Safety of Nuclear Installations (CSNI has promoted, over the last twenty-nine years, some forty-eight international standard problems (ISPs. These ISPs were performed in different fields as in-vessel thermal-hydraulic behaviour, fuel behaviour under accident conditions, fission product release and transport, core/concrete interactions, hydrogen distribution and mixing, containment thermal-hydraulic behaviour. 80% of these ISPs were related to the working domain of principal working group no.2 on coolant system behaviour (PWG2 and were one of the major PWG2 activities for many years. A global review and synthesis on the contribution that ISPs have made to address nuclear reactor safety issues was initiated by CSNI-PWG2 and an overview on the subject of small break LOCA ISPs is given in this paper based on a report prepared by a writing group. In addition, the relevance of small break LOCA in a PWR with relation to nuclear reactor safety and the reorientation of the reactor safety program after TMI-2 accident are shortly summarized. The experiments in four integral test facilities, LOBI, SPES, BETHSY, ROSA IV/LSTF and the recorded data during a steam generator tube rupture transient in the DOEL-2 PWR (Belgium were the basis of the five small break LOCA related ISP exercises, which deal with the phenomenon typical of small break LOCAs in Western design PWRs. Some lessons learned from these small break LOCA ISPs are identified in relation to code deficiencies and capabilities, progress in the code capabilities, possibility of scaling, and various additional aspects

Self-organized Criticality Model for Ocean Internal Waves

International Nuclear Information System (INIS)

Wang Gang; Hou Yijun; Lin Min; Qiao Fangli

2009-01-01

In this paper, we present a simple spring-block model for ocean internal waves based on the self-organized criticality (SOC). The oscillations of the water blocks in the model display power-law behavior with an exponent of -2 in the frequency domain, which is similar to the current and sea water temperature spectra in the actual ocean and the universal Garrett and Munk deep ocean internal wave model [Geophysical Fluid Dynamics 2 (1972) 225; J. Geophys. Res. 80 (1975) 291]. The influence of the ratio of the driving force to the spring coefficient to SOC behaviors in the model is also discussed. (general)

Violent breaking wave impacts. Part 3. Effects of scale and aeration

DEFF Research Database (Denmark)

Bredmose, Henrik; Bullock, G. N.; Hogg, A. J.

2015-01-01

. The Bagnold-Mitsuyasu scaling law for the compression of an air pocket by a piston of incompressible water is rederived and generalised to 3D air pockets of arbitrary shape. Numerical results for wall pressure, force and impulse are then presented for a flip-through impact, a low-aeration impact and a high......The effects of scale and aeration on violent breaking wave impacts with trapped and entrained air are investigated both analytically and numerically. By dimensional analysis we show that the impact pressures for Froude scaled conditions prior to the impact depend on the scale and aeration level......-aeration impact, for nine scales and five levels of initial aeration. Two of these impact types trap a pocket of air at the wall. Among the findings of the paper is that for fixed initial aeration, impact pressures from the flip-through impact broadly follow Froude scaling. This is also the case for the two...

Numerical assessment of factors affecting nonlinear internal waves in the South China Sea

Science.gov (United States)

Li, Qiang

2014-02-01

Nonlinear internal waves in the South China Sea exhibit diverse characteristics, which are associated with the complex conditions in Luzon Strait, such as the double ridge topography, the Earth’s rotation, variations in stratification and the background current induced by the Kuroshio. These effects are individually assessed using the MITgcm. The performance of the model is first validated through comparison with field observations. Because of in-phased ray interaction, the western ridge in Luzon Strait intensifies the semidiurnal internal tides generated from the eastern ridge, thus reinforcing the formation of nonlinear internal waves. However, the ray interaction for K1 forcing becomes anti-phased so that the K1 internal tide generation is reduced by the western ridge. Not only does the rotational dispersion suppress internal tide generation, it also inhibits nonlinear steepening and consequent internal solitary wave formation. As a joint effect, the double ridges and the rotational dispersion result in a paradoxical phenomenon: diurnal barotropic tidal forcing is dominant in Luzon Strait, but semidiurnal internal tides prevail in the deep basin of the South China Sea. The seasonal variation of the Kuroshio is consistent with the seasonal appearance of nonlinear internal waves in the South China Sea. The model results show that the westward inflow due to the Kuroshio intrusion reduces the amplitude of internal tides in the South China Sea, causing the weakening or absence of internal solitary waves. Winter stratification cannot account for the significant reduction of nonlinear internal waves, because the amplitude growth of internal tides due to increased thermocline tilting counteracts the reduced nonlinearity caused by thermocline deepening.

Intermittent large amplitude internal waves observed in Port Susan, Puget Sound

Science.gov (United States)

Harris, J. C.; Decker, L.

2017-07-01

A previously unreported internal tidal bore, which evolves into solitary internal wave packets, was observed in Port Susan, Puget Sound, and the timing, speed, and amplitude of the waves were measured by CTD and visual observation. Acoustic Doppler current profiler (ADCP) measurements were attempted, but unsuccessful. The waves appear to be generated with the ebb flow along the tidal flats of the Stillaguamish River, and the speed and width of the resulting waves can be predicted from second-order KdV theory. Their eventual dissipation may contribute significantly to surface mixing locally, particularly in comparison with the local dissipation due to the tides. Visually the waves appear in fair weather as a strong foam front, which is less visible the farther they propagate.

Multi-scale phenomena of rotation-modified mode-2 internal waves

Science.gov (United States)

Deepwell, David; Stastna, Marek; Coutino, Aaron

2018-03-01

We present high-resolution, three-dimensional simulations of rotation-modified mode-2 internal solitary waves at various rotation rates and Schmidt numbers. Rotation is seen to change the internal solitary-like waves observed in the absence of rotation into a leading Kelvin wave followed by Poincaré waves. Mass and energy is found to be advected towards the right-most side wall (for a Northern Hemisphere rotation), leading to increased amplitude of the leading Kelvin wave and the formation of Kelvin-Helmholtz (K-H) instabilities on the upper and lower edges of the deformed pycnocline. These fundamentally three-dimensional instabilities are localized within a region near the side wall and intensify in vigour with increasing rotation rate. Secondary Kelvin waves form further behind the wave from either resonance with radiating Poincaré waves or the remnants of the K-H instability. The first of these mechanisms is in accord with published work on mode-1 Kelvin waves; the second is, to the best of our knowledge, novel to the present study. Both types of secondary Kelvin waves form on the same side of the channel as the leading Kelvin wave. Comparisons of equivalent cases with different Schmidt numbers indicate that while adopting a numerically advantageous low Schmidt number results in the correct general characteristics of the Kelvin waves, excessive diffusion of the pycnocline and various density features precludes accurate representation of both the trailing Poincaré wave field and the intensity and duration of the Kelvin-Helmholtz instabilities.

Waves in the seas

Digital Repository Service at National Institute of Oceanography (India)

Varkey, M.J

, steep nonsymmetric cnoidal waves, solitons and random waves. They have different properties too. Any wave form has a wave period (T), wave height (H) and speed (C) which depends on T. Still another type of waves are breaking waves near a coast...

International Shock-Wave Database: Current Status

Science.gov (United States)

Levashov, Pavel

2013-06-01

Shock-wave and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Since the middle of the 20th century vast amount of shock-wave experimental information has been obtained. To systemize it a number of compendiums of shock-wave data has been issued by LLNL, LANL (USA), CEA (France), IPCP and VNIIEF (Russia). In mid-90th the drawbacks of the paper handbooks became obvious, so the first version of the online shock-wave database appeared in 1997 (http://www.ficp.ac.ru/rusbank). It includes approximately 20000 experimental points on shock compression, adiabatic expansion, measurements of sound velocity behind the shock front and free-surface-velocity for more than 650 substances. This is still a useful tool for the shock-wave community, but it has a number of serious disadvantages which can't be easily eliminated: (i) very simple data format for points and references; (ii) minimalistic user interface for data addition; (iii) absence of history of changes; (iv) bad feedback from users. The new International Shock-Wave database (ISWdb) is intended to solve these and some other problems. The ISWdb project objectives are: (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of shock-wave and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models; and (ii) to make this database available internationally through the Internet, in an interactive form. The development and operation of the ISWdb is guided by an advisory committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA (currently only one server is available). The database provides access to original experimental data on shock compression, non-shock dynamic loadings, isentropic expansion, measurements of sound

Analysis of the Scattering Characteristics of Sea Surface with the Influence from Internal Wave

Directory of Open Access Journals (Sweden)

Wei Yi-wen

2015-06-01

Full Text Available The internal wave travels beneath the sea surface and modulate the roughness of the sea surface through the wave-current interaction. This makes some dark and bright bands can be observed in the Synthetic Aperture Radar (SAR images. In this paper, we first establish the profile of the internal wave based on the KdV equations; then, the action balance equation and the wave-current interaction source function are used to modify the sea spectrum; finally, the two-scale theory based facet model is combined with the modified sea spectrum to calculate the scattering characteristics of the sea. We have simulated the scattering coefficient distribution of the sea with an internal wave traveling through. The influence on the scattering coefficients and the Doppler spectra under different internal wave parameters and sea state parameters are analyzed.

Parametric instability and wave turbulence driven by tidal excitation of internal waves

Science.gov (United States)

Le Reun, Thomas; Favier, Benjamin; Le Bars, Michael

2018-04-01

We investigate the stability of stratified fluid layers undergoing homogeneous and periodic tidal deformation. We first introduce a local model which allows to study velocity and buoyancy fluctuations in a Lagrangian domain periodically stretched and sheared by the tidal base flow. While keeping the key physical ingredients only, such a model is efficient to simulate planetary regimes where tidal amplitudes and dissipation are small. With this model, we prove that tidal flows are able to drive parametric subharmonic resonances of internal waves, in a way reminiscent of the elliptical instability in rotating fluids. The growth rates computed via Direct Numerical Simulations (DNS) are in very good agreement with WKB analysis and Floquet theory. We also investigate the turbulence driven by this instability mechanism. With spatio-temporal analysis, we show that it is a weak internal wave turbulence occurring at small Froude and buoyancy Reynolds numbers. When the gap between the excitation and the Brunt-V\\"ais\\"al\\"a frequencies is increased, the frequency spectrum of this wave turbulence displays a -2 power law reminiscent of the high-frequency branch of the Garett and Munk spectrum (Garrett & Munk 1979) which has been measured in the oceans. In addition, we find that the mixing efficiency is altered compared to what is computed in the context of DNS of stratified turbulence excited at small Froude and large buoyancy Reynolds numbers and is consistent with a superposition of waves.

Internal wave attractors: different scenarios of instability

OpenAIRE

Brouzet, Christophe; Ermanyuk, E. V.; Joubaud, Sylvain; Pillet, Grimaud; Dauxois, Thierry

2017-01-01

International audience; This paper presents an experimental study of different instability scenarios in a parallelogram-shaped internal wave attractor in a trapezoidal domain filled with a uniformly stratified fluid.Energy is injected into the system via the oscillatory motion of a vertical wall of the trapezoidal domain. Whole-field velocity measurements are performed with the conventional PIV technique. In the linear regime, the total kinetic energyof the fluid system is used to quantify th...

The viscous lee wave problem and its implications for ocean modelling

Science.gov (United States)

Shakespeare, Callum J.; Hogg, Andrew McC.

2017-05-01

Ocean circulation models employ 'turbulent' viscosity and diffusivity to represent unresolved sub-gridscale processes such as breaking internal waves. Computational power has now advanced sufficiently to permit regional ocean circulation models to be run at sufficiently high (100 m-1 km) horizontal resolution to resolve a significant part of the internal wave spectrum. Here we develop theory for boundary generated internal waves in such models, and in particular, where the waves dissipate their energy. We focus specifically on the steady lee wave problem where stationary waves are generated by a large-scale flow acting across ocean bottom topography. We generalise the energy flux expressions of [Bell, T., 1975. Topographically generated internal waves in the open ocean. J. Geophys. Res. 80, 320-327] to include the effect of arbitrary viscosity and diffusivity. Applying these results for realistic parameter choices we show that in the present generation of models with O(1) m2s-1 horizontal viscosity/diffusivity boundary-generated waves will inevitably dissipate the majority of their energy within a few hundred metres of the boundary. This dissipation is a direct consequence of the artificially high viscosity/diffusivity, which is not always physically justified in numerical models. Hence, caution is necessary in comparing model results to ocean observations. Our theory further predicts that O(10-2) m2s-1 horizontal and O(10-4) m2s-1 vertical viscosity/diffusivity is required to achieve a qualitatively inviscid representation of internal wave dynamics in ocean models.

A Note on Standing Internal Inertial Gravity Waves of Finite Amplitude

Science.gov (United States)

Thorpe, S. A.

2003-01-01

The effects of finite amplitude are examined in two-dimensional, standing, internal gravity waves in a rectangular container which rotates about a vertical axis at frequency f/2. Expressions are given for the velocity components, density fluctuations and isopycnal displacements to second order in the wave steepness in fluids with buoyancy frequency, N, of general form, and the effect of finite amplitude on wave frequency is given in an expansion to third order. The first order solutions, and the solutions to second order in the absence of rotation, are shown to conserve energy during a wave cycle. Analytical solutions are found to second order for the first two modes in a deep fluid with N proportional to sech(az), where z is the upward vertical coordinate and a is scaling factor. In the absence of rotation, results for the first mode in the latter stratification are found to be consistent with those for interfacial waves. An analytical solution to fourth order in a fluid with constant N is given and used to examine the effects of rotation on the development of static instability or of conditions in which shear instability may occur. As in progressive internal waves, an effect of rotation is to enhance the possibility of shear instability for waves with frequencies close to f. The analysis points to a significant difference between the dynamics of standing waves in containers of limited size and progressive internal waves in an unlimited fluid; the effect of boundaries on standing waves may inhibit the onset of instability. A possible application of the analysis is to transverse oscillations in long, narrow, steep-sided lakes such as Loch Ness, Scotland.

Virtual Seafloor Reduces Internal Wave Generation by Tidal Flow

Science.gov (United States)

Zhang, Likun; Swinney, Harry L.

2014-03-01

Our numerical simulations of tidal flow of a stratified fluid over periodic knife-edge ridges and random topography reveal that the time-averaged tidal energy converted into internal gravity wave radiation arises only from the section of a ridge above a virtual seafloor. The average radiated power is approximated by the power predicted by linear theory if the height of the ridge is measured relative to the virtual floor. The concept of a virtual floor can extend the applicability of linear theory to global predictions of the conversion of tidal energy into internal wave energy in the oceans.

A non-intrusive and continuous-in-space technique to investigate the wave transformation and breaking over a breakwater

Directory of Open Access Journals (Sweden)

Ferrari Simone

2016-01-01

Full Text Available To design longshore breakwaters, the evaluation of the wave motion transformations over the structures and of the energy they are able to absorb, dissipate and reflect is necessary. To characterize features and transformations of monochromatic wave trains above a breakwater, both submerged and emerged, we have designed and developed a non-intrusive and continuous-in-space technique, based on Image Analysis, and carried out an experimental campaign, in a laboratory flume equipped with a wave-maker, in order to test it. The investigation area was lighted with a light sheet and images were recorded by a video-camera. The working fluid was seeded with non buoyant particles to make it bright and clearly distinct from dark background and breakwater. The technique, that is based on a robust algorithm to identify the free surface, has showed to properly work also in prohibitive situations for traditional resistive probes (e.g., very shallow waters and/or breaking waves and to be able to measure the free surface all over the investigation field in a non-intrusive way. Two kind of analysis were mainly performed, a statistical and a spectral one. The peculiarities of the measurement technique allowed to describe the whole wave transformation and to supply useful information for design purposes.

Kinematic parameters of internal waves of the second mode in the South China Sea

Directory of Open Access Journals (Sweden)

O. Kurkina

2017-10-01

Full Text Available Spatial distributions of the main properties of the mode function and kinematic and non-linear parameters of internal waves of the second mode are derived for the South China Sea for typical summer conditions in July. The calculations are based on the Generalized Digital Environmental Model (GDEM climatology of hydrological variables, from which the local stratification is evaluated. The focus is on the phase speed of long internal waves and the coefficients at the dispersive, quadratic and cubic terms of the weakly non-linear Gardner model. Spatial distributions of these parameters, except for the coefficient at the cubic term, are qualitatively similar for waves of both modes. The dispersive term of Gardner's equation and phase speed for internal waves of the second mode are about a quarter and half, respectively, of those for waves of the first mode. Similarly to the waves of the first mode, the coefficients at the quadratic and cubic terms of Gardner's equation are practically independent of water depth. In contrast to the waves of the first mode, for waves of the second mode the quadratic term is mostly negative. The results can serve as a basis for expressing estimates of the expected parameters of internal waves for the South China Sea.

Turbulence beneath finite amplitude water waves

Energy Technology Data Exchange (ETDEWEB)

Beya, J.F. [Universidad de Valparaiso, Escuela de Ingenieria Civil Oceanica, Facultad de Ingenieria, Valparaiso (Chile); The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Peirson, W.L. [The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Banner, M.L. [The University of New South Wales, School of Mathematics and Statistics, Sydney, NSW (Australia)

2012-05-15

Babanin and Haus (J Phys Oceanogr 39:2675-2679, 2009) recently presented evidence of near-surface turbulence generated below steep non-breaking deep-water waves. They proposed a threshold wave parameter a {sup 2}{omega}/{nu} = 3,000 for the spontaneous occurrence of turbulence beneath surface waves. This is in contrast to conventional understanding that irrotational wave theories provide a good approximation of non-wind-forced wave behaviour as validated by classical experiments. Many laboratory wave experiments were carried out in the early 1960s (e.g. Wiegel 1964). In those experiments, no evidence of turbulence was reported, and steep waves behaved as predicted by the high-order irrotational wave theories within the accuracy of the theories and experimental techniques at the time. This contribution describes flow visualisation experiments for steep non-breaking waves using conventional dye techniques in the wave boundary layer extending above the wave trough level. The measurements showed no evidence of turbulent mixing up to a value of a {sup 2}{omega}/{nu} = 7,000 at which breaking commenced in these experiments. These present findings are in accord with the conventional understandings of wave behaviour. (orig.)

Symmetry breaking in small rotating clouds of trapped ultracold Bose atoms

International Nuclear Information System (INIS)

Dagnino, D.; Barberan, N.; Riera, A.; Osterloh, K.; Lewenstein, M.

2007-01-01

We study the signatures of rotational and phase symmetry breaking in small rotating clouds of trapped ultracold Bose atoms by looking at rigorously defined condensate wave function. Rotational symmetry breaking occurs in narrow frequency windows, where energy degeneracy between the lowest energy states of different total angular momentum takes place. This leads to a complex condensate wave function that exhibits vortices clearly seen as holes in the density, as well as characteristic local phase patterns, reflecting the appearance of vorticities. Phase symmetry (or gauge symmetry) breaking, on the other hand, is clearly manifested in the interference of two independent rotating clouds

Internal solitary waves on the Saya de Malha bank of the Mascarene Plateau: SAR observations and interpretation

Science.gov (United States)

New, A. L.; Magalhaes, J. M.; da Silva, J. C. B.

2013-09-01

Energetic Internal Solitary Waves (ISWs) were recently discovered radiating from the central region of the Mascarene Plateau in the south-western Indian Ocean (da Silva et al., 2011). SAR imagery revealed the two-dimensional structure of the waves which propagated for several hundred kilometres in deep water both to the east and west of a sill, located near 12.5°S, 61°E between the Saya de Malha and Nazareth banks. These waves were presumed to originate from the disintegration of a large lee wave formed on the western side of the sill at the time of maximum barotropic flow to the west. In the present paper we focus instead on ISWs propagating in the shallow water above the Saya da Malha (SM) bank (to the north of the sill), rather than on those propagating in deep water (here denominated as type-I or -II waves if propagating to the west or east respectively). Analysis of an extended SAR image dataset reveals strong sea surface signatures of complex patterns of ISWs propagating over the SM bank arising from different sources. We identify three distinct types of waves, and propose suitable generation mechanisms for them using synergy from different remotely sensed datasets, together with analyses of linear phase speeds (resulting from local stratification and bathymetry). In particular, we find a family of ISWs (termed here A-type waves) which results from the disintegration of a lee wave which forms on the western slopes of SM. We also identify two further wave trains (B- and C-type waves) which we suggest result from refraction of the deep water type-I and -II waves onto the SM bank. Therefore, both B- and C-type waves can be considered to result from the same generation source as the type-I and -II waves. Finally, we consider the implications of the ISWs for mixing and biological production over the SM bank, and provide direct evidence, from ocean colour satellite images, of enhanced surface chlorophyll over a shallow topographic feature on the bank, which is

Inclusive measurements of the break-up of 156 MeV 6Li-ions at extreme forward angles and the quasi free break-up model

International Nuclear Information System (INIS)

Jellito, H.; Buschmann, J.; Gils, H.J.; Heide, N.; Kiener, J.; Rebel, H.; Zagromski, S.; Samanta, C.

1988-11-01

Inclusive alpha particle and deuteron spectra from collisions of 156 MeV 6 Li-ions with 12 C and 208 Pb were measured at extreme forward emission angles including zero degree. The measurements were performed with the Karlsruhe magnetic spectrograph 'Little John' and required an efficient reduction of the background from small-angle scattering. The observed double differential cross sections and angular distributions have been analysed on the basis of Serber's spectator break-up model. When going to angles smaller than grazing, where Coulomb effects are expected to the dominating, transitional features may appear. Corresponding effects probably associated with Coulomb break-up are observed with the 208 Pb-target and require a slight extension of the Serber approach. In the case of the 12 C-target the break-up cross sections in forward direction seem to reflect the shape of the internal momentum distribution of the alpha particle and deuteron cluster in the 6 Li-projectile and are in agreement with a 2S-type wave function. However, at larger angles the shape appears to be distorted, possibly by final state interactions. (orig.) [de

Internal energy relaxation in shock wave structure

International Nuclear Information System (INIS)

Josyula, Eswar; Suchyta, Casimir J.; Boyd, Iain D.; Vedula, Prakash

2013-01-01

The Wang Chang-Uhlenbeck (WCU) equation is numerically integrated to characterize the internal structure of Mach 3 and Mach 5 shock waves in a gas with excitation in the internal energy states for the treatment of inelastic collisions. Elastic collisions are modeled with the hard sphere collision model and the transition rates for the inelastic collisions modified appropriately using probabilities based on relative velocities of the colliding particles. The collision integral is evaluated by the conservative discrete ordinate method [F. Tcheremissine, “Solution of the Boltzmann kinetic equation for high-speed flows,” Comput. Math. Math. Phys. 46, 315–329 (2006); F. Cheremisin, “Solution of the Wang Chang-Uhlenbeck equation,” Dokl. Phys. 47, 487–490 (2002)] developed for the Boltzmann equation. For the treatment of the diatomic molecules, the internal energy modes in the Boltzmann equation are described quantum mechanically given by the WCU equation. As a first step in the treatment of the inelastic collisions by the WCU equation, a two- and three-quantum system is considered to study the effect of the varying of (1) the inelastic cross section and (2) the energy gap between the quantum energy states. An alternative method, the direct simulation Monte Carlo method, is used for the Mach 3 shock wave to ensure the consistency of implementation in the two methods and there is an excellent agreement between the two methods. The results from the WCU implementation showed consistent trends for the Mach 3 and Mach5 standing shock waves simulations. Inelastic contributions change the downstream equilibrium state and allow the flow to transition to the equilibrium state further upstream

Impacts of wave-induced circulation in the surf zone on wave setup

Science.gov (United States)

Guérin, Thomas; Bertin, Xavier; Coulombier, Thibault; de Bakker, Anouk

2018-03-01

Wave setup corresponds to the increase in mean water level along the coast associated with the breaking of short-waves and is of key importance for coastal dynamics, as it contributes to storm surges and the generation of undertows. Although overall well explained by the divergence of the momentum flux associated with short waves in the surf zone, several studies reported substantial underestimations along the coastline. This paper investigates the impacts of the wave-induced circulation that takes place in the surf zone on wave setup, based on the analysis of 3D modelling results. A 3D phase-averaged modelling system using a vortex force formalism is applied to hindcast an unpublished field experiment, carried out at a dissipative beach under moderate to very energetic wave conditions (Hm 0 = 6m at breaking and Tp = 22s). When using an adaptive wave breaking parameterisation based on the beach slope, model predictions for water levels, short waves and undertows improved by about 30%, with errors reducing to 0.10 m, 0.10 m and 0.09 m/s, respectively. The analysis of model results suggests a very limited impact of the vertical circulation on wave setup at this dissipative beach. When extending this analysis to idealized simulations for different beach slopes ranging from 0.01 to 0.05, it shows that the contribution of the vertical circulation (horizontal and vertical advection and vertical viscosity terms) becomes more and more relevant as the beach slope increases. In contrast, for a given beach slope, the wave height at the breaking point has a limited impact on the relative contribution of the vertical circulation on the wave setup. For a slope of 0.05, the contribution of the terms associated with the vertical circulation accounts for up to 17% (i.e. a 20% increase) of the total setup at the shoreline, which provides a new explanation for the underestimations reported in previously published studies.

Calculation of BETHSY 0.5% small break LOCA with RELAP5-ISP 27 international activity of code assessment

International Nuclear Information System (INIS)

Chen Yuzhen

1992-01-01

BETHSY facility constructed in France is a 1/100 volumetrically-scaled full-pressure model of a PWR with 3 loops. ISP-27 is an international activity sponsored by OECD Nuclear Energy Agency. The experiment is a transient of 0.5% coldleg break LOCA with failure of HPIS. The calculations were performed with RELAP5/MOD2/36.05 at CYBER-170/825, which can present a good calculation, provided that the break flow is well modelled

Solar Internal Rotation and Dynamo Waves: A Two Dimensional ...

Indian Academy of Sciences (India)

tribpo

Solar Internal Rotation and Dynamo Waves: A Two Dimensional. Asymptotic Solution in the Convection Zone ... We calculate here a spatial 2 D structure of the mean magnetic field, adopting real profiles of the solar internal ... of the asymptotic solution in low (middle) and high (right panel) latitudes. field is shifted towards the ...

Breaking wave impact on offshore tripod structures. Comparison of large scale experiments, CFD simulations, and DIN recommended practice; Wellenbrechen an Offshore Tripod-Gruendungen. Versuche und Simulationen im Vergleich zu Richtlinien

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Arndt; Schlurmann, Torsten [Hannover Univ. (Germany). Franzius-Institut fuer Wasserbau und Kuesteningenieurwesen

2012-05-15

Coastal and near shore areas offer a large potential for offshore wind energy production due to strong and steady wind conditions. Thousands of offshore wind energy converters are projected for mass production within the next years. Detailed understanding of the extreme, dynamic wave loads on offshore structures is essential for an efficient design. The impact on structures is a complex process and further studies are required for more detailed load assessments, which is why breaking wave loads were investigated by the research project ''GIGAWIND alpha ventus - Subproject 1'' within the network ''Research at Alpha VEntus'' (RAVE). Large scale laboratory tests (1:12) with breaking waves have been carried out at the Large Wave Flume of the ''Forschungszentrum Kueste'' (FZK, Hanover) to reveal more detailed insights on the impact area, duration and development of the wave induced momentum, and intensity of pressures. In addition, local pressures calculated by a three-dimensional numerical impact simulation are compared to the Large Wave Flume experiments. Slamming coefficients have been derived from the physical model tests and CFD simulations for the comparison to load calculations based on guidelines. (orig.)

The instability of internal gravity waves to localised disturbances

Directory of Open Access Journals (Sweden)

J. Vanneste

1995-02-01

Full Text Available The instability of an internal gravity wave due to nonlinear wave-wave interaction is studied theoretically and numerically. Three different aspects of this phenomenon are examined. 1. The influence of dissipation on both the resonant and the nonresonant interactions is analysed using a normal mode expansion of the basic equations. In particular, the modifications induced in the interaction domain are calculated and as a result some modes are shown to be destabilised by dissipation. 2. The evolution of an initial unstable disturbance of finite vertical extent is described as the growth of two secondary wave packets travelling at the same group velocity. A quasi-linear correction to the basic primary wave is calculated, corresponding to a localised amplitude decrease due to the disturbance growth. 3. Numerical experiments are carried out to study the effect of a basic shear on wave instability. It appears that the growing secondary waves can have a frequency larger than that of the primary wave, provided that the shear is sufficient. The instability of waves with large amplitude and long period, such as tides or planetary waves, could therefore be invoked as a possible mechanism for the generation of gravity waves with shorter period in the middle atmosphere.

Experimental study of the formation of steep waves and breakers

Directory of Open Access Journals (Sweden)

Stanis³aw R. Massel

2001-09-01

Full Text Available Breaking waves (whitecaps are one of the most important and least understood processes associated with the evolution of the surface gravity wave field in the open sea. This process is the principal means by which energy and momentum are transferred away from a developing sea. However, an estimation of the frequency of breaking waves or the fraction of sea surface covered by whitecaps and the amount of dissipated energy induced by breaking is very difficult to carry out under real sea conditions. A controlled experiment, funded by the European Commission under the Improving Human Potential Access Infrastructures programme, was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway. Simulation of random waves of the prescribed spectra by wave makers provided a very realistic pattern of the sea surface. The number of breaking waves was estimated by photographing the sea surface and recording the noise caused by the breaking waves. The experimental data will serve for calibration of the theoretical models of the sea surface fraction related to the whitecaps.

Experimental observation of strong mixing due to internal wave focusing over sloping terrain

NARCIS (Netherlands)

Swart, A.; Manders, A.; Harlander, U.; Maas, L.R.M.

2010-01-01

This paper reports on experimental observation of internal waves that are focused due to a sloping topography. A remarkable mixing of the density field was observed. This result is of importance for the deep ocean, where internal waves are believed to play a role in mixing. The experiments were

Verification of model wave heights with long-term moored buoy data: Application to wave field over the Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Samiksha, S.V.; Polnikov, V.G.; Vethamony, P.; Rashmi, R.; Pogarskii, F.; Sudheesh, K.

. Res. 106(C6), 11659-11676 Babanin, A.V., 2011. Breaking and Dissipation of Ocean Surface Waves. Book, Cambridge University Press, 480p Banner, M. L., Gemmrich, J. R., and Farmer, D. M., 2002. Multiscale measurements of ocean wave breaking...

Non-dispersive traveling waves in inclined shallow water channels

International Nuclear Information System (INIS)

Didenkulova, Ira; Pelinovsky, Efim

2009-01-01

Existence of traveling waves propagating without internal reflection in inclined water channels of arbitrary slope is demonstrated. It is shown that traveling non-monochromatic waves exist in both linear and nonlinear shallow water theories in the case of a uniformly inclined channel with a parabolic cross-section. The properties of these waves are studied. It is shown that linear traveling waves should have a sign-variable shape. The amplitude of linear traveling waves in a channel satisfies the same Green's law, which is usually derived from the energy flux conservation for smoothly inhomogeneous media. Amplitudes of nonlinear traveling waves deviate from the linear Green's law, and the behavior of positive and negative amplitudes are different. Negative amplitude grows faster than positive amplitude in shallow water. The phase of nonlinear waves (travel time) is described well by the linear WKB approach. It is shown that nonlinear traveling waves of any amplitude always break near the shoreline if the boundary condition of the full absorption is applied.

An Asymptotic and Stochastic Theory for the Effects of Surface Gravity Waves on Currents and Infragravity Waves

Science.gov (United States)

McWilliams, J. C.; Lane, E.; Melville, K.; Restrepo, J.; Sullivan, P.

2004-12-01

Oceanic surface gravity waves are approximately irrotational, weakly nonlinear, and conservative, and they have a much shorter time scale than oceanic currents and longer waves (e.g., infragravity waves) --- except where the primary surface waves break. This provides a framework for an asymptotic theory, based on separation of time (and space) scales, of wave-averaged effects associated with the conservative primary wave dynamics combined with a stochastic representation of the momentum transfer and induced mixing associated with non-conservative wave breaking. Such a theory requires only modest information about the primary wave field from measurements or operational model forecasts and thus avoids the enormous burden of calculating the waves on their intrinsically small space and time scales. For the conservative effects, the result is a vortex force associated with the primary wave's Stokes drift; a wave-averaged Bernoulli head and sea-level set-up; and an incremental material advection by the Stokes drift. This can be compared to the "radiation stress" formalism of Longuet-Higgins, Stewart, and Hasselmann; it is shown to be a preferable representation since the radiation stress is trivial at its apparent leading order. For the non-conservative breaking effects, a population of stochastic impulses is added to the current and infragravity momentum equations with distribution functions taken from measurements. In offshore wind-wave equilibria, these impulses replace the conventional surface wind stress and cause significant differences in the surface boundary layer currents and entrainment rate, particularly when acting in combination with the conservative vortex force. In the surf zone, where breaking associated with shoaling removes nearly all of the primary wave momentum and energy, the stochastic forcing plays an analogous role as the widely used nearshore radiation stress parameterizations. This talk describes the theoretical framework and presents some

Near-surface current meter array measurements of internal gravity waves

Energy Technology Data Exchange (ETDEWEB)

Jones, H.B.E. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

We have developed various processing algorithms used to estimate the wave forms produced by hydrodynamic Internal Waves. Furthermore, the estimated Internal Waves are used to calculate the Modulation Transfer Function (MTF) which relates the current and strain rate subsurface fields to surface scattering phenomenon imaged by radar. Following a brief discussion of LLNL`s measurement platform (a 10 sensor current meter array) we described the generation of representative current and strain rate space-time images from measured or simulated data. Then, we present how our simulation capability highlighted limitations in estimating strain rate. These limitations spurred the application of beamforming techniques to enhance our estimates, albeit at the expense of collapsing our space-time images to 1-D estimates. Finally, we discuss progress with regard to processing the current meter array data captured during the recent Loch Linnhe field trials.

Experimental determination of radiated internal wave power without pressure field data

OpenAIRE

Lee, Frank M.; Paoletti, M. S.; Swinney, Harry L.; Morrison, P. J.

2014-01-01

We present a method to determine, using only velocity field data, the time-averaged energy flux $\\left$ and total radiated power $P$ for two-dimensional internal gravity waves. Both $\\left$ and $P$ are determined from expressions involving only a scalar function, the stream function $\\psi$. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method...

Analysis OpenMP performance of AMD and Intel architecture for breaking waves simulation using MPS

Science.gov (United States)

Alamsyah, M. N. A.; Utomo, A.; Gunawan, P. H.

2018-03-01

Simulation of breaking waves by using Navier-Stokes equation via moving particle semi-implicit method (MPS) over close domain is given. The results show the parallel computing on multicore architecture using OpenMP platform can reduce the computational time almost half of the serial time. Here, the comparison using two computer architectures (AMD and Intel) are performed. The results using Intel architecture is shown better than AMD architecture in CPU time. However, in efficiency, the computer with AMD architecture gives slightly higher than the Intel. For the simulation by 1512 number of particles, the CPU time using Intel and AMD are 12662.47 and 28282.30 respectively. Moreover, the efficiency using similar number of particles, AMD obtains 50.09 % and Intel up to 49.42 %.

Preliminary study of internal wave effects to chlorophyll distribution in the Lombok Strait and adjacent areas

Science.gov (United States)

Arvelyna, Yessy; Oshima, Masaki

2005-01-01

This paper studies the effect of internal wave in the Lombok Strait to chlorophyll distribution in the surrounded areas using ERS SAR, ASTER, SeaWiFS and AVHRR-NOAA images data during 1996-2004 periods. The observation results shows that the internal waves were propagated to the south and the north of strait and mostly occurred during transitional season from dry to wet and wet season (rainy season) between September to December when the layers are strongly stratified. Wavelet transform of image using Meyer wavelet analysis is applied for internal wave detection in ERS SAR and ASTER images, for symmetric extension of data at the image boundaries, to prevent discontinuities by a periodic wrapping of data in fast algorithm and space-saving code. Internal wave created elongated pattern in detail and approximation of image from level 2 to 5 and retained value between 2-4.59 times compared to sea surface, provided accuracy in classification over than 80%. In segmentation process, the Canny edge detector is applied on the approximation image at level two to derive internal wave signature in image. The proposed method can extract the internal wave signature, maintain the continuity of crest line while reduce small strikes from noise. The segmentation result, i.e. the length between crest and trough, is used to compute the internal wave induced current using Korteweg-de Vries (KdV) equation. On ERS SAR data contains surface signature of internal wave (2001/8/20), we calculated that internal wave propagation speed was 1.2 m/s and internal wave induced current was 0.56 m/s, respectively. From the observation of ERS SAR and SeaWiFS images data, we found out that the distribution of maximum chlorophyll area at southern coastline off Bali Island when strong internal wave induced current occurred in south of the Lombok Strait was distributed further to westward, i.e. from 9.25°-10.25°LS, 115°-116.25°SE to 8.8°-10.7°LS, 114.5°-116°SE, and surface chlorophyll concentration

Horizontal Coherence of Wave Forces on Vertical Wall Breakwaters

DEFF Research Database (Denmark)

Archetti, Renata; Lamberti, Alberto; Martinelli, Luca

2001-01-01

Evaluation of spatial coherence of breaking waves is of great importance and of recent interest.......Evaluation of spatial coherence of breaking waves is of great importance and of recent interest....

Advection of pollutants by internal solitary waves in oceanic and atmospheric stable stratifications

Directory of Open Access Journals (Sweden)

G. W. Haarlemmer

1998-01-01

Full Text Available When a pollutant is released into the ocean or atmosphere under turbulent conditions, even a steady release is captured by large eddies resulting in localized patches of high concentration of the pollutant. If such a cloud of pollutant subsequently enters a stable stratification-either a pycnocline or thermocline-then internal waves are excited. Since large solitary internal waves have a recirculating core, pollutants may be trapped in the sclitary wave, and advected large distances through the waveguide provided by the stratification. This paper addresses the mechanisms, through computer and physical simulation, by which a localized release of a dense pollutant results in solitary waves that trap the pollutant or disperse the pollutant faster than in the absence of the waves.

Energy Release Through Internal Wave Breaking

NARCIS (Netherlands)

van Haren, H.; Gostiaux, L.

2012-01-01

The sun inputs huge amounts of heat to the ocean, heat that would stay near the ocean's surface if it were not mechanically mixed into the deep. Warm water is less dense than cold water, so that heated surface waters "float" on top of the cold deep waters. Only active mechanical turbulent mixing can

On Internal Waves in a Density-Stratified Estuary

NARCIS (Netherlands)

Kranenburg, C.

1991-01-01

In this article some field observations, made in recent years, of internal wave motions in a density-stratified estuary are presented, In order to facilitate the appreciation of the results, and to make some quantitative comparisons, the relevant theory is also summarized. Furthermore, the origins

Making waves: visualizing fluid flows

NARCIS (Netherlands)

Zweers, Wout; Zwart, Valerie; Bokhove, Onno

2013-01-01

We explore the visualization of violent wave dynamics and erosion by waves and jets in laser-cut reliefs, laser engravings, and three-dimensional printing. For this purpose we built table-top experiments to cast breaking waves, and also explored the creation of extreme or rogue waves in larger wave

Acoustic mode coupling induced by shallow water nonlinear internal waves: sensitivity to environmental conditions and space-time scales of internal waves.

Science.gov (United States)

Colosi, John A

2008-09-01

While many results have been intuited from numerical simulation studies, the precise connections between shallow-water acoustic variability and the space-time scales of nonlinear internal waves (NLIWs) as well as the background environmental conditions have not been clearly established analytically. Two-dimensional coupled mode propagation through NLIWs is examined using a perturbation series solution in which each order n is associated with nth-order multiple scattering. Importantly, the perturbation solution gives resonance conditions that pick out specific NLIW scales that cause coupling, and seabed attenuation is demonstrated to broaden these resonances, fundamentally changing the coupling behavior at low frequency. Sound-speed inhomogeneities caused by internal solitary waves (ISWs) are primarily considered and the dependence of mode coupling on ISW amplitude, range width, depth structure, location relative to the source, and packet characteristics are delineated as a function of acoustic frequency. In addition, it is seen that significant energy transfer to modes with initially low or zero energy involves at least a second order scattering process. Under moderate scattering conditions, comparisons of first order, single scattering theoretical predictions to direct numerical simulation demonstrate the accuracy of the approach for acoustic frequencies upto 400 Hz and for single as well as multiple ISW wave packets.

A hydrodynamic model of nearshore waves and wave-induced currents

Directory of Open Access Journals (Sweden)

Ahmed Khaled Seif

2011-09-01

Full Text Available In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995 and Larson and Kraus (2002. Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF basin and the Hazaki Oceanographical Research Station (HORS. Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

Deep-water bedforms induced by refracting Internal Solitary Waves

Science.gov (United States)

Falcini, Federico; Droghei, Riccardo; Casalbore, Daniele; Martorelli, Eleonora; Mosetti, Renzo; Sannino, Gianmaria; Santoleri, Rosalia; Latino Chiocci, Francesco

2017-04-01

Subaqueous bedforms (or sand waves) are typically observed in those environments that are exposed to strong currents, characterized by a dominant unidirectional flow. However, sand-wave fields may be also observed in marine environments where no such current exists; the physical processes driving their formation are enigmatic or not well understood. We propose that internal solitary waves (ISWs), induced by tides, can produce an effective, unidirectional boundary flow filed that forms asymmetric sand waves. We test this idea by examining a sand-wave field off the Messina Strait, where we hypothesize that ISWs formed at the interface between intermediate and surface waters are refracted by topography. Hence, we argue that the deflected pattern (i.e., the depth-dependent orientation) of the sand-wave field is due to refraction of such ISWs. Combining field observations and numerical modelling, we show that ISWs can account for three key features: ISWs produce fluid velocities capable of mobilizing bottom sediments; the predicted refraction pattern resulting from the interaction of ISWs with bottom topography matches the observed deflection of the sand waves; and predicted migration rates of sand waves match empirical estimates. This work shows how ISWs may contribute to sculpting the structure of continental margins and it represents a promising link between the geological and oceanographic communities.

First Year Observations of Antarctic Circumpolar Current Variability and Internal Wave Activity from the DIMES Mooring Array

Science.gov (United States)

Brearley, J. A.; Sheen, K. L.; Naveira-Garabato, A. C.

2012-04-01

A key component of DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) is the deployment of a two-year cross-shaped mooring array in the Antarctic Circumpolar Current to the east of Drake Passage close to 57°W. Motivation for the cluster arises from the need to understand how eddies dissipate in the Southern Ocean, and specifically how much energy is extracted from the mesoscale by breaking internal waves, which in turn leads to turbulent mixing. The location of the mooring cluster was chosen to fulfil these objectives, being situated in a region of pronounced finestructure with high eddy kinetic energy and rough topography. The array, comprising 34 current meters and Microcats and a downward-looking ADCP, was first deployed in December 2009 and serviced in December 2010. Time series of current meter results from the most heavily-instrumented 'C' mooring indicate that a strong (up to 80 cms-1) surface-intensified north-eastward directed ACC occupies the region for most of the year, with over 85% of the variability in current speed being accounted for by equivalent barotropic fluctuations. A strong mean poleward heat flux is observed at the site, which compares favourably in magnitude with literature results from other ACC locations. Interestingly, four episodes of mid-depth (~2000 m) current speed maxima, each of a few days duration, were found during the 360-day time series, a situation also observed by the lowered ADCP during mooring servicing in December 2010. Early results indicate that these episodes, which coincide with time minima in stratification close to 2000 m, could profoundly influence the nature of eddy-internal wave interactions at these times. Quantification of the energy budget at the mooring cluster has been a key priority. When compared with previous moorings located in Drake Passage (Bryden, 1977), a near threefold-increase in mean eddy kinetic energy (EKE) is observed despite a small reduction in the mean kinetic energy

Homogeneous internal wave turbulence driven by tidal flows

Science.gov (United States)

Le Reun, Thomas; Favier, Benjamin; Le Bars, Michael; Erc Fludyco Team

2017-11-01

We propose a novel investigation of the stability of strongly stratified planetary fluid layers undergoing periodic tidal distortion in the limit where rotational effects are negligible compared to buoyancy. With the help of a local model focusing on a small fluid area compared to the global layer, we find that periodic tidal distortion drives a parametric subharmonic resonance of internal. This instability saturates into an homogeneous internal wave turbulence pervading the whole fluid interior: the energy is injected in the unstable waves which then feed a succession of triadic resonances also generating small spatial scales. As the timescale separation between the forcing and Brunt-Väisälä is increased, the temporal spectrum of this turbulence displays a -2 power law reminiscent of the Garrett and Munk spectrum measured in the oceans (Garett & Munk 1979). Moreover, in this state consisting of a superposition of waves in weak non-linear interaction, the mixing efficiency is increased compared to classical, Kolmogorov-like stratified turbulence. This study is of wide interest in geophysical fluid dynamics ranging from oceanic turbulence and tidal heating in icy satellites to dynamo action in partially stratified planetary cores as it could be the case in the Earth. We acknowledge support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG).

Laboratory and numerical simulation of internal wave attractors and their instability.

Science.gov (United States)

Brouzet, Christophe; Dauxois, Thierry; Ermanyuk, Evgeny; Joubaud, Sylvain; Sibgatullin, Ilias

2015-04-01

Internal wave attractors are formed as result of focusing of internal gravity waves in a confined domain of stably stratified fluid due to peculiarities of reflections properties [1]. The energy injected into domain due to external perturbation, is concentrated along the path formed by the attractor. The existence of attractors was predicted theoretically and proved both experimentally and numerically [1-4]. Dynamics of attractors is greatly influenced by geometrical focusing, viscous dissipation and nonlinearity. The experimental setup features Schmidt number equal to 700 which impose constraints on resolution in numerical schemes. Also for investigation of stability on large time intervals (about 1000 periods of external forcing) numerical viscosity may have significant impact. For these reasons, we have chosen spectral element method for investigation of this problem, what allows to carefully follow the nonlinear dynamics. We present cross-comparison of experimental observations and numerical simulations of long-term behavior of wave attractors. Fourier analysis and subsequent application of Hilbert transform are used for filtering of spatial components of internal-wave field [5]. The observed dynamics shows a complicated coupling between the effects of local instability and global confinement of the fluid domain. The unstable attractor is shown to act as highly efficient mixing box providing the efficient energy pathway from global-scale excitation to small-scale wave motions and mixing. Acknowledgement, IS has been partially supported by Russian Ministry of Education and Science (agreement id RFMEFI60714X0090) and Russian Foundation for Basic Research, grant N 15-01-06363. EVE gratefully acknowledges his appointment as a Marie Curie incoming fellow at Laboratoire de physique ENS de Lyon. This work has been partially supported by the ONLITUR grant (ANR-2011-BS04-006-01) and achieved thanks to the resources of PSMN from ENS de Lyon 1. Maas, L. R. M. & Lam, F

Numerical Simulation of a Seaway with Breaking

Science.gov (United States)

Dommermuth, Douglas; O'Shea, Thomas; Brucker, Kyle; Wyatt, Donald

2012-11-01

The focus of this presentation is to describe the recent efforts to simulate a fully non-linear seaway with breaking by using a high-order spectral (HOS) solution of the free-surface boundary value problem to drive a three-dimensional Volume of Fluid (VOF) solution. Historically, the two main types of simulations to simulate free-surface flows are the boundary integral equations method (BIEM) and high-order spectral (HOS) methods. BIEM calculations fail at the point at which the surface impacts upon itself, if not sooner, and HOS methods can only simulate a single valued free-surface. Both also employ a single-phase approximation in which the effects of the air on the water are neglected. Due to these limitations they are unable to simulate breaking waves and air entrainment. The Volume of Fluid (VOF) method on the other hand is suitable for modeling breaking waves and air entrainment. However it is computationally intractable to generate a realistic non-linear sea-state. Here, we use the HOS solution to quickly drive, or nudge, the VOF solution into a non-linear state. The computational strategies, mathematical formulation, and numerical implementation will be discussed. The results of the VOF simulation of a seaway with breaking will also be presented, and compared to the single phase, single valued HOS results.

Nonlinear internal gravity waves and their interaction with the mean wind

International Nuclear Information System (INIS)

Grimshaw, R.

1975-01-01

The interaction of a wave packet of internal gravity waves with the mean wind is investigated, for the case when there is a region of wind shear and hence a critical level. The principal equations are the Doppler-shifted dispersion relation, the equation for conservation of wave action and the mean momentum equation, in which the mean wind is accelerated by a 'radiation stress' tensor, due to the waves. These equations are integrated numerically to study the behaviour of a wave packet approaching a critical level, where the horizontal phase speed matches the mean wind. The results demonstrate the exchange of energy from the waves to the mean wind in the vicinity of the critical level. The interaction between the waves and the mean wind is also studied in the absence of any initial wind shear. (author)

On the generation and evolution of internal solitary waves in the southern Red Sea

KAUST Repository

Guo, Daquan

2015-04-01

Satellite observations recently revealed the existence of trains of internal solitary waves in the southern Red Sea between 16.0°N and 16.5°N, propagating from the centre of the domain toward the continental shelf [Da silva et al., 2012]. Given the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial tides by impinging, remotely generated internal tidal beams and for geometrically focused and amplified internal tidal beams. Tide analysis based on tide stations data and barotropic tide model in the Red Sea shows that tide is indeed very weak in the centre part of the Red Sea, but it is relatively strong in the northern and southern parts (reaching up to 66 cm/s). Together with extreme steep slopes along the deep trench, it provides favourable conditions for the generation of internal solitary in the southern Red Sea. To investigate the generation mechanisms and study the evolution of the internal waves in the off-shelf region of the southern Red Sea we have implemented a 2-D, high-resolution and non-hydrostatic configuration of the MIT general circulation model (MITgcm). Our simulations reproduce well that the generation process of the internal solitary waves. Analysis of the model\\'s output suggests that the interaction between the topography and tidal flow with the nonlinear effect is the main mechanism behind the generation of the internal solitary waves. Sensitivity experiments suggest that neither tidal beam nor the resonance effect of the topography is important factor in this process.

Ocean wave generation by collapsing ice shelves

Science.gov (United States)

Macayeal, D. R.; Bassis, J. N.; Okal, E. A.; Aster, R. C.; Cathles, L. M.

2008-12-01

The 28-29 February, 2008, break-up of the Wilkins Ice Shelf, Antarctica, exemplifies the now-familiar, yet largely unexplained pattern of explosive ice-shelf break-up. While environmental warming is a likely ultimate cause of explosive break-up, several key aspects of their short-term behavior need to be explained: (1) The abrupt, near-simultaneous onset of iceberg calving across long spans of the ice front margin; (2) High outward drift velocity (about 0.3 m/s) of a leading phalanx of tabular icebergs that originate from the seaward edge of the intact ice shelf prior to break-up; (3) Rapid coverage of the ocean surface in the wake of this leading phalanx by small, capsized and dismembered tabular icebergs; (4) Extremely large gravitational potential energy release rates, e.g., up to 3 × 1010 W; (5) Lack of proximal iceberg-calving triggers that control the timing of break-up onset and that maintain the high break-up calving rates through to the conclusion of the event. Motivated by seismic records obtained from icebergs and the Ross Ice Shelf that show hundreds of micro- tsunamis emanating from near the ice shelf front, we re-examine the basic dynamic features of ice- shelf/ocean-wave interaction and, in particular, examine the possibility that collapsing ice shelves themselves are a source of waves that stimulate the disintegration process. We propose that ice-shelf generated surface-gravity waves associated with initial calving at an arbitrary seed location produce stress perturbations capable of triggering the onset of calving on the entire ice front. Waves generated by parting detachment rifts, iceberg capsize and break-up act next to stimulate an inverted submarine landslide (ice- slide) process, where gravitational potential energy released by upward movement of buoyant ice is radiated as surface gravity waves in the wake of the advancing phalanx of tabular icebergs. We conclude by describing how field research and remote sensing can be used to test the

Identification of internal waves off Visakhapatnam from Thermister chain

Digital Repository Service at National Institute of Oceanography (India)

Murty, T.V.R.; Rao, M.M.M.; Sadhuram, Y.; SujitKumar, S.; SaiSandhya, K.; Maneesha, K.; Murthy, K.S.R.

An analysis of Internal Wave (IW) signatures by in-situ observations off Visakhapatnam has been presented to study the impact of IWs on acoustic field. Temperature data were collected for 44 hours at an interval of 2 minutes off Visakhapatnam (17...

Surface and Internal Waves due to a Moving Load on a Very Large Floating Structure

Directory of Open Access Journals (Sweden)

Taro Kakinuma

2012-01-01

Full Text Available Interaction of surface/internal water waves with a floating platform is discussed with nonlinearity of fluid motion and flexibility of oscillating structure. The set of governing equations based on a variational principle is applied to a one- or two-layer fluid interacting with a horizontally very large and elastic thin plate floating on the water surface. Calculation results of surface displacements are compared with the existing experimental data, where a tsunami, in terms of a solitary wave, propagates across one-layer water with a floating thin plate. We also simulate surface and internal waves due to a point load, such as an airplane, moving on a very large floating structure in shallow water. The wave height of the surface or internal mode is amplified when the velocity of moving point load is equal to the surface- or internal-mode celerity, respectively.

Internal wave focusing revisited; a reanalysis and new theoretical links

International Nuclear Information System (INIS)

Lam, Frans-Peter A; Maas, Leo R M

2008-01-01

An experiment which discussed the appearance of an internal wave attractor in a uniformly stratified, free-surface fluid [Maas, L.R.M., Benielli, D., Sommeria, J., Lam, F.-P.A., 1997. Observation of an internal wave attractor in a confined, stably stratified fluid. Nature 388(6642), 557-561] is revisited. This is done in order to give a more detailed and more accurate description of the underlying focusing process. Evolution of the attractor can now be quantified. For the tank with one sloping sidewall, and for the parameter regime (density stratification, forcing frequency) studied, the inverse exponential growth rate determined at several locations in the fluid turns out to be 122 s always. Only the start and duration of the growth differed: away from the attractor region it appeared later and of shorter duration. Here, these features are interpreted by employing a new theoretical basis that incorporates an external forcing via a surface boundary condition (an infinitesimal barotropic seiche) and that describes the solution in terms of propagating waves.

Infragravity Waves Produced by Wave Groups on Beaches

Institute of Scientific and Technical Information of China (English)

邹志利; 常梅

2003-01-01

The generation of low frequency waves by a single or double wave groups incident upon two plane beaches with the slope of 1/40 and 1/100 is investigated experimentally and numerically. A new type of wave maker signal is used to generate the groups, allowing the bound long wave (set-down) to be included in the group. The experiments show that the low frequency wave is generated during breaking and propagation to the shoreline of the wave group. This process of generation and propagation of low frequency waves is simulated numerically by solving the short-wave averaged mass and momentum conservation equations. The computed and measured results are in good agreement. The mechanism of generation of low frequency waves in the surf zone is examined and discussed.

On the Chemical Mixing Induced by Internal Gravity Waves

Energy Technology Data Exchange (ETDEWEB)

Rogers, T. M. [School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne (United Kingdom); McElwaine, J. N. [Planetary Science Institute, Tucson, AZ 85721 (United States)

2017-10-10

Detailed modeling of stellar evolution requires a better understanding of the (magneto)hydrodynamic processes that mix chemical elements and transport angular momentum. Understanding these processes is crucial if we are to accurately interpret observations of chemical abundance anomalies, surface rotation measurements, and asteroseismic data. Here, we use two-dimensional hydrodynamic simulations of the generation and propagation of internal gravity waves in an intermediate-mass star to measure the chemical mixing induced by these waves. We show that such mixing can generally be treated as a diffusive process. We then show that the local diffusion coefficient does not depend on the local fluid velocity, but rather on the wave amplitude. We then use these findings to provide a simple parameterization for this diffusion, which can be incorporated into stellar evolution codes and tested against observations.

Effects of the Pressurized Water Reactor Main Steam Line Break Location on the Blowdown Loading

International Nuclear Information System (INIS)

Jo, Jong Chull; Kang, Soon Ho; Chan, Won Joon

2016-01-01

The thermal hydraulic analysis has been performed generally using a simple lumped model or one dimensional numerical model. However, those models have limitations in predicting the transient variations of the steam velocity, pressure and hydrodynamic load at a local point and the most conservative condition. Furthermore, it cannot be confirmed if the blowdown loads predicted by either of the models are conservative to evaluate every part of the SG internal structures. In this study, the transient hydraulic response of the SG secondary side to the MSLB case where the pipe break is assumed to occur at the SG outlet nozzle end, another weld point on the MSL, was numerically simulated using a CFD code. The present CFD calculation results was compared with those in ref. to investigate the effect of break location (friction loss) on the blowdown load in the SG secondary side. The result shows that the friction loss along the steam line span between the SG nozzle end and the MSIV would cause reduction in steam velocity disturbance or dynamic pressure. It implies that the consequence of the MSLB at the SG nozzle end would be much severer that those of other MSLB cases where the break locations are far from the SG. Therefore, to assure a conservative safety evaluation of the SG structural integrity, the blowdown loading on the SG internal structures including tubes during a MSLB accident in terms of the transient steam velocity, dynamic pressure and decompression wave fluctuations should be assessed for the MSLB case where the break is assumed to occur at the SG nozzle end.

Effects of the Pressurized Water Reactor Main Steam Line Break Location on the Blowdown Loading

Energy Technology Data Exchange (ETDEWEB)

Jo, Jong Chull; Kang, Soon Ho; Chan, Won Joon [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The thermal hydraulic analysis has been performed generally using a simple lumped model or one dimensional numerical model. However, those models have limitations in predicting the transient variations of the steam velocity, pressure and hydrodynamic load at a local point and the most conservative condition. Furthermore, it cannot be confirmed if the blowdown loads predicted by either of the models are conservative to evaluate every part of the SG internal structures. In this study, the transient hydraulic response of the SG secondary side to the MSLB case where the pipe break is assumed to occur at the SG outlet nozzle end, another weld point on the MSL, was numerically simulated using a CFD code. The present CFD calculation results was compared with those in ref. to investigate the effect of break location (friction loss) on the blowdown load in the SG secondary side. The result shows that the friction loss along the steam line span between the SG nozzle end and the MSIV would cause reduction in steam velocity disturbance or dynamic pressure. It implies that the consequence of the MSLB at the SG nozzle end would be much severer that those of other MSLB cases where the break locations are far from the SG. Therefore, to assure a conservative safety evaluation of the SG structural integrity, the blowdown loading on the SG internal structures including tubes during a MSLB accident in terms of the transient steam velocity, dynamic pressure and decompression wave fluctuations should be assessed for the MSLB case where the break is assumed to occur at the SG nozzle end.

Spatio-temporal variability of internal waves in the northern Gulf of Mexico studied with the Navy Coastal Ocean Model, NCOM

Science.gov (United States)

Cambazoglu, M. K.; Jacobs, G. A.; Howden, S. D.; Book, J. W.; Arnone, R.; Soto Ramos, I. M.; Vandermeulen, R. A.; Greer, A. T.; Miles, T. N.

2016-02-01

Internal waves enhance mixing in the upper ocean, transport nutrients and plankton over the water column and across the shelf from deeper waters to shallower coastal areas, and could also transport pollutants such as hydrocarbons onshore during an oil spill event. This study aims to characterize internal waves in the northern Gulf of Mexico (nGoM) and investigate the possible generation and dissipation mechanisms using a high-resolution (1-km) application of the Navy Coastal Ocean Model (NCOM). Three dimensional model products are used to detect the propagation patterns of internal waves. The vertical structure of internal waves is studied and the role of stratification is analyzed by looking at the temperature, salinity and velocity variations along the water column. The model predictions suggest the generation of internal waves on the continental shelf, therefore the role of ocean bottom topography interacting with tides and general circulation features such as the Loop Current Eddy front, on the internal wave generation will be discussed. The time periods of internal wave occurrences are identified from model predictions and compared to satellite ocean color imagery. Further data analysis, e.g. Fourier analysis, is implemented to determine internal wavelengths and frequencies and to determine if the response of internal waves are at tidal periods or at different frequencies. The atmospheric forcing provided to NCOM and meteorological data records are analyzed to define the interaction between wind forcing and internal wave generation. Wavelet analysis characterizes the ocean response to atmospheric events with periodic frequencies. Ocean color satellite imagery was used to visualize the location of the Mississippi river plume (and other oceanic features) and compared to the model predictions because the enhanced stratification from freshwater plumes which propagate across the Mississippi Bight can provide favorable conditions in coastal waters for internal wave

A simplified method of evaluating the stress wave environment of internal equipment

Science.gov (United States)

Colton, J. D.; Desmond, T. P.

1979-01-01

A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.

Implications of career break from personal and company perspectives

OpenAIRE

Vuorinen, Niina

2017-01-01

The objective of this study is to show the implications that career breaks have on individuals and employers. The intensions are to identify personal motivations for career breaks, and if the breaks change the careers of the people taking them. Furthermore, this study intends to understand how career breaks are viewed by employers, and if career breaks are becoming more acceptable internationally. The theoretical framework was based on description of work and careers both from employee an...

Assessment of the critical neutron number for internal break-even in explosion-induced thermonuclear fusion

International Nuclear Information System (INIS)

Kaliski, S.

1979-01-01

An analysis is performed of the systems of an explosion-induced thermonuclear microfusion from the angle of attaining an internal break-even. A critical-state meter is defined, i.e. the critical neutron yield Nsub(cr) as the most convenient for characterizing the experimental setups. It is demonstrated that in a number of designed systems of an explosion-induced microfusion, Nsub(cr) is attained. In the experiments actually carried out the N-yield efficiency is of about three orders of magnitude. (author)

TWO-DIMENSIONAL MODELLING OF ACCIDENTAL FLOOD WAVES PROPAGATION

OpenAIRE

Lorand Catalin STOENESCU

2011-01-01

The study presented in this article describes a modern modeling methodology of the propagation of accidental flood waves in case a dam break; this methodology is applied in Romania for the first time for the pilot project „Breaking scenarios of Poiana Uzului dam”. The calculation programs used help us obtain a bidimensional calculation (2D) of the propagation of flood waves, taking into consideration the diminishing of the flood wave on a normal direction to the main direction; this diminishi...

The impact of seasonal changes in stratification on the dynamics of internal waves in the Sea of Okhotsk

Directory of Open Access Journals (Sweden)

Oxana E. Kurkina

2017-11-01

Full Text Available The properties and dynamics of internal waves in the ocean crucially depend on the vertical structure of water masses. We present detailed analysis of the impact of spatial and seasonal variations in the density-driven stratification in the Sea of Okhotsk on the properties of the classic kinematic and nonlinear parameters of internal waves in this water body. The resulting maps of the phase speed of long internal waves and coefficients at various terms of the underlying Gardner’s equation make it possible to rapidly determine the main properties of internal solitary waves in the region and to choose an adequate set of parameters of the relevant numerical models. It is shown that the phase speed of long internal waves almost does not depend on the particular season. The coefficient at the quadratic term of the underlying evolution equation is predominantly negative in summer and winter and therefore internal solitons usually have negative polarity. Numerical simulations of the formation of internal solitons and solibores indicate that seasonal variations in the coefficient at the cubic term of Gardner’s equation lead to substantial variations in the shape of solibores.

Joint trajectories for social and physical aggression as predictors of adolescent maladjustment: Internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features

Science.gov (United States)

UNDERWOOD, MARION K.; BERON, KURT J.; ROSEN, LISA H.

2011-01-01

This investigation examined the relation between developmental trajectories jointly estimated for social and physical aggression and adjustment problems at age 14. Teachers provided ratings of children's social and physical aggression in Grades 3, 4, 5, 6, and 7 for a sample of 255 children (131 girls, 21% African American, 52% European American, 21% Mexican American). Participants, parents, and teachers completed measures of the adolescent's adjustment to assess internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. Results showed that membership in a high and rising trajectory group predicted rule-breaking behaviors and borderline personality features. Membership in a high desister group predicted internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. The findings suggest that although low levels of social and physical aggression may not bode poorly for adjustment, individuals engaging in high levels of social and physical aggression in middle childhood may be at greatest risk for adolescent psychopathology, whether they increase or desist in their aggression through early adolescence. PMID:21532919

DAM-BREAK SHOCK WAVES WITH FLOATING DEBRIS: EXPERIMENTALANALYSIS AND TWO-PHASE MODELLING

Directory of Open Access Journals (Sweden)

Stefano Mambretti

2008-06-01

Full Text Available To predict floods and debris flow dynamics a numerical model, based on 1D De Saint Venant (SV equations, was developed. The McCormack – Jameson shock capturing scheme was employed for the solution of the equations, written in a conservative law form. This technique was applied to determine both the propagation and the profile of a two – phase debris flow resulting from the instantaneous and complete collapse of a storage dam. To validate the model, comparisons have been made between its predictions and laboratory measurements concerning flows of water and homogeneous granular mixtures in a uniform geometry flume reproducing dam – break waves. Agreements between computational and experimental results are considered very satisfactory for mature (non – stratified debris flows, which embrace most real cases. To better predict immature (stratified flows, the model should be improved in order to feature, in a more realistic way, the distribution of the particles of different size within the mixture. On the whole, the model proposed can easily be extended to channels with arbitrary cross sections for debris flow routing, as well as for solving different problems of unsteady flow in open channels by incorporating the appropriate initial and boundary conditions.

Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.

Science.gov (United States)

Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F

2011-04-01

Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.

Shoaling internal solitary waves of depression over gentle slopes

Science.gov (United States)

Rivera, Gustavo; Diamessis, Peter

2017-11-01

The shoaling of an internal solitary wave (ISW) of depression over gentle slopes is explored through fully nonlinear and non-hydrostatic simulations using a high resolution/accuracy deformed spectral multidomain penalty method. During shoaling, the wave does not disintegrate as in the case of steeper slope but, instead, maintains its symmetric shape. At the core of the wave, an unstable region forms, characterized by the entrapment of heavier-over-light fluid. The formation of this convective instability is attributed to the vertical stretching by the ISW of the near-surface vorticity layer associated with the baroclinic background current. According to recent field observations in the South China Sea, the unstable region drives localized turbulent mixing within the wave, estimated to be up to four times larger than that in the open ocean, in the form of a recirculating trapped core. In this talk, emphasis is placed on the structure of the unstable region and the persistence of a possible recirculating core using simulations which capture 2D wave propagation combined with 3D representation of the transition to turbulence. As such, a preliminary understanding of the underlying fluid mechanics and the potential broader oceanic significance of ISWs with trapped cores is offered. Financial support gratefully acknowledged to NSF OCE Grant 1634257.

Kinematics and dynamics of green water on a fixed platform in a large wave basin in focusing wave and random wave conditions

Science.gov (United States)

Chuang, Wei-Liang; Chang, Kuang-An; Mercier, Richard

2018-06-01

Green water kinematics and dynamics due to wave impingements on a simplified geometry, fixed platform were experimentally investigated in a large, deep-water wave basin. Both plane focusing waves and random waves were employed in the generation of green water. The focusing wave condition was designed to create two consecutive plunging breaking waves with one impinging on the frontal vertical wall of the fixed platform, referred as wall impingement, and the other directly impinging on the deck surface, referred as deck impingement. The random wave condition was generated using the JONSWAP spectrum with a significant wave height approximately equal to the freeboard. A total of 179 green water events were collected in the random wave condition. By examining the green water events in random waves, three different flow types are categorized: collapse of overtopping wave, fall of bulk water, and breaking wave crest. The aerated flow velocity was measured using bubble image velocimetry, while the void fraction was measured using fiber optic reflectometry. For the plane focusing wave condition, measurements of impact pressure were synchronized with the flow velocity and void fraction measurements. The relationship between the peak pressures and the pressure rise times is examined. For the high-intensity impact in the deck impingement events, the peak pressures are observed to be proportional to the aeration levels. The maximum horizontal velocities in the green water events in random waves are well represented by the lognormal distribution. Ritter's solution is shown to quantitatively describe the green water velocity distributions under both the focusing wave condition and the random wave condition. A prediction equation for green water velocity distribution under random waves is proposed.

Experimental Study of the Effect of Internal Defects on Stress Waves during Automated Fiber Placement

Directory of Open Access Journals (Sweden)

Zhenyu Han

2018-04-01

Full Text Available The detection technique of component defects is currently only realized to detect offline defects and online surface defects during automated fiber placement (AFP. The characteristics of stress waves can be effectively applied to identify and detect internal defects in material structure. However, the correlation mechanism between stress waves and internal defects remains unclear during the AFP process. This paper proposes a novel experimental method to test stress waves, where continuous loading induced by process itself is used as an excitation source without other external excitation. Twenty-seven groups of thermosetting prepreg laminates under different processing parameters are manufactured to obtain different void content. In order to quantitatively estimate the void content in the prepreg structure, the relation model between the void content and ultrasonic attenuation coefficient is revealed using an A-scan ultrasonic flaw detector and photographic methods by optical microscope. Furthermore, the high-frequency noises of stress waves are removed using Haar wavelet transform. The peaks, the Manhattan distance and mean stress during the laying process are analyzed and evaluated. Partial conclusions in this paper could provide theoretical support for online real-time detection of internal defects based on stress wave characteristics.

On the detectability of internal waves by an imaging lidar

NARCIS (Netherlands)

Magalhaes, J.M.; da Silva, J.C.B.; Batista, M.; Gostiaux, L.; Gerkema, T.; New, A.L.; Jeans, D.R.G.

2013-01-01

The first results of a multisensor airborne survey conducted off the western Iberian Coast are presented (including visible, lidar, and infrared imagery) and reveal the presence of internal solitary waves (ISWs) propagating into the nearshore region. For the first time, two-dimensional lidar imagery

Structural analysis of steam generator internals following feed water main steam line break: DLF approach

International Nuclear Information System (INIS)

Bhasin, Vivek; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

1993-01-01

In order to evaluate the possible release of radioactivity in extreme events, some postulated accidents are analysed and studied during the design stage of Steam Generator (SG). Among the various accidents postulated, the most important are Feed Water Line Break (FWLB) and Main Steam Line Break (MSLB). This report concerns with dynamic structural analysis of SG internals following FWLB/MSLB. The pressure/drag-force time histories considered were corresponding to the conditions leading to the accident of maximum potential. The SG internals were analysed using two approaches of structural dynamics. In first approach simplified DLF method was adopted. This method yields an upper bound values of stresses and deflection. In the second approach time history analysis by Mode Superposition Technique was adopted. This approach gives more realistic results. The structure was qualified as per ASME B and PV Code SecIII NB. It was concluded that in all the components except perforated flow distribution plate, the stress values based on elastic analysis are within the limits specified by ASME Code. In case of perforated flow distribution plate during the MSLB transient the stress values based on elastic analysis are higher than the ASME Code limits. Therefore, its limit load analysis had to be done. Finally, the collapse pressure evaluated using limit load analysis was shown to be within the limits of ASME B and PV Code SecIII Nb. (author). 31 refs., 94 figs., 16 tabs

International shock-wave database project : report of the requirements workshop.

Energy Technology Data Exchange (ETDEWEB)

Aidun, John Bahram (Institute of Problems of chemical Physics of Russian Academy of Sciences); Lomonosov, Igor V. (Institute of Problems of chemical Physics of Russian Academy of Sciences); Levashov, Pavel R. (Joint Institute for High Temperatures of Russian Academy of Sciences)

2012-03-01

We report on the requirements workshop for a new project, the International Shock-Wave database (ISWdb), which was held October 31 - November 2, 2011, at GSI, Darmstadt, Germany. Participants considered the idea of this database, its structure, technical requirements, content, and principles of operation. This report presents the consensus conclusions from the workshop, key discussion points, and the goals and plan for near-term and intermediate-term development of the ISWdb. The main points of consensus from the workshop were: (1) This international database is of interest and of practical use for the shock-wave and high pressure physics communities; (2) Intermediate state information and off-Hugoniot information is important and should be included in ISWdb; (3) Other relevant high pressure and auxiliary data should be included to the database, in the future; (4) Information on the ISWdb needs to be communicated, broadly, to the research community; and (5) Operating structure will consist of an Advisory Board, subject-matter expert Moderators to vet submitted data, and the database Project Team. This brief report is intended to inform the shock-wave research community and interested funding agencies about the project, as its success, ultimately, depends on both of these groups finding sufficient value in the database to use it, contribute to it, and support it.

Modeling internal wave generation by seamounts in oceans

Science.gov (United States)

Zhang, L.; Buijsman, M. C.; Comino, E. L.; Swinney, H.

2017-12-01

Recent global bathymetric data at 30 arc-sec resolution has revealed that there are 33,452 seamounts and 138,412 knolls in the oceans. To develop an estimate for the energy converted from tidal flow to internal gravity waves, we have conducted numerical simulations using the Massachusetts Institute of Technology circulation model (MITgcm) to compute the energy conversion by randomly distributed Gaussian-shaped seamounts. We find that for an isolated axisymmetric seamount of height 1100 m and radius 1600 m, which corresponds to the Wessel height-to-radius ratio 0.69, the conversion rate is 100 kW, assuming a tidal speed amplitude 1 cm/s, buoyancy frequency 1e-3 rad/s, and circularly polarized tidal motion, and taking into account the earth's rotation. The 100 kW estimate is about 60% less than the 3-D linear theory prediction because fluid goes around a seamount instead of over it. Our estimate accounts the suppression of energy conversion due to wave interference at the generation site of closely spaced seamounts. We conclude that for randomly distributed Gaussian seamounts of varying widths and separations, separated on average by 18 km as in the oceans, wave interference reduces the energy conversion by seamounts by only about 16%. This result complements previous studies of wave interference for 2-D ridges.

On the generation and evolution of internal solitary waves in the southern Red Sea

KAUST Repository

Guo, Daquan; Akylas, T. R.; Zhan, Peng; Kartadikaria, Aditya R.; Hoteit, Ibrahim

2016-01-01

Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0 degrees N and 16.5 degrees N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though

Experimental and numerical investigation of the internal kinetics of a surf-zone plunging breaker

DEFF Research Database (Denmark)

Emarat, Narumon; Forehand, David I.M.; Christensen, Erik Damgaard

2012-01-01

Over the last couple of decades both the qualitative and quantitative understanding of breaking waves in the surf zone have greatly increased. This is due to the advances in experimental and numerical techniques. However, few comparisons between these two different investigative techniques...... for surfzone breaking waves have been reported. In this study, a comparison is made between the experimental and numerical investigation of the internal kinematics of a surf-zone plunging breaker. The full-field velocity measuring technique known as Particle Image Velocimetry (PIV) is used in the experiments...... was found for all comparisons: free-surface elevations, velocity vector maps, velocity profiles and velocity-magnitude contours. However, some small discrepancies were observed. In the free-surface elevation comparisons, a slight time lag was observed in the numerical results and it is suggested...

Internal waves and modern and ancient hiatuses in pelagic caps of Pacific guyots and seamounts

Science.gov (United States)

Mitchell, Neil; Simmons, Harper; Lear, Carrie

2013-04-01

Locations of recent non-deposition and ancient hiatuses in the pelagic caps of guyots and seamounts are compared with paleotemperature and physiographic information to speculate on the character of internal tidal waves in the upper Pacific Ocean through the Cenozoic. Internal tidal waves are generated where the ocean barotropic tide passes over the Hawaiian and other major ridges in the Pacific basin. Drill core and geophysical evidence for sediment accumulation, non-deposition or erosion are used to classify broadly sites as either accumulating or eroding/non-depositing in the recent geological past. When these classified sites are compared against results of a numerical model of the internal tide field (Simmons, Ocean Mod. 2008), the sites accumulating particles over the past few million years are all found to lie away from beams of the modeled internal tide, while those that have not been accumulating are in areas of high internal wave energy. Given the correspondence to modern internal wave conditions, we examine whether internal tides can explain ancient hiatuses at the drill sites. For example, Late Cenozoic pelagic caps on guyots among the Marshall Islands contain two hiatuses of broadly similar age, but the dates of the first pelagic sediments deposited following each hiatus do not correlate between guyots, suggesting that they originate not from universal factors (e.g., water chemistry) but local, probably physical factors, such as internal tides. We investigate how changing boundary conditions such as ocean temperature and basin physiography may have affected the geometry and vigour of internal tides through the Cenozoic. Changes in the geometry of ridges underlying the Solomon, Bonin and Marianas Island chains caused by plate tectonics and subsidence may be responsible for sediment hiatuses at these far-field guyot sites.

Influence of Complete Coriolis Force on the Dispersion Relation of Ocean Internal-wave in a Background Currents Field

Directory of Open Access Journals (Sweden)

Liu Yongjun

2015-01-01

Full Text Available In this thesis, the influence of complete Coriolis force (the model includes both the vertical and horizontal components of Coriolis force on the dispersion relation of ocean internal-wave under background currents field are studied, it is important to the study of ocean internal waves in density-stratified ocean. We start from the control equation of sea water movement in the background of the non-traditional approximation, and the vertical velocity solution is derived where buoyancy frequency N(z gradually varies with the ocean depth z. The results show that the influence of complete Coriolis force on the dispersion relation of ocean internal-wave under background currents field is obvious, and these results provide strong evidence for the understanding of dynamic process of density stratified ocean internal waves.

Large-amplitude internal tides, solitary waves, and turbulence in the central Bay of Biscay

Science.gov (United States)

Xie, X. H.; Cuypers, Y.; Bouruet-Aubertot, P.; Ferron, B.; Pichon, A.; LourençO, A.; Cortes, N.

2013-06-01

and fine-scale measurements collected in the central Bay of Biscay during the MOUTON experiment are analyzed to investigate the dynamics of internal waves and associated mixing. Large-amplitude internal tides (ITs) that excite internal solitary waves (ISWs) in the thermocline are observed. ITs are dominated by modes 3 and 4, while ISWs projected on mode 1 that is trapped in the thermocline. Therein, ITs generate a persistent narrow shear band, which is strongly correlated with the enhanced dissipation rate in the thermocline. This strong dissipation rate is further reinforced in the presence of ISWs. Dissipation rates during the period without ISWs largely agree with the MacKinnon-Gregg scaling proposed for internal wavefields dominated by a low-frequency mode, while they show poor agreement with the Gregg-Henyey parameterization valid for internal wavefields close to the Garrett-Munk model. The agreement with the MacKinnon-Gregg scaling is consistent with the fact that turbulent mixing here is driven by the low-frequency internal tidal shear.

Research for developing precise tsunami evaluation methods. Probabilistic tsunami hazard analysis/numerical simulation method with dispersion and wave breaking

International Nuclear Information System (INIS)

2007-01-01

The present report introduces main results of investigations on precise tsunami evaluation methods, which were carried out from the viewpoint of safety evaluation for nuclear power facilities and deliberated by the Tsunami Evaluation Subcommittee. A framework for the probabilistic tsunami hazard analysis (PTHA) based on logic tree is proposed and calculation on the Pacific side of northeastern Japan is performed as a case study. Tsunami motions with dispersion and wave breaking were investigated both experimentally and numerically. The numerical simulation method is verified for its practicability by applying to a historical tsunami. Tsunami force is also investigated and formulae of tsunami pressure acting on breakwaters and on building due to inundating tsunami are proposed. (author)

Spontaneous generation and reversals of mean flows in a convectively-generated internal gravity wave field

Science.gov (United States)

Couston, Louis-Alexandre; Lecoanet, Daniel; Favier, Benjamin; Le Bars, Michael

2017-11-01

We investigate via direct numerical simulations the spontaneous generation and reversals of mean zonal flows in a stably-stratified fluid layer lying above a turbulent convective fluid. Contrary to the leading idealized theories of mean flow generation by self-interacting internal waves, the emergence of a mean flow in a convectively-generated internal gravity wave field is not always possible because nonlinear interactions of waves of different frequencies can disrupt the mean flow generation mechanism. Strong mean flows thus emerge when the divergence of the Reynolds stress resulting from the nonlinear interactions of internal waves produces a strong enough anti-diffusive acceleration for the mean flow, which, as we will demonstrate, is the case when the Prandtl number is sufficiently low, or when the energy input into the internal wavefield by the convection and density stratification are sufficiently large. Implications for mean zonal flow production as observed in the equatorial stratospheres of the Earth, Saturn and Jupiter, and possibly occurring in other geophysical systems such as planetary and stellar interiors will be briefly discussed. Funding provided by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program through Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG.

On the Soft Supersymmetry Breaking Parameters in Gauge-Mediated Models

CERN Document Server

Wagner, C E M

1998-01-01

Gauge mediation of supersymmetry breaking in the observable sector is an attractive idea, which naturally alleviates the flavour changing neutral current problem of supersymmetric theories. Quite generally, however, the number and quantum number of the messengers are not known; nor is their characteristic mass scale determined by the theory. Using the recently proposed method to extract supersymmetry-breaking parameters from wave-function renormalization, we derived general formulae for the soft supersymmetry-breaking parameters in the observable sector, valid in the small and moderate $\\tan\\beta$ regimes, for the case of split messengers. The full leading-order effects of top Yukawa and gauge couplings on the soft supersymmetry-breaking parameters are included. We give a simple interpretation of the general formulae in terms of the renormalization group evolution of the soft supersymmetry-breaking parameters. As a by-product of this analysis, the one-loop renormalization group evolution of the soft supersymm...

Database of full-scale laboratory experiments on wave-driven sand transport processes

NARCIS (Netherlands)

van der Werf, Jebbe J.; Schretlen, Johanna Lidwina Maria; Ribberink, Jan S.; O'Donoghue, Tom

2009-01-01

A new database of laboratory experiments involving sand transport processes over horizontal, mobile sand beds under full-scale non-breaking wave and non-breaking wave-plus-current conditions is described. The database contains details of the flow and bed conditions, information on which quantities

One-Dimensional Mass-Spring Chains Supporting Elastic Waves with Non-Conventional Topology

Directory of Open Access Journals (Sweden)

2016-04-01

Full Text Available There are two classes of phononic structures that can support elastic waves with non-conventional topology, namely intrinsic and extrinsic systems. The non-conventional topology of elastic wave results from breaking time reversal symmetry (T-symmetry of wave propagation. In extrinsic systems, energy is injected into the phononic structure to break T-symmetry. In intrinsic systems symmetry is broken through the medium microstructure that may lead to internal resonances. Mass-spring composite structures are introduced as metaphors for more complex phononic crystals with non-conventional topology. The elastic wave equation of motion of an intrinsic phononic structure composed of two coupled one-dimensional (1D harmonic chains can be factored into a Dirac-like equation, leading to antisymmetric modes that have spinor character and therefore non-conventional topology in wave number space. The topology of the elastic waves can be further modified by subjecting phononic structures to externally-induced spatio-temporal modulation of their elastic properties. Such modulations can be actuated through photo-elastic effects, magneto-elastic effects, piezo-electric effects or external mechanical effects. We also uncover an analogy between a combined intrinsic-extrinsic systems composed of a simple one-dimensional harmonic chain coupled to a rigid substrate subjected to a spatio-temporal modulation of the side spring stiffness and the Dirac equation in the presence of an electromagnetic field. The modulation is shown to be able to tune the spinor part of the elastic wave function and therefore its topology. This analogy between classical mechanics and quantum phenomena offers new modalities for developing more complex functions of phononic crystals and acoustic metamaterials.

Observations and estimates of wave-driven water level extremes at the Marshall Islands

Science.gov (United States)

Merrifield, M. A.; Becker, J. M.; Ford, M.; Yao, Y.

2014-10-01

Wave-driven extreme water levels are examined for coastlines protected by fringing reefs using field observations obtained in the Republic of the Marshall Islands. The 2% exceedence water level near the shoreline due to waves is estimated empirically for the study sites from breaking wave height at the outer reef and by combining separate contributions from setup, sea and swell, and infragravity waves, which are estimated based on breaking wave height and water level over the reef flat. Although each component exhibits a tidal dependence, they sum to yield a 2% exceedence level that does not. A hindcast based on the breaking wave height parameterization is used to assess factors leading to flooding at Roi-Namur caused by an energetic swell event during December 2008. Extreme water levels similar to December 2008 are projected to increase significantly with rising sea level as more wave and tide events combine to exceed inundation threshold levels.

On the soft supersymmetry-breaking parameters in gauge-mediated models

International Nuclear Information System (INIS)

Wagner, C.E.M.

1998-01-01

Gauge mediation of supersymmetry breaking in the observable sector is an attractive idea, which naturally alleviates the flavor changing neutral current problem of supersymmetric theories. Quite generally, however, the number and quantum number of the messengers are not known; nor is their characteristic mass scale determined by the theory. Using the recently proposed method to extract supersymmetry-breaking parameters from wave-function renormalization, we derived general formulae for the soft supersymmetry-breaking parameters in the observable sector, valid in the small and moderate tan β regimes, for the case of split messengers. The full leading-order effects of top Yukawa and gauge couplings on the soft supersymmetry-breaking parameters are included. We give a simple interpretation of the general formulae in terms of the renormalization group evolution of the soft supersymmetry-breaking parameters. As a by-product of this analysis, the one-loop renormalization group evolution of the soft supersymmetry-breaking parameters is obtained for arbitrary boundary conditions of the scalar and gaugino mass parameters at high energies. (orig.)

Analysis of internal stress and anelasticity in the shock-compressed state from unloading wave data

International Nuclear Information System (INIS)

Johnson, J.N.; Lomdahl, P.S.; Wills, J.M.

1991-01-01

This paper reports on time resolved shock-wave measurements have often been used to infer microstructural behavior in crystalline solids. The authors apply this approach to an interpretation of the release-wave response of an aluminum alloy (6061-T6) as it is dynamically unloaded from a shock-compressed state of 20.7 GPa. The anelastic behavior in the initial portion of the unloading wave is attributed to the accumulation of internal stresses created by the shock process. Specific internal-stress models which are investigated are the double pile-up, the single pile-up, and single dislocation loops between pinning points. It is found that the essential characteristics of double and single pile-ups can be represented by a single dislocation between two pinned dislocations of like sing. Calculations of anelastic wave speeds at constant unloading strain rate are then compared with experimental data. The results suggest that the residual internal stress is due to pinned loops of density 10 15 M - 2 , and the viscous drag coefficient in the shock-compressed state is on the order of 10 - 7 MPa s (approximately two orders of magnitude greater than expected under ambient conditions)

Dam Break Analysis of Embankment Dams Considering Breach Characteristics

Directory of Open Access Journals (Sweden)

Abolfazl Shamsaei

2004-05-01

Full Text Available The study of dam's break, needs the definition of various parameters such as the break cause, its type, its dimension and the duration of breach development. The precise forecast for different aspects of the breach is one of the most important factors for analyzing it in embankment dam. The characteristics of the breach and determination of their vulnerability has the most effect on the waves resulting from dam break. Investigating, about the parameters of the breach in "Silveh" earth dam have been determined using the suitable model. In Silve dam a trapezoid breach with side slope z=0.01m and the average base line b=80m was computed. The duration of the breaches development is 1.9 hour. Regarding the above results and the application of DAM Break software the consequences of the probable break of the dam was determined. The analysis of the results of water covering of the city of Piranshahr located 12km from silve dam confirms that in 3 hours the water will reach the height (level of 1425 meters.

A Stream Function Theory Based Calculation of Wave Kinematics for Very Steep Waves Using a Novel Non-linear Stretching Technique

DEFF Research Database (Denmark)

Stroescu, Ionut Emanuel; Sørensen, Lasse; Frigaard, Peter Bak

2016-01-01

A non-linear stretching method was implemented for stream function theory to solve wave kinematics for physical conditions close to breaking waves in shallow waters, with wave heights limited by the water depth. The non-linear stretching method proves itself robust, efficient and fast, showing good...

Internal wave mode resonant triads in an arbitrarly stratified finite-depth ocean with background rotation

Science.gov (United States)

Varma, Dheeraj; Mathur, Manikandan

2017-11-01

Internal tides generated by barotropic tides on bottom topography or the spatially compact near-inertial mixed layer currents excited by surface winds can be conveniently represented in the linear regime as a superposition of vertical modes at a given frequency in an arbitrarily stratified ocean of finite depth. Considering modes (m , n) at a frequency ω in the primary wave field, we derive the weakly nonlinear solution, which contains a secondary wave at 2 ω that diverges when it forms a resonant triad with the primary waves. In nonuniform stratifications, resonant triads are shown to occur when the horizontal component of the classical RTI criterion k->1 +k->2 +k->3 = 0 is satisfied along with a non-orthogonality criterion. In nonuniform stratifications with a pycnocline, infinitely more pairs of primary wave modes (m , n) result in RTI when compared to a uniform stratification. Further, two nearby high modes at around the near-inertial frequency often form a resonant triad with a low mode at 2 ω , reminiscent of the features of PSI near the critical latitude. The theoretical framework is then adapted to investigate RTI in two different scenarios: low-mode internal tide scattering over topography, and internal wave beams incident on a pycnocline. The authors thank the Ministry of Earth Sciences, Government of India for financial support under the Monsoon Mission Grant MM/2014/IND-002.

Detection of a Surface-Breaking Crack by Using the Surface Wave of a Laser Ultrasound

International Nuclear Information System (INIS)

Park, Seung-Kyu; Baik, Sung-Hoon; Jung, Hyun-Kyu; Joo, Young-Sang; Cha, Hyung-Ki; Kang, Young-June

2006-01-01

A laser ultrasonic system is a non-contact inspection device with a high spatial resolution and a wide-band spectrum. Also it provides absolute measurements of the moving distance and can be applied to the hard-to access locations with curved or rough surfaces like a nuclear power plant. Several laser ultrasonic techniques are applied for the detection of micro cracks in a nuclear power plant. Also, laser ultrasonic techniques are used to measure the grain size of materials and to detect cracks in railroads and aircrafts. Though the laser ultrasonic inspection system is widely applicable, it is comparatively expensive and it provides a low signal-to-noise ratio when compared to the conventional piezoelectric transducers. Many studies have been carried out to improve the system performance. One of the widely used measurement devices of a ultrasound is the Confocal Fabry-Perot Interferometer(CFPI) with a dynamic stabilizer. The dynamic stabilizer improves the stability of the CFPI by adaptively maintaining the optimum working status at the measuring time of the CFPI. In this paper, we have investigated the detection methods of the depth of a surface-breaking crack by using the surface wave of a laser ultrasound. We have fabricated a laser ultrasonic inspection system on an optical table by using a pulse laser, a CFPI with a dynamic stabilizer and a computer. The computer acquires the laser ultrasound by using a high speed A/D converter with a sampling rate of 1000 MHz. The dynamic stabilizer stabilizes the CFPI by adaptively maintaining it at an optimum status when the laser ultrasound is generated. The computer processes the ultrasonic signal in real time to extract the depth information of a surface-breaking crack. We extracted the depth information from the peak-to-valley values in the time domain and also from the center frequencies of the spectrum in the frequency domain

Internal-wave reflection from uniform slopes: higher harmonics and Coriolis effects

Directory of Open Access Journals (Sweden)

T. Gerkema

2006-01-01

Full Text Available Weakly nonlinear reflection of internal waves from uniform slopes produces higher harmonics and mean fields; the expressions are here derived for constant stratification and with Coriolis effects fully included, i.e. the horizontal component of the earth rotation vector (referred to as 'non-traditional'' is taken into account. Uniformity in one of the horizontal directions is assumed. It is shown that solutions can be as readily derived with as without ; hence there is no need to make the so-called Traditional Approximation. Examples of reflecting internal-wave beams are presented for super-inertial, inertial and sub-inertial frequencies. The problem of resonant and non-resonant forcing of the second harmonic is studied for single plane waves; unlike under the Traditional Approximation, the problem of reflection from a horizontal bottom no longer forms a singular case. Non-traditional effects are favourable to resonant forcing at near-tidal rather than near-inertial frequencies, and generally increase the intensity of the second harmonic. Strong stratification tends to suppress non-traditional effects, but a near-total suppression is only attained for high values of stratification that are characteristic of the seasonal thermocline; in most parts of the ocean, non-traditional effects can therefore be expected to be important.

U(1) mediation of flux supersymmetry breaking

Science.gov (United States)

Grimm, Thomas W.; Klemm, Albrecht

2008-10-01

We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with Script N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kähler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.

U(1) mediation of flux supersymmetry breaking

International Nuclear Information System (INIS)

Grimm, Thomas W.; Klemm, Albrecht

2008-01-01

We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kaehler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.

Effect of Short-Crestedness and Obliquity on Non-Breaking and Breaking Wave Forces Applied to Vertical Caisson Breakwaters

DEFF Research Database (Denmark)

Martinelli, Luca; Lamberti, Alberto; Frigaard, Peter

2007-01-01

This paper addresses wave forces applied to vertical caisson breakwaters. Design diagrams are proposed to evaluate the reduction of the breaker wave force with increasing horizontal length of the units. A model in 1:100 scale of a typical Italian vertical breakwater was tested under multidirectio......This paper addresses wave forces applied to vertical caisson breakwaters. Design diagrams are proposed to evaluate the reduction of the breaker wave force with increasing horizontal length of the units. A model in 1:100 scale of a typical Italian vertical breakwater was tested under...

Wave turbulence

Energy Technology Data Exchange (ETDEWEB)

Nazarenko, Sergey [Warwick Univ., Coventry (United Kingdom). Mathematics Inst.

2011-07-01

Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as ''frozen'' turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field. (orig.)

New exact solutions of the (2 + 1)-dimensional breaking soliton system via an extended mapping method

International Nuclear Information System (INIS)

Ma Songhua; Fang Jianping; Zheng Chunlong

2009-01-01

By means of an extended mapping method and a variable separation method, a series of solitary wave solutions, periodic wave solutions and variable separation solutions to the (2 + 1)-dimensional breaking soliton system is derived.

Internal Waves and Wave Attractors in Enceladus' Subsurface Ocean

Science.gov (United States)

van Oers, A. M.; Maas, L. R.; Vermeersen, B. L. A.

2016-12-01

One of the most peculiar features on Saturn moon Enceladus is its so-called tiger stripe pattern at the geologically active South Polar Terrain (SPT), as first observed in detail by the Cassini spacecraft early 2005. It is generally assumed that the four almost parallel surface lines that constitute this pattern are faults in the icy surface overlying a confined salty water reservoir. In 2013, we formulated the original idea [Vermeersen et al., AGU Fall Meeting 2013, abstract #P53B-1848] that the tiger stripe pattern is formed and maintained by induced, tidally and rotationally driven, wave-attractor motions in the ocean underneath the icy surface of the tiger-stripe region. Such wave-attractor motions are observed in water tank experiments in laboratories on Earth and in numerical experiments [Maas et al., Nature, 338, 557-561, 1997; Drijfhout and Maas, J. Phys. Oceanogr., 37, 2740-2763, 2007; Hazewinkel et al., Phys. Fluids, 22, 107102, 2010]. Numerical simulations show the persistence of wave attractors for a range of ocean shapes and stratifications. The intensification of the wave field near the location of the surface reflections of wave attractors has been numerically and experimentally confirmed. We measured the forces a wave attractor exerts on a solid surface, near a reflection point. These reflection points would correspond to the location of the tiger stripes. Combining experiments and numerical simulations we conclude that (1) wave attractors can exist in Enceladus' subsurface sea, (2) their shape can be matched to the tiger stripes, (3) the wave attractors cause a localized force at the water-ice boundaries, (4) this force could have been large enough to contribute to fracturing the ice and (5) the wave attractors localize energy (and particles) and cause dissipation along its path, helping explain Enceladus' enigmatic heat output at the tiger stripes.

Spontaneous Wave Generation from Submesoscale Fronts and Filaments

Science.gov (United States)

Shakespeare, C. J.; Hogg, A.

2016-02-01

Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

Thin film characterization by resonantly excited internal standing waves

Energy Technology Data Exchange (ETDEWEB)

Di Fonzio, S [SINCROTRONE TRIESTE, Trieste (Italy)

1996-09-01

This contribution describes how a standing wave excited in a thin film can be used for the characterization of the properties of the film. By means of grazing incidence X-ray reflectometry one can deduce the total film thickness. On the other hand in making use of a strong resonance effect in the electric field intensity distribution inside a thin film on a bulk substrate one can learn more about the internal structure of the film. The profile of the internal standing wave is proven by diffraction experiments. The most appropriate non-destructive technique for the subsequent thin film characterization is angularly dependent X-ray fluorescence analysis. The existence of the resonance makes it a powerful tool for the detection of impurities and of ultra-thin maker layers, for which the position can be determined with very high precision (about 1% of the total film thickness). This latter aspect will be discussed here on samples which had a thin Ti marker layer at different positions in a carbon film. Due to the resonance enhancement it was still possible to perform these experiments with a standard laboratory x-ray tube and with standard laboratory tool for marker or impurity detection in thin films.

Second harmonic electromagnetic emission via Langmuir wave coalescence

International Nuclear Information System (INIS)

Willes, A.J.; Robinson, P.A.; Melrose, D.B.

1996-01-01

The coalescence of Langmuir waves to produce electromagnetic waves at twice the plasma frequency is considered. A simplified expression for the rate of production of second harmonic electromagnetic waves is obtained for a broad class of Langmuir spectra. In addition, two different analytic approximations are considered. The validity of the commonly used head-on approximation is explored, in which the two coalescing Langmuir waves are assumed to approach from opposite directions. This approximation breaks down at low Langmuir wavenumbers, and for narrow Langmuir wave spectra. A second, more general, approximation is introduced, called the narrow-spectrum approximation, which requires narrow spectral widths of the Langmuir spectra. The advantages of this approximation are that it does not break down at low Langmuir wavenumbers, and that it remains valid for relatively broad Langmuir wave spectra. Finally, the applicability of these approximations in treating harmonic radiation in type III solar radio bursts is discussed. copyright 1996 American Institute of Physics

Initial-value problem for the Gardner equation applied to nonlinear internal waves

Science.gov (United States)

Rouvinskaya, Ekaterina; Kurkina, Oxana; Kurkin, Andrey; Talipova, Tatiana; Pelinovsky, Efim

2017-04-01

The Gardner equation is a fundamental mathematical model for the description of weakly nonlinear weakly dispersive internal waves, when cubic nonlinearity cannot be neglected. Within this model coefficients of quadratic and cubic nonlinearity can both be positive as well as negative, depending on background conditions of the medium, where waves propagate (sea water density stratification, shear flow profile) [Rouvinskaya et al., 2014, Kurkina et al., 2011, 2015]. For the investigation of weakly dispersive behavior in the framework of nondimensional Gardner equation with fixed (positive) sign of quadratic nonlinearity and positive or negative cubic nonlinearity {eq1} partial η/partial t+6η( {1± η} )partial η/partial x+partial ^3η/partial x^3=0, } the series of numerical experiments of initial-value problem was carried out for evolution of a bell-shaped impulse of negative polarity (opposite to the sign of quadratic nonlinear coefficient): {eq2} η(x,t=0)=-asech2 ( {x/x0 } ), for which amplitude a and width x0 was varied. Similar initial-value problem was considered in the paper [Trillo et al., 2016] for the Korteweg - de Vries equation. For the Gardner equation with different signs of cubic nonlinearity the initial-value problem for piece-wise constant initial condition was considered in detail in [Grimshaw et al., 2002, 2010]. It is widely known, for example, [Pelinovsky et al., 2007], that the Gardner equation (1) with negative cubic nonlinearity has a family of classic solitary wave solutions with only positive polarity,and with limiting amplitude equal to 1. Therefore evolution of impulses (2) of negative polarity (whose amplitudes a were varied from 0.1 to 3, and widths at the level of a/2 were equal to triple width of solitons with the same amplitude for a 1) was going on a universal scenario with the generation of nonlinear Airy wave. For the Gardner equation (1) with the positive cubic nonlinearity coefficient there exist two one-parametric families of

The International Pulsar Timing Array project: using pulsars as a gravitational wave detector

Energy Technology Data Exchange (ETDEWEB)

Hobbs, G; Burke-Spolaor, S; Champion, D [Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710 (Australia); Archibald, A [Department of Physics, McGill University, Montreal, PQ, H3A 2T8 (Canada); Arzoumanian, Z [CRESST/USRA, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Backer, D [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States); Bailes, M; Bhat, N D R [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn VIC 3122 (Australia); Burgay, M [Universita di Cagliari, Dipartimento di Fisica, SP Monserrato-Sestu km 0.7, 09042 Monserrato (Canada) (Italy); Cognard, I; Desvignes, G; Ferdman, R D [Station de Radioastronomie de Nanay, Observatoire de Paris, 18330 Nancay (France); Coles, W [Electrical and Computer Engineering, University of California at San Diego, La Jolla, CA (United States); Cordes, J [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Demorest, P [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Finn, L [Center for Gravitational Wave Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Freire, P [Max-Planck-Institut fuer Radioastronomie, Auf Dem Huegel 69, 53121, Bonn (Germany); Gonzalez, M [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Hessels, J [Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam (Netherlands); Hotan, A, E-mail: george.hobbs@csiro.a [Department of Imaging and Applied Physics, Curtin University, Bentley, WA (Australia)

2010-04-21

The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim of detecting ultra-low frequency (approx 10{sup -9}-10{sup -8} Hz) gravitational waves. Here we introduce the project, review the methods used to search for gravitational waves emitted from coalescing supermassive binary black-hole systems in the centres of merging galaxies and discuss the status of the project.

Horizontal circulation and jumps in Hamiltonian wave models

NARCIS (Netherlands)

Gagarina, Elena; van der Vegt, Jacobus J.W.; Bokhove, Onno

2013-01-01

We are interested in the numerical modeling of wave-current interactions around surf zones at beaches. Any model that aims to predict the onset of wave breaking at the breaker line needs to capture both the nonlinearity of the wave and its dispersion. We have therefore formulated the Hamiltonian

Surfing surface gravity waves

Science.gov (United States)

Pizzo, Nick

2017-11-01

A simple criterion for water particles to surf an underlying surface gravity wave is presented. It is found that particles travelling near the phase speed of the wave, in a geometrically confined region on the forward face of the crest, increase in speed. The criterion is derived using the equation of John (Commun. Pure Appl. Maths, vol. 6, 1953, pp. 497-503) for the motion of a zero-stress free surface under the action of gravity. As an example, a breaking water wave is theoretically and numerically examined. Implications for upper-ocean processes, for both shallow- and deep-water waves, are discussed.

Atmospheric gravity waves observed by an international network of micro-barographs

International Nuclear Information System (INIS)

Marty, Julien

2010-01-01

The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) manages an international network of forty-two operational infra-sound stations recording the pressure fluctuations produced at the ground surface by infrasonic waves. This thesis demonstrates that most of these stations also accurately detect the pressure fluctuations in the entire gravity wave band. This work includes carrying out and analyzing several metrological laboratory experiments and a field campaign (M2008) in Mongolia in 2008. The layout of the experiments as well as the interpretation of their results gave rise to the development of a new linear spectral numerical model able to simulate the generation and propagation of gravity waves. This model was used to quantify the gravity waves produced by the atmospheric cooling that occurs during solar eclipses. The pressure fluctuations expected at ground level were estimated and compared to the data recorded during the 1 August 2008 solar eclipse by the CTBTO and M2008 stations. A detailed data analysis reveals two waves with similar time-frequency characteristics to those simulated for a stratospheric and tropospheric cooling. This constitutes, to our knowledge, a unique result. The validation of worldwide and pluri-annual pressure measurements in the entire gravity wave band allowed the statistical study of gravity wave spectra and atmospheric tides. The work presented throughout this thesis has led to the publication of two articles. A third one is in the drafting process. (author)

Improving the analysis of biogeochemical patterns associated with internal waves in the strait of Gibraltar using remote sensing images

Science.gov (United States)

Navarro, Gabriel; Vicent, Jorge; Caballero, Isabel; Gómez-Enri, Jesús; Morris, Edward P.; Sabater, Neus; Macías, Diego; Bolado-Penagos, Marina; Gomiz, Juan Jesús; Bruno, Miguel; Caldeira, Rui; Vázquez, Águeda

2018-05-01

High Amplitude Internal Waves (HAIWs) are physical processes observed in the Strait of Gibraltar (the narrow channel between the Atlantic Ocean and the Mediterranean Sea). These internal waves are generated over the Camarinal Sill (western side of the strait) during the tidal outflow (toward the Atlantic Ocean) when critical hydraulic conditions are established. HAIWs remain over the sill for up to 4 h until the outflow slackens, being then released (mostly) towards the Mediterranean Sea. These have been previously observed using Synthetic Aperture Radar (SAR), which captures variations in surface water roughness. However, in this work we use high resolution optical remote sensing, with the aim of examining the influence of HAIWs on biogeochemical processes. We used hyperspectral images from the Hyperspectral Imager for the Coastal Ocean (HICO) and high spatial resolution (10 m) images from the MultiSpectral Instrument (MSI) onboard the Sentinel-2A satellite. This work represents the first attempt to examine the relation between internal wave generation and the water constituents of the Camarinal Sill using hyperspectral and high spatial resolution remote sensing images. This enhanced spatial and spectral resolution revealed the detailed biogeochemical patterns associated with the internal waves and suggests local enhancements of productivity associated with internal waves trains.

Topographically induced internal solitary waves in a pycnocline: Ultrasonic probes and stereo-correlation measurements

International Nuclear Information System (INIS)

Dossmann, Yvan; Paci, Alexandre; Auclair, Francis; Lepilliez, Mathieu; Cid, Emmanuel

2014-01-01

Internal solitary waves (ISWs) are large amplitude stable waves propagating in regions of high density gradients such as the ocean pycnocline. Their dynamics has often been investigated in two-dimensional approaches, however, their three-dimensional evolution is still poorly known. Experiments have been conducted in the large stratified water tank of CNRM-GAME to study the generation of ISWs in two academic configurations inspired by oceanic regimes. First, ultrasonic probes are used to measure the interfacial displacement in the two configurations. In the primary generation case for which the two layers are of constant density, the generation of ISWs is investigated in two series of experiments with varying amplitude and forcing frequency. In the secondary generation case for which the lower layer is stratified, the generation of ISWs from the impact of an internal wave beam on the pycnocline and their subsequent dynamics is studied. The dynamics of ISWs in these two regimes accords well with analytical approaches and numerical simulations performed in analogous configurations. Then, recent developments of a stereo correlation technique are used to describe the three-dimensional structure of propagating ISWs. In the primary generation configuration, small transverse effects are observed in the course of the ISW propagation. In the secondary generation configuration, larger transverse structures are observed in the interfacial waves dynamics. The interaction between interfacial troughs and internal waves propagating in the lower stratified layer are a possible cause for the generation of these structures. The magnitude of these transverse structures is quantified with a nondimensional parameter in the two configurations. They are twice as large in the secondary generation case as in the primary generation case

The numerical simulation of the WWER-440/V-213 reactor pressure vessel internals response to maximum hypothetical large break loss of coolant accident

International Nuclear Information System (INIS)

Hermansky, P.; Krajcovic, M.

2012-01-01

The reactor internals are designed to ensure cooling of the fuel, to ensure the movement of emergency control assemblies under all operating conditions including accidents and facilitate removal of the fuel and of the internals following an accident This paper presents results of the numerical simulation of the WWER-440/V213 reactor vessel internals dynamic response to maximum hypothetical Large-Break Loss of Coolant Accident. The purpose of this analysis is to determine the reactor vessel internals response due to rapid depressurization and to prove no such deformations occur in the reactor vessel internals which would prevent timely and proper activation of the emergency control assemblies. (Authors)

Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion.

Science.gov (United States)

Morichetti, Francesco; Canciamilla, Antonio; Ferrari, Carlo; Samarelli, Antonio; Sorel, Marc; Melloni, Andrea

2011-01-01

Wave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s(-1).

Internal inspection of reinforced concrete for nuclear structures using shear wave tomography

International Nuclear Information System (INIS)

Scott, David B.

2013-01-01

Highlights: • Aging of reinforced concrete used for worldwide nuclear structures is increasing and necessitating evaluation. • Nondestructive evaluation is a tool for assessing the condition of reinforced concrete of nuclear structures. • Ultrasonic shear wave tomography as a stress wave technique has begun to be utilized for investigation of concrete material. • A study using ultrasonic shear wave tomography indicates anomalies vital to the long-term operation of the structure. • The use of this technique has shown to successfully evaluate the internal state of reinforced concrete members. - Abstract: Reinforced concrete is important for nuclear related structures. Therefore, the integrity of structural members consisting of reinforced concrete is germane to the safe operation and longevity of these facilities. Many issues that reduce the likelihood of safe operation and longevity are not visible on the surface of reinforced concrete material. Therefore, an investigation of reinforced concrete material should include techniques which will allow peering into the concrete member and determining its internal state. The performance of nondestructive evaluations is pursuant to this goal. Some of the categories of nondestructive evaluations are electrochemical, magnetism, ground penetrating radar, and ultrasonic testing. A specific ultrasonic testing technique, namely ultrasonic shear wave tomography, is used to determine presence and extent of voids, honeycombs, cracks perpendicular to the surface, and/or delamination. This technique, and others similar to it, has been utilized in the nuclear industry to determine structural conditions

Computational and experimental study of the effect of mass transfer on liquid jet break-up

Science.gov (United States)

Schetz, J. A.; Situ, M.

1983-06-01

A computational method has been developed to predict the effect of mass transfer on liquid jet break-up in coaxial, low velocity gas streams. Two conditions, both with and without the effect of mass transfer on the jet break-up, are calculated, and compared with experimental results and the classical linear theory. Methanol and water were used as the injectants. The numerical solution can predict the instantaneous shape of the jet surface and the break-up time, and it is very close to the experimental results. The numerical solutions and the experimental results both indicate that the wave number of the maximum instability is about 6.9, higher than 4.51 which was predicted by Rayleigh's linear theory. The experimental results and numerical solution show that the growth of the amplitude of the trough is faster than the growth of the amplitude of the crest, especially for a rapidly vaporizing jet. The numerical solutions show that for the small rates of evaporation, the effect of the mass transfer on the interface has a stabilizing effect near the wave number for maximum instability. Inversely, it has a destabilizing effect far from the wave number for maximum instability. For rapid evaporation, the effect of the mass transfer always has a destabilizing effect and decreases the break-up time of the jet.

Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment

Directory of Open Access Journals (Sweden)

O. D. Shishkina

2013-10-01

Full Text Available An interaction of internal solitary waves with the shelf edge in the time periods related to the presence of a pronounced seasonal pycnocline in the Red Sea and in the Alboran Sea is analysed via satellite photos and SAR images. Laboratory data on transformation of a solitary wave of depression while passing along the transverse bottom step were obtained in a tank with a two-layer stratified fluid. The certain difference between two characteristic types of hydrophysical phenomena was revealed both in the field observations and in experiments. The hydrological conditions for these two processes were named the "deep" and the "shallow" shelf respectively. The first one provides the generation of the secondary periodic short internal waves – "runaway" edge waves – due to change in the polarity of a part of a soliton approaching the shelf normally. Another one causes a periodic shear flow in the upper quasi-homogeneous water layer with the period of incident solitary wave. The strength of the revealed mechanisms depends on the thickness of the water layer between the pycnocline and the shelf bottom as well as on the amplitude of the incident solitary wave.

Risk analysis of breakwater caisson under wave attack using load surface approximation

Science.gov (United States)

Kim, Dong Hyawn

2014-12-01

A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method (FORM) can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.

Detecting Lorentz Violations with Gravitational Waves From Black Hole Binaries

Science.gov (United States)

Sotiriou, Thomas P.

2018-01-01

Gravitational wave observations have been used to test Lorentz symmetry by looking for dispersive effects that are caused by higher order corrections to the dispersion relation. In this Letter I argue on general grounds that, when such corrections are present, there will also be a scalar excitation. Hence, a smoking-gun observation of Lorentz symmetry breaking would be the direct detection of scalar waves that travel at a speed other than the speed of the standard gravitational wave polarizations or the speed of light. Interestingly, in known Lorentz-breaking gravity theories the difference between the speeds of scalar and tensor waves is virtually unconstrained, whereas the difference between the latter and the speed of light is already severely constrained by the coincident detection of gravitational waves and gamma rays from a binary neutron star merger.

The Offlap Break Position Vs Sea Level: A Discussion

Science.gov (United States)

Tropeano, M.; Pieri, P.; Pomar, L.; Sabato, L.

Sedimentary lithosomes with subhorizontal topsets, basinward prograding foresets and subhorizontal bottomsets are common in the geologic record, and most of them display similar bedding architectures and/or seismic reflection patterns (i.e. Gylbert- type deltas and shelf wedges). Nevertheless, in shallow marine settings these bodies may form in distinct sedimentary environments and they result from different sed- imentary processes. The offlap break (topset edge) occurs in relation to the posi- tion of baselevel and two main groups of lithosomes can be differentiated with re- spect to the position of the offlap break within the shelf profile. The baselevel of the first group is the sea level (or lake level); the topsets are mainly composed by continental- or very-shallow-water sedimentary facies and the offlap break practi- cally corresponds to the shoreline. Exemples of these lithosomes are high-constructive deltas (river-dominated deltas) and prograding beaches. For the second group, base- level corresponds to the base of wave/tide traction, and their topsets are mostly composed by shoreface/nearshore deposits. Examples of these lithosomes are high- destructive deltas (wave/tide-dominated deltas) and infralittoral prograding wedges (i.e Hernandez-Molina et al., 2000). The offlap break corresponds to the shelf edge (shoreface edge), which is located at the transition between nearshore and offshore set- tings, where a terrace prodelta- or transition-slope may develop (Pomar &Tropeano, 2001). Two main problems derive from these alternative interpretations of shallow- marine seaward prograding lithosomes: 1) both in ancient sedimentary shallow-marine successios (showing seaward prograding foresets) and in high resolution seismic pro- files (showing shelf wedges), the offlap break is commonly considered to correspond to the sea-level (shoreline) and used to inferr paleo sea-level positions and to construct sea-level curves. Without a good facies control, this use of

Vertical Wave Impacts on Offshore Wind Turbine Inspection Platforms

DEFF Research Database (Denmark)

Bredmose, Henrik; Jacobsen, Niels Gjøl

2011-01-01

Breaking wave impacts on a monopile at 20 m depth are computed with a VOF (Volume Of Fluid) method. The impacting waves are generated by the second-order focused wave group technique, to obtain waves that break at the position of the monopile. The subsequent impact from the vertical run-up flow...... on a horizontal inspection platform is computed for five different platform levels. The computational results show details of monopile impact such as slamming pressures from the overturning wave front and the formation of run-up flow. The results show that vertical platform impacts can occur at 20 m water depth....... The dependence of the vertical platform load to the platform level is discussed. Attention is given to the significant downward force that occur after the upward force associated with the vertical impact. The effect of the numerical resolution on the results is assessed. The position of wave overturning is found...

Gauge unification, non-local breaking, open strings

International Nuclear Information System (INIS)

Trapletti, M.

2005-01-01

The issue of non-local GUT symmetry breaking is addressed in the context of open string model building. We study Z N xZ M ' orbifolds with all the GUT-breaking orbifold elements acting freely, as rotations accompanied by translations in the internal space. We consider open strings quantized on these backgrounds, distinguishing whether the translational action is parallel or perpendicular to the D-branes. GUT breaking is impossible in the purely perpendicular case, non-local GUT breaking is instead allowed in the purely parallel case. In the latter, the scale of breaking is set by the compactification moduli, and there are no fixed points with reduced gauge symmetry, where dangerous explicit GUT-breaking terms could be located. We investigate the mixed parallel+perpendicular case in a Z 2 xZ 2 ' example, having also a simplified field theory realization. It is a new S 1 /Z 2 xZ 2 ' orbifold-GUT model, with bulk gauge symmetry SU(5)xSU(5) broken locally to the Standard Model gauge group. In spite of the locality of the GUT symmetry breaking, there is no localized contribution to the running of the coupling constants, and the unification scale is completely set by the length of S 1

Near-inertial waves and deep ocean mixing

Science.gov (United States)

Shrira, V. I.; Townsend, W. A.

2013-07-01

For the existing pattern of global oceanic circulation to exist, there should be sufficiently strong turbulent mixing in the abyssal ocean, the mechanisms of which are not well understood as yet. The review discusses a plausible mechanism of deep ocean mixing caused by near-inertial waves in the abyssal ocean. It is well known how winds in the atmosphere generate near-inertial waves in the upper ocean, which then propagate downwards losing their energy in the process; only a fraction of the energy at the surface reaches the abyssal ocean. An open question is whether and, if yes, how these weakened inertial motions could cause mixing in the deep. We review the progress in the mathematical description of a mechanism that results in an intense breaking of near-inertial waves near the bottom of the ocean and thus enhances the mixing. We give an overview of the present state of understanding of the problem covering both the published and the unpublished results; we also outline the key open questions. For typical ocean stratification, the account of the horizontal component of the Earth's rotation leads to the existence of near-bottom wide waveguides for near-inertial waves. Due to the β-effect these waveguides are narrowing in the poleward direction. Near-inertial waves propagating poleward get trapped in the waveguides; we describe how in the process these waves are focusing more and more in the vertical direction, while simultaneously their group velocity tends to zero and wave-induced vertical shear significantly increases. This causes the development of shear instability, which is interpreted as wave breaking. Remarkably, this mechanism of local intensification of turbulent mixing in the abyssal ocean can be adequately described within the framework of linear theory. The qualitative picture is similar to wind wave breaking on a beach: the abyssal ocean always acts as a surf zone for near-inertial waves.

Near-inertial waves and deep ocean mixing

International Nuclear Information System (INIS)

Shrira, V I; Townsend, W A

2013-01-01

For the existing pattern of global oceanic circulation to exist, there should be sufficiently strong turbulent mixing in the abyssal ocean, the mechanisms of which are not well understood as yet. The review discusses a plausible mechanism of deep ocean mixing caused by near-inertial waves in the abyssal ocean. It is well known how winds in the atmosphere generate near-inertial waves in the upper ocean, which then propagate downwards losing their energy in the process; only a fraction of the energy at the surface reaches the abyssal ocean. An open question is whether and, if yes, how these weakened inertial motions could cause mixing in the deep. We review the progress in the mathematical description of a mechanism that results in an intense breaking of near-inertial waves near the bottom of the ocean and thus enhances the mixing. We give an overview of the present state of understanding of the problem covering both the published and the unpublished results; we also outline the key open questions. For typical ocean stratification, the account of the horizontal component of the Earth's rotation leads to the existence of near-bottom wide waveguides for near-inertial waves. Due to the β-effect these waveguides are narrowing in the poleward direction. Near-inertial waves propagating poleward get trapped in the waveguides; we describe how in the process these waves are focusing more and more in the vertical direction, while simultaneously their group velocity tends to zero and wave-induced vertical shear significantly increases. This causes the development of shear instability, which is interpreted as wave breaking. Remarkably, this mechanism of local intensification of turbulent mixing in the abyssal ocean can be adequately described within the framework of linear theory. The qualitative picture is similar to wind wave breaking on a beach: the abyssal ocean always acts as a surf zone for near-inertial waves. (paper)

On generation and evolution of seaward propagating internal solitary waves in the northwestern South China Sea

Science.gov (United States)

Xu, Jiexin; Chen, Zhiwu; Xie, Jieshuo; Cai, Shuqun

2016-03-01

In this paper, the generation and evolution of seaward propagating internal solitary waves (ISWs) detected by satellite image in the northwestern South China Sea (SCS) are investigated by a fully nonlinear, non-hydrostatic, three-dimensional Massachusetts Institute of Technology general circulation model (MITgcm). The three-dimensional (3D) modeled ISWs agree favorably with those by satellite image, indicating that the observed seaward propagating ISWs may be generated by the interaction of barotropic tidal flow with the arc-like continental slope south of Hainan Island. Though the tidal current is basically in east-west direction, different types of internal waves are generated by tidal currents flowing over the slopes with different shaped shorelines. Over the slope where the shoreline is straight, only weak internal tides are generated; over the slope where the shoreline is seaward concave, large-amplitude internal bores are generated, and since the concave isobaths of the arc-like continental slope tend to focus the baroclinic tidal energy which is conveyed to the internal bores, the internal bores can efficiently disintegrate into a train of rank-ordered ISWs during their propagation away from the slope; while over the slope where the shoreline is seaward convex, no distinct internal tides are generated. It is also implied that the internal waves over the slope are generated due to mixed lee wave mechanism. Furthermore, the effects of 3D model, continental slope curvature, stratification, rotation and tidal forcing on the generation of ISWs are discussed, respectively. It is shown that, the amplitude and phase speed of ISWs derived from a two-dimensional (2D) model are smaller than those from the 3D one, and the 3D model has an advantage over 2D one in simulating the ISWs generated by the interaction between tidal currents and 3D curved continental slope; the reduced continental slope curvature hinders the extension of ISW crestline; both weaker stratification

Fiber break location technique utilizing stimulated Brillouin scattering effects in optical fiber

International Nuclear Information System (INIS)

Bakar, A A A; Al-Mansoori, M H; Mahdi, M A; Mohd Azau, M A; Zainal Abidin, M S

2009-01-01

A new technique of fiber break detection system in optical communication networks is proposed and experimentally demonstrated in this paper. This technique is based-on continuous wave light source rather than pulsed source that is commonly deployed in existing techniques. The nonlinear effect of stimulated Brillouin scattering is manipulated to locate the fiber-break position in optical communication networks. This technique enables the utilization of a less-sensitive photodetector to detect the Brillouin Stokes line since its intensity increases with the fiber length in the detectable region. The fiber break location can be determined with accuracy of more than 98% for fiber length less than 50 km using this technique

The internal waves and Rayleigh-Taylor instability in compressible quantum plasmas

International Nuclear Information System (INIS)

Lu, H. L.; Qiu, X. M.

2011-01-01

In this paper, we investigate the quantum effect on internal waves and Rayleigh-Taylor (RT) instability in compressible quantum plasmas. First of all, let us consider the case of the limit of short wavelength perturbations. In the case, the dispersion relation including quantum and compressibility effects and the RT instability growth rate can be derived using Wentzel-Kramers-Brillouin method. The results show that the internal waves can propagate along the transverse direction due to the quantum effect, which was first pointed out by Bychkov et al.[Phys. Lett. A 372, 3042 (2008)], and the coupling between it and compressibility effect, which is found out in this paper. Then, without making the approximation assumption of short wavelength limit, we examine the linearized perturbation equation following Qiu et al.'s solving process [Phys. Plasmas 10, 2956 (2003)]. It is found that the quantum effect always stabilizes the RT instability in either incompressible or compressible quantum plasmas. Moreover, in the latter case, the coupling between it and compressibility effect makes this stabilization further enhance.

Nonlinear self-modulation of ion-acoustic waves

International Nuclear Information System (INIS)

Ikezi, H.; Schwarzenegger, K.; Simons, A.L.; Ohsawa, Y.; Kamimura, T.

1978-01-01

The nonlinear evolution of an ion-acoustic wave packet is studied. Experimentally, it is found that (i) nonlinear phase modulation develops in the wave packet; (ii) the phase modulation, together with the dispersion effect, causes expansion and breaking of the wave packet; (iii) the ions trapped in the troughs of the wave potential introduce self-phase modulation; and (iv) the ion-acoustic wave is stable with respect to the modulational instability. Computer simulations have reproduced the experimental results. The physical picture and the model equation describing the wave evolution are discussed

Experimental study of the propgation and dispersion of internal atmospheric gravity waves

International Nuclear Information System (INIS)

Ballard, K.A.

1981-01-01

Traveling ionospheric disturbances (TID's) appear as large-scale transverse waves in the F-region (150 to 1000 km altitude), with frequencies on the order of 0.005 to 0.005 cycles per minute, which propagate horizontally over hundreds or even thousands of kilometers. These disturbances have been observed by various radiowave techniques over the past thirty-five years and are now generally accepted as being the manifestation, in the ionized medium, of internal atmospheric gravity waves. A model describing the propagation of gravity waves in an isothermal atmosphere is presented here. The dispersion relation is derived from fundamental principles, and the relation between phase velocity and group velocity is examined. The effects of the Coriolis force and horizontally stratified winds on wave propagation are also analyzed. Conservation of energy in the gravity wave requires increasing amplitude with increasing altitude, inasmuch as the atmospheric density decreases with height. However, this is counteracted by dissipation of wave energy by ion drag, thermal conductivity, and viscous damping. The production of TID's (in the ionized medium) by gravity waves (in the neutral medium) is discussed in quantitative terms, and the vertical predictive function is derived. Dartmouth College has operated a three-station ionosonde network in northern New Hampshire and Vermont on an intermittent basis since 1968. Seven large TID's, found in the 1969 data, are reexamined here in an exhaustive and successful comparison with the gravity wave model. Iso-true-height contours of electron density are used to determine several pertinent TID wave parameters as a function of height

Limitations On The Creation of Continuously Surfable Waves Generated By A Pressure Source Moving In A Circular Path

NARCIS (Netherlands)

Schmied, S.A.

2014-01-01

The aim of the research presented in this work was to investigate the novel idea to produce continuous breaking waves, whereby a pressure source was rotated within an annular wave pool. The concept was that the pressure source generates non-breaking waves that propagate inward to the inner ring of

Modeling storm waves

International Nuclear Information System (INIS)

Benoit, M.; Marcos, F.; Teisson, Ch.

1999-01-01

Nuclear power stations located on the coast take the water they use to cool their circuits from the sea. The water intake and discharge devices must be able to operate in all weathers, notably during extreme storms, with waves 10 m high and over. To predict the impact of the waves on the equipment, they are modeled digitally from the moment they form in the middle of the ocean right up to the moment they break on the shore. (authors)

Generalized internal long wave equations: construction, hamiltonian structure and conservation laws

International Nuclear Information System (INIS)

Lebedev, D.R.

1982-01-01

Some aspects of the theory of the internal long-wave equations (ILW) are considered. A general class of the ILW type equations is constructed by means of the Zakharov-Shabat ''dressing'' method. Hamiltonian structure and infinite numbers of conservation laws are introduced. The considered equations are shown to be Hamiltonian in the so-called second Hamiltonian structu

Breaking the Waves: How the Phenomenon of European Jihadism Militates Against the Wave Theory of Terrorism

Directory of Open Access Journals (Sweden)

Proshyn Denys

2015-12-01

Full Text Available David Rapoport’s Wave theory of terrorism is one of the most oftencited theories in the literature on terrorist violence. Rapoport is praised for having provided researchers with a universal instrument which allows them to explain the origin and transformation of various historical types of terrorism by applying to them the concept of global waves of terrorist violence driven by universal political impulses. This article, testing the Wave theory against the recent phenomenon of homegrown jihadism in Europe, uncovers this theory’s fundamental weaknesses and questions its real academic and practical value.

Analysis of Different Methods for Wave Generation and Absorption in a CFD-Based Numerical Wave Tank

Directory of Open Access Journals (Sweden)

Adria Moreno Miquel

2018-06-01

Full Text Available In this paper, the performance of different wave generation and absorption methods in computational fluid dynamics (CFD-based numerical wave tanks (NWTs is analyzed. The open-source CFD code REEF3D is used, which solves the Reynolds-averaged Navier–Stokes (RANS equations to simulate two-phase flow problems. The water surface is computed with the level set method (LSM, and turbulence is modeled with the k-ω model. The NWT includes different methods to generate and absorb waves: the relaxation method, the Dirichlet-type method and active wave absorption. A sensitivity analysis has been conducted in order to quantify and compare the differences in terms of absorption quality between these methods. A reflection analysis based on an arbitrary number of wave gauges has been adopted to conduct the study. Tests include reflection analysis of linear, second- and fifth-order Stokes waves, solitary waves, cnoidal waves and irregular waves generated in an NWT. Wave breaking over a sloping bed and wave forces on a vertical cylinder are calculated, and the influence of the reflections on the wave breaking location and the wave forces on the cylinder is investigated. In addition, a comparison with another open-source CFD code, OpenFOAM, has been carried out based on published results. Some differences in the calculated quantities depending on the wave generation and absorption method have been observed. The active wave absorption method is seen to be more efficient for long waves, whereas the relaxation method performs better for shorter waves. The relaxation method-based numerical beach generally results in lower reflected waves in the wave tank for most of the cases simulated in this study. The comparably better performance of the relaxation method comes at the cost of larger computational requirements due to the relaxation zones that have to be included in the domain. The reflections in the NWT in REEF3D are generally lower than the published results for

Path-breaking books in regional science

NARCIS (Netherlands)

Waldorf, BS

This article presents a collection of regional science books that long-standing members of the Regional Science Association International (RSAI) identified as path-breaking books. The most frequently nominated books include the "classics" by Isard, the seminal books in urban economics by Alonso,

The international workshop on wave hindcasting and forecasting and the coastal hazards symposium

Science.gov (United States)

Breivik, Øyvind; Swail, Val; Babanin, Alexander V.; Horsburgh, Kevin

2015-05-01

Following the 13th International Workshop on Wave Hindcasting and Forecasting and 4th Coastal Hazards Symposium in October 2013 in Banff, Canada, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the history of the conference since its inception in 1986 and of the progress made in the fields of wind-generated ocean waves and the modelling of coastal hazards before we summarize the main results of the papers that have appeared in the topical collection.

Temporal coherence of the acoustic field forward propagated through a continental shelf with random internal waves.

Science.gov (United States)

Gong, Zheng; Chen, Tianrun; Ratilal, Purnima; Makris, Nicholas C

2013-11-01

An analytical model derived from normal mode theory for the accumulated effects of range-dependent multiple forward scattering is applied to estimate the temporal coherence of the acoustic field forward propagated through a continental-shelf waveguide containing random three-dimensional internal waves. The modeled coherence time scale of narrow band low-frequency acoustic field fluctuations after propagating through a continental-shelf waveguide is shown to decay with a power-law of range to the -1/2 beyond roughly 1 km, decrease with increasing internal wave energy, to be consistent with measured acoustic coherence time scales. The model should provide a useful prediction of the acoustic coherence time scale as a function of internal wave energy in continental-shelf environments. The acoustic coherence time scale is an important parameter in remote sensing applications because it determines (i) the time window within which standard coherent processing such as matched filtering may be conducted, and (ii) the number of statistically independent fluctuations in a given measurement period that determines the variance reduction possible by stationary averaging.

Hindcast of breaking waves and its impact at an island sheltered coast, Karwar

Science.gov (United States)

Dora, G. Udhaba; Kumar, V. Sanil

2018-01-01

Variability in the characteristics of depth-induced wave breakers along a non-uniform coastal topography and its impact on the morpho-sedimentary processes is examined at the island sheltered wave-dominated micro-tidal coast, Karwar, west coast of India. Waves are simulated using the coupled wind wave model, SWAN nested in WAVEWATCH III, forced by the reanalysis winds from different sources (NCEP/NCAR, ECMWF, and NCEP/CFSR). Impact of the wave breakers is evaluated through mean longshore current and sediment transport for various wave energy conditions across different coastal morphology. Study revealed that the NCEP/CFSR wind is comparatively reasonable in simulation of nearshore waves using the SWAN model nested by 2D wave spectra generated from WAVEWATCH III. The Galvin formula for estimating mean longshore current using the crest wave period and the Kamphuis approximation for longshore sediment transport is observed realistically at the sheltered coastal environment while the coast interacts with spilling and plunging breakers.

Modeling impurity-assisted chain creation in noble-metal break junctions

International Nuclear Information System (INIS)

Di Napoli, S; Thiess, A; Blügel, S; Mokrousov, Y

2012-01-01

In this work we present the generalization of the model for chain formation in break junctions, introduced by Thiess et al (2008 Nano Lett. 8 2144), to zigzag transition-metal chains with s and p impurities. We apply this extended model to study the producibility trends for noble-metal chains with impurities, often present in break junction experiments, namely, Cu, Ag and Au chains with H, C, O and N adatoms. Providing the material-specific parameters for our model from systematic full-potential linearized augmented plane-wave first-principles calculations, we find that the presence of such impurities crucially affects the binding properties of the noble-metal chains. We reveal that both the impurity-induced bond strengthening and the formation of zigzag bonds can lead to a significantly enhanced probability for chain formation in break junctions. (paper)

Multinode analysis of small breaks for B and W's 205-fuel-assembly nuclear plants with internals vent valves

International Nuclear Information System (INIS)

Jones, R.C.; Dunn, B.M.; Parks, C.E.

1976-03-01

Multinode analyses were conducted for several small breaks in the reactor coolant system of B and W's 205-fuel-assembly nuclear plants with internals vent valves. The multinode blowdown code CRAFT was used to evaluate the hydrodynamics and transient water inventories of the reactor coolant system. The FOAM code was used to compute a swell level history for the core, and the THETA1-B code was used to perform transient fuel pin thermal calculations. Curves showing the parameters of interest are presented. The results are well within the Final Acceptance Criteria

Multinode analysis of small breaks for B and W's 145-fuel-assembly nuclear plants with internals vent valves

International Nuclear Information System (INIS)

Parks, C.E.; Allen, R.J.; Cartin, L.R.

1976-03-01

Multinode analyses were conducted for several small breaks in the reactor coolant system of B and W's 145 fuel-assembly nuclear plants with internals vent valves. The multinode blowdown code CRAFT was used to evaluate the hydrodynamics and transient water inventories of the reactor coolant system. The FOAM code was used to compute a swell level history for the core, and the THETA1-B code was used to perform transient fuel pin thermal calculations. Curves showing the parameters of interest are presented. These results are well within the Final Acceptance Criteria

Lecture Notes for the Course in Water Wave Mechanics

DEFF Research Database (Denmark)

Andersen, Thomas Lykke; Frigaard, Peter

knowledge. The course is at the same time an introduction to the course in coastal hydraulics on the 8th semester. The notes cover the following five lectures: 1. Definitions. Governing equations and boundary conditions. Derivation of velocity potential for linear waves. Dispersion relationship. 2. Particle...... paths, velocities, accelerations, pressure variation, deep and shallow water waves, wave energy and group velocity. 3. Shoaling, refraction, diffraction and wave breaking. 4. Irregular waves. Time domain analysis of waves. 5. Wave spectra. Frequency domain analysis of waves. The present notes are based...

Hydrodynamic Forces from Steep Waves in Rivers

Energy Technology Data Exchange (ETDEWEB)

Loevoll, A.

1996-12-31

The reservoir behind a hydroelectric power production dam has an enormous potential for destruction in case of a dam break. The present doctoral thesis evaluates the hydrodynamic forces from steep waves in rivers. In the laboratory, forces on a structure shaped as a vertical cylinder of rectangular cross section were measured, and the threshold condition for the bed sediment was investigated. A wave parameter {alpha} is introduced to describe the gradient of a wave front. The flow condition in the flume was reproduced by a 3-D numerical model. For various values of the wave parameter the forces were measured and compared to the drag force calculated from measured depth and velocity. From these comparisons the hydrodynamic force can be calculated as drag only, even in the case of a breaking wave front. The contribution from inertia relative to drag depends on the size of the structure. For larger structures the contributions may be important in steep waves. To study the initiation of motion (of sediments) under unsteady flow, waves of various parameter values were passed over a gravel covered bed. The initiation of motion starts before the peak of the wave, and is given by Shield`s relation if the friction slope is applied. No dependence upon the wave gradient was found. A relation was established which gives the critical shear stress if the friction slope is estimated by the bottom slope. 65 refs., 41 figs., 10 tabs.

Hydrodynamic Forces from Steep Waves in Rivers

International Nuclear Information System (INIS)

Loevoll, A.

1996-01-01

The reservoir behind a hydroelectric power production dam has an enormous potential for destruction in case of a dam break. The present doctoral thesis evaluates the hydrodynamic forces from steep waves in rivers. In the laboratory, forces on a structure shaped as a vertical cylinder of rectangular cross section were measured, and the threshold condition for the bed sediment was investigated. A wave parameter α is introduced to describe the gradient of a wave front. The flow condition in the flume was reproduced by a 3-D numerical model. For various values of the wave parameter the forces were measured and compared to the drag force calculated from measured depth and velocity. From these comparisons the hydrodynamic force can be calculated as drag only, even in the case of a breaking wave front. The contribution from inertia relative to drag depends on the size of the structure. For larger structures the contributions may be important in steep waves. To study the initiation of motion (of sediments) under unsteady flow, waves of various parameter values were passed over a gravel covered bed. The initiation of motion starts before the peak of the wave, and is given by Shield's relation if the friction slope is applied. No dependence upon the wave gradient was found. A relation was established which gives the critical shear stress if the friction slope is estimated by the bottom slope. 65 refs., 41 figs., 10 tabs

Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

Science.gov (United States)

Borges, L. H. C.; Barone, F. A.

2016-02-01

Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.

Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

Energy Technology Data Exchange (ETDEWEB)

Borges, L.H.C. [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas, Santo Andre, SP (Brazil); Barone, F.A. [IFQ-Universidade Federal de Itajuba, Itajuba, MG (Brazil)

2016-02-15

Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schroedinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector. (orig.)

Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

International Nuclear Information System (INIS)

Borges, L.H.C.; Barone, F.A.

2016-01-01

Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schroedinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector. (orig.)

TWO-DIMENSIONAL MODELLING OF ACCIDENTAL FLOOD WAVES PROPAGATION

Directory of Open Access Journals (Sweden)

Lorand Catalin STOENESCU

2011-05-01

Full Text Available The study presented in this article describes a modern modeling methodology of the propagation of accidental flood waves in case a dam break; this methodology is applied in Romania for the first time for the pilot project „Breaking scenarios of Poiana Uzului dam”. The calculation programs used help us obtain a bidimensional calculation (2D of the propagation of flood waves, taking into consideration the diminishing of the flood wave on a normal direction to the main direction; this diminishing of the flood wave is important in the case of sinuous courses of water or with urban settlements very close to the minor river bed. In the case of Poiana Uzului dam, 2 scenarios were simulated with the help of Ph.D. Eng. Dan Stematiu, plausible scenarios but with very little chances of actually producing. The results were presented as animations with flooded surfaces at certain time steps successively.

Dynamics of internal waves on the Southeast Florida shelf: Implications for cross-shelf exchange and turbulent mixing on a barrier reef system

Science.gov (United States)

Davis, Kristen Alexis

The dynamics of internal waves shoaling on the Southeast Florida shelf and the resulting stratified turbulence in the shelf bottom boundary layer are investigated using observational studies completed during the summers of 2003-2005. This work is driven by a desire to understand the effects of internal wave-driven flow and the shoreward transport of cool, nutrient-rich water masses on cross-shelf exchange, vertical mixing, and mass transfer to benthic reef organisms. Shelf sea internal wave fields are typically highly variable and dominated by wind and tidal forces. However, this is not necessarily true for outer shelf regions or very narrow shelves where remote physical processes originating over the slope or deep ocean may exert a strong influence on the internal wave climate. During the summers of 2003 and 2004 observational studies were conducted to examine the effects of a western boundary current (the Florida Current), tides, and wind on the mean currents and internal wave field on the outer Southeast Florida shelf. We present evidence that suggests that the Florida Current plays as large a role in the determination of the high frequency internal wave field as tidal forces. These observations and analyses show that it is necessary to include the forcing from the Florida Current meanders and instabilities in order to predict accurately the episodic nature of the internal wave field on the Southeast Florida shelf. Deep ocean and continental shelf processes intersect at the shelf edge and influence the exchange of water masses and their associated characteristics including heat, nutrients, sediment, and larvae across the shelf. Thus, the dynamics of cross-shelf circulation have important consequences for organisms living on the shelf. In the second phase of this work, we investigate physical mechanisms controlling the exchange of water masses during the summer season across the Southeast Florida shelf. A time series of cross-shelf transport from May to August

Origin and Structure of Nearshore Internal Tides and Waves: Data Analysis and Linear Theory

National Research Council Canada - National Science Library

Hendershott, Myrl

2001-01-01

Analysis of the data set obtained during the 1996-97 summer and autumn deployments of ADCP and T-logger internal wave antennas of Mission Beach, CA, was the principle activity during the reporting period...

Simulation of Wave Overtopping of Maritime Structures in a Numerical Wave Flume

Directory of Open Access Journals (Sweden)

Tiago C. A. Oliveira

2012-01-01

Full Text Available A numerical wave flume based on the particle finite element method (PFEM is applied to simulate wave overtopping for impermeable maritime structures. An assessment of the performance and robustness of the numerical wave flume is carried out for two different cases comparing numerical results with experimental data. In the first case, a well-defined benchmark test of a simple low-crested structure overtopped by regular nonbreaking waves is presented, tested in the lab, and simulated in the numerical wave flume. In the second case, state-of-the-art physical experiments of a trapezoidal structure placed on a sloping beach overtopped by regular breaking waves are simulated in the numerical wave flume. For both cases, main overtopping events are well detected by the numerical wave flume. However, nonlinear processes controlling the tests proposed, such as nonlinear wave generation, energy losses along the wave propagation track, wave reflection, and overtopping events, are reproduced with more accuracy in the first case. Results indicate that a numerical wave flume based on the PFEM can be applied as an efficient tool to supplement physical models, semiempirical formulations, and other numerical techniques to deal with overtopping of maritime structures.

A case study of the energy dissipation of the gravity wave field based on satellite altimeter measurements

Science.gov (United States)

Huang, N. E.; Parsons, C. L.; Long, S. R.; Bliven, L. F.

1983-01-01

Wave breaking is proposed as the primary energy dissipation mechanism for the gravity wave field. The energy dissipation rate is calculated based on the statistical model proposed by Longuet-Higgins (1969) with a modification of the breaking criterion incorporating the surface stress according to Phillips and Banner (1974). From this modified model, an analytic expression is found for the wave attenuation rate and the half-life time of the wave field which depend only on the significant slope of the wave field and the ratio of friction velocity to initial wave phase velocity. These expressions explain why the freshly generated wave field does not last long, but why swells are capable of propagating long distances without substantial change in energy density. It is shown that breaking is many orders of magnitude more effective in dissipating wave energy than the molecular viscosity, if the significant slope is higher than 0.01. Limited observational data from satellite and laboratory are used to compare with the analytic results, and show good agreement.

Consistency of Trend Break Point Estimator with Underspecified Break Number

Directory of Open Access Journals (Sweden)

Jingjing Yang

2017-01-01

Full Text Available This paper discusses the consistency of trend break point estimators when the number of breaks is underspecified. The consistency of break point estimators in a simple location model with level shifts has been well documented by researchers under various settings, including extensions such as allowing a time trend in the model. Despite the consistency of break point estimators of level shifts, there are few papers on the consistency of trend shift break point estimators in the presence of an underspecified break number. The simulation study and asymptotic analysis in this paper show that the trend shift break point estimator does not converge to the true break points when the break number is underspecified. In the case of two trend shifts, the inconsistency problem worsens if the magnitudes of the breaks are similar and the breaks are either both positive or both negative. The limiting distribution for the trend break point estimator is developed and closely approximates the finite sample performance.

Inhomogeneous chiral symmetry breaking in isospin-asymmetric strong-interaction matter

Energy Technology Data Exchange (ETDEWEB)

Nowakowski, Daniel

2017-07-01

In this thesis we investigate the effects of an isospin asymmetry on inhomogeneous chiral symmetry breaking phases, which are characterized by spatially modulated quarkantiquark condensates. In order to determine the relevance of such phases for the phase diagram of strong-interaction matter, a two-flavor Nambu-Jona-Lasinio model is used to study the properties of the ground state of the system. Confirming the presence of inhomogeneous chiral symmetry breaking in isospin-asymmetric matter for a simple Chiral Density Wave, we generalize the modulation of the quark-antiquark pairs to more complicated shapes and study the effects of different degrees of flavor-mixing on the inhomogeneous phase at non-zero isospin asymmetry. Then, we investigate the occurrence of crystalline chiral symmetry breaking phases in charge-neutral matter, from which we determine the influence of crystalline phases on a quark star by calculating mass-radius sequences. Finally, our model is extended through color-superconducting phases and we study the interplay of these phases with inhomogeneous chiral-symmetry breaking at non-vanishing isospin asymmetry, before we discuss our findings.

Stratified flows and internal waves in the Vema Fracture Zone of the Mid Atlantic Ridge

Science.gov (United States)

Makarenko, Nikolay; Morozov, Eugene; Tarakanov, Roman; Demidova, Tatiana; Frey, Dmitri; Grigorenko, Klim

2017-04-01

In this paper, we study stratified flows and internal waves in the Vema fracture zone of the Mid Atlantic Ridge. This fracture provides intense transportation of cold abyssal waters from the West Atlantic to the equatorial region of the East Atlantic [1]. The results of measurements [2,3] carried out in the cruises of RV Akademik Sergey Vavilov in 2014-2016 are presented. The structure of the near-bottom flow is studied experimentally on the basis of CTD- and LADCP profiling. Theoretical analysis involves mathematical formulation of stratified fluid flow which uses CTD-data obtained from field observation. Spectral properties and kinematic characteristics of internal waves are calculated and discussed. This work was supported by RFBR (grants No 15-01-03942, 16-35-50158). References [1] Morozov E., Demidov A., Tarakanov R. and Zenk W. Abyssal Channels in the Atlantic Ocean: Water Structure and Flows, Springer, Dordrecht, 2010. [2] Morozov E.G., Tarakanov R.Yu., and Makarenko N.I. Flows of Antarctic Bottom Water through fractures in the southern part of the North Mid Atlantic Ridge, Oceanology, 2015, 55, 796-800. [3] Grigorenko K.S., Makarenko N.I., Morozov E.G., Tarakanov R.Yu., and Frey D.I. Stratified flows and internal waves in the Central West Atlantic, J. Physics: Conf. Series, 2016, 722, 012011.

The International Pulsar Timing Array project: using pulsars as a gravitational wave detector

NARCIS (Netherlands)

Hobbs, G.; Archibald, A.; Arzoumanian, Z.; Backer, D.; Bailes, M.; Bhat, N.D.R.; Burgay, M.; Burke-Spolaor, S.; Champion, D.; Cognard, I.; Coles, W.; Cordes, J.; Demorest, P.; Desvignes, G.; Ferdman, R.D.; Finn, L.; Freire, P.; Gonzalez, M.; Hessels, J.; Hotan, A.; Janssen, G.; Jenet, F.; Jessner, A.; Jordan, C.; Kaspi, V.; Kramer, M.; Kondratiev, V.; Lazio, J.; Lazaridis, K.; Lee, K.J.; Levin, Y.; Lommen, A.; Lorimer, D.; Lynch, R.; Lyne, A.; Manchester, R.; McLaughlin, M.; Nice, D.; Oslowski, S.; Pilia, M.; Possenti, A.; Purver, M.; Ransom, S.; Reynolds, J.; Sanidas, S.; Sarkissian, J.; Sesana, A.; Shannon, R.; Siemens, X.; Stairs, I.; Stappers, B.; Stinebring, D.; Theureau, G.; van Haasteren, R.; van Straten, W.; Verbiest, J.P.W.; Yardley, D.R.B.; You, X.P.

2010-01-01

The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim of detecting ultra-low frequency (similar to 10(-9)-10(-8) Hz) gravitational waves. Here we introduce the project, review the methods used to

Algebraic internal wave solitons and the integrable Calogero--Moser--Sutherland N-body problem

International Nuclear Information System (INIS)

Chen, H.H.; Lee, Y.C.; Pereira, N.R.

1979-01-01

The Benjamin--Ono equation that describes nonlinear internal waves in a stratified fluid is solved by a pole expansion method. The dynamics of poles which characterize solitons is shown to be identical to the well-known integrable N-body problem of Calogero, Moser, and Sutherland

Break-up stage restoration in multifragmentation reactions

Energy Technology Data Exchange (ETDEWEB)

Raduta, Ad.R. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay cedex (France)]|[NIPNE, Bucharest-Magurele, POB-MG 6 (Romania); Bonnet, E.; Borderie, B.; Le Neindre, N.; Rivet, M.F. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay cedex (France); Piantelli, S. [Dip. di Fisica e Sezione INFN, Universita di Firenze, I-50019 Sesto Fiorentino, Fi (Italy)

2007-02-15

In the case of Xe+Sn at 32 MeV/nucleon multifragmentation reaction break-up fragments are built-up from the experimentally detected ones using evaluations of light particle evaporation multiplicities which thus settle fragment internal excitation. Freeze-out characteristics are extracted from experimental kinetic energy spectra under the assumption of full decoupling between fragment formation and energy dissipated in different degrees of freedom. Thermal kinetic energy is determined uniquely while for freeze-out volume - collective energy a multiple solution is obtained. Coherence between the solutions of the break-up restoration algorithm and the predictions of a multifragmentation model with identical definition of primary fragments is regarded as a way to select the true value. The broad kinetic energy spectrum of {sup 3}He is consistent with break-up genesis of this isotope. (authors)

Break-up stage restoration in multifragmentation reactions

International Nuclear Information System (INIS)

Raduta, Ad.R.; Bonnet, E.; Borderie, B.; Le Neindre, N.; Rivet, M.F.; Piantelli, S.

2007-02-01

In the case of Xe+Sn at 32 MeV/nucleon multifragmentation reaction break-up fragments are built-up from the experimentally detected ones using evaluations of light particle evaporation multiplicities which thus settle fragment internal excitation. Freeze-out characteristics are extracted from experimental kinetic energy spectra under the assumption of full decoupling between fragment formation and energy dissipated in different degrees of freedom. Thermal kinetic energy is determined uniquely while for freeze-out volume - collective energy a multiple solution is obtained. Coherence between the solutions of the break-up restoration algorithm and the predictions of a multifragmentation model with identical definition of primary fragments is regarded as a way to select the true value. The broad kinetic energy spectrum of 3 He is consistent with break-up genesis of this isotope. (authors)

Simulations for design and reconstruction of breaking waves in a wavetank

NARCIS (Netherlands)

Kurnia, Ruddy; van den Munckhof, T.; Poot, C.P.; Naaijen, P.; Huijsmans, R.H.M.; van Groesen, Embrecht W.C.

To determine forces on fixed and flexible structures such as wind mills and oil platforms, experiments in wave tanks are useful to investigate the impacts in various types of environmental waves. In this paper we show that the use of an efficient simulation code can optimize the experiments by

Convective cells of internal gravity waves in the earth's atmosphere with finite temperature gradient

Directory of Open Access Journals (Sweden)

O. Onishchenko

2013-03-01

Full Text Available In this paper, we have investigated vortex structures (e.g. convective cells of internal gravity waves (IGWs in the earth's atmosphere with a finite vertical temperature gradient. A closed system of nonlinear equations for these waves and the condition for existence of solitary convective cells are obtained. In the atmosphere layers where the temperature decreases with height, the presence of IGW convective cells is shown. The typical parameters of such structures in the earth's atmosphere are discussed.

Modeling wave attenuation by salt marshes in Jamaica Bay, New York, using a new rapid wave model

Science.gov (United States)

Marsooli, Reza; Orton, Philip M.; Mellor, George

2017-07-01

Using a new rapid-computation wave model, improved and validated in the present study, we quantify the value of salt marshes in Jamaica Bay—a highly urbanized estuary located in New York City—as natural buffers against storm waves. We augment the MDO phase-averaged wave model by incorporating a vegetation-drag-induced energy dissipation term into its wave energy balance equation. We adopt an empirical formula from literature to determine the vegetation drag coefficient as a function of environmental conditions. Model evaluation using data from laboratory-scale experiments show that the improved MDO model accurately captures wave height attenuation due to submerged and emergent vegetation. We apply the validated model to Jamaica Bay to quantify the influence of coastal-scale salt marshes on storm waves. It is found that the impact of marsh islands is largest for storms with lower flood levels, due to wave breaking on the marsh island substrate. However, the role of the actual marsh plants, Spartina alterniflora, grows larger for storms with higher flood levels, when wave breaking does not occur and the vegetative drag becomes the main source of energy dissipation. For the latter case, seasonality of marsh height is important; at its maximum height in early fall, S. alterniflora causes twice the reduction as when it is at a shorter height in early summer. The model results also indicate that the vegetation drag coefficient varies 1 order of magnitude in the study area, and suggest exercising extra caution in using a constant drag coefficient in coastal wetlands.

Unification of SUSY breaking and GUT breaking

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Tatsuo [Department of Physics, Hokkaido University,Sapporo 060-0810 (Japan); Omura, Yuji [Department of Physics, Nagoya University,Nagoya 464-8602 (Japan)

2015-02-18

We build explicit supersymmetric unification models where grand unified gauge symmetry breaking and supersymmetry (SUSY) breaking are caused by the same sector. Besides, the SM-charged particles are also predicted by the symmetry breaking sector, and they give the soft SUSY breaking terms through the so-called gauge mediation. We investigate the mass spectrums in an explicit model with SU(5) and additional gauge groups, and discuss its phenomenological aspects. Especially, nonzero A-term and B-term are generated at one-loop level according to the mediation via the vector superfields, so that the electro-weak symmetry breaking and 125 GeV Higgs mass may be achieved by the large B-term and A-term even if the stop mass is around 1 TeV.

Break the Pattern!

DEFF Research Database (Denmark)

Hasse, Cathrine; Trentemøller, Stine

Break the Pattern! A critical enquiry into three scientific workplace cultures: Hercules, Caretakers and Worker Bees is the third publication of the international three year long project "Understanding Puzzles in the Gendered European Map" (UPGEM). By contrasting empirical findings from academic ...... (physics in culture) and discuss how physics as and in culture influence the perception of science, of work and family life, of the interplay between religion and science as well as how physics as culture can either hinder or promote the career of female scientists....

Hypothetical Mine Hunting Sonar - Internal Wave Impact on Performance

Science.gov (United States)

2014-12-09

5e-02 1 OeOO~. ?’•’~~~·0 0 20 40 60 SE dB 80 100 120 Histogrilm of SE45200 FM=174 w=BO 11e-01l 𔃺 5 e-0 2 I n. nUn ~ OeOO -4...question its use as a reliable mine detection system. This signal excess variability study needs to be improved in a number of ways: 1. the impact of...profile and its perturbation by the seasonally changing internal wave fields needs to be addressed and 4. acoustic signal propagation studies focused

Response of internal solitary waves to tropical storm Washi in the northwestern South China Sea

Directory of Open Access Journals (Sweden)

Z. H. Xu

2011-11-01

Full Text Available Based on in-situ time series data from an array of temperature sensors and an acoustic Doppler current profiler on the continental shelf of the northwestern South China Sea, a sequence of internal solitary waves (ISWs were observed during the passage of tropical storm Washi in the summer of 2005, which provided a unique opportunity to investigate the ISW response to the tropical cyclone. The passing tropical storm is found to play an important role in affecting the stratification structure of the water column, and consequently leading to significant variability in the propagating features of the ISWs, such as the polarity reversal and amplitude variations of the waves. The response of the ISWs to Washi can be divided into two stages, direct forcing by the strong wind (during the arrival of Washi and remote forcing via the near-inertial internal waves induced by the tropical storm (after the passage of Washi. The field observations as well as a theoretical analysis suggest that the variations of the ISWs closely coincide with the changing stratification structure and shear currents in accompanied by the typhoon wind and near-inertial waves. This study presents the first observations and analysis of the ISW response to the tropical cyclone in the South China Sea.

The Effects of Surface Gravity Waves on Coastal Currents: Implementation, Phenomenological Explanation, and Realistic Simulation with ROMS

National Research Council Canada - National Science Library

McWilliams, James C; Uchiyama, Yusuke

2008-01-01

... (Uchiyama and McWilliams, 2008). An investigation of shear instability due to breaking-wave-driven barotropic littoral currents on a barred beach is being carried out by extending the asymptotic theory appropriate for a strong current regime near surf zones with a parameterized, non-conservative wave breaking (Uchiyama et al., 2008).

Numerical simulation of lowest-order short-crested wave instabilities

DEFF Research Database (Denmark)

Fuhrman, David R.; Madsen, Per A.; Bingham, Harry

2006-01-01

instabilities. These correctly lead to well-known (nearly symmetric) recurrence cycles below a previously established breaking threshold steepness, and to an asymmetric evolution (characterized by a permanent transfer of energy to the lower side-band) above this threshold, with dissipation from a smoothing...... that the unstable evolution of these initially three-dimensional waves leads to an asymmetric evolution, even for weakly nonlinear cases presumably well below breaking. This is characterized by an energy transfer to the lower side-band, which is also accompanied by a similar transfer to more distant upper side......-bands. At larger steepness, the evolution leads to a permanent downshift of both the mean and peak frequencies, driven in part by dissipation, effectively breaking the quasi-recurrence cycle. A single case involving a class Ib short-crested wave instability at relatively large steepness is also considered, which...

Experimental determination of radiated internal wave power without pressure field data

Science.gov (United States)

Lee, Frank M.; Paoletti, M. S.; Swinney, Harry L.; Morrison, P. J.

2014-04-01

We present a method to determine, using only velocity field data, the time-averaged energy flux left and total radiated power P for two-dimensional internal gravity waves. Both left and P are determined from expressions involving only a scalar function, the stream function ψ. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method agree to within 0.5% with results obtained using pressure and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and pressure if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data.

Experimental determination of radiated internal wave power without pressure field data

International Nuclear Information System (INIS)

Lee, Frank M.; Morrison, P. J.; Paoletti, M. S.; Swinney, Harry L.

2014-01-01

We present a method to determine, using only velocity field data, the time-averaged energy flux (J) and total radiated power P for two-dimensional internal gravity waves. Both (J) and P are determined from expressions involving only a scalar function, the stream function ψ. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method agree to within 0.5% with results obtained using pressure and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and pressure if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data

High-frequency internal waves and thick bottom mixed layers observed by gliders in the Gulf Stream

Science.gov (United States)

Todd, Robert E.

2017-06-01

Autonomous underwater gliders are conducting high-resolution surveys within the Gulf Stream along the U.S. East Coast. Glider surveys reveal two mechanisms by which energy is extracted from the Gulf Stream as it flows over the Blake Plateau, a portion of the outer continental shelf between Florida and North Carolina where bottom depths are less than 1000 m. Internal waves with vertical velocities exceeding 0.1 m s-1 and frequencies just below the local buoyancy frequency are routinely found over the Blake Plateau, particularly near the Charleston Bump, a prominent topographic feature. These waves are likely internal lee waves generated by the subinertial Gulf Stream flow over the irregular bathymetry of the outer continental shelf. Bottom mixed layers with O(100) m thickness are also frequently encountered; these thick bottom mixed layers likely form in the lee of topography due to enhanced turbulence generated by O(1) m s-1 near-bottom flows.

Seasonal Variations of Mesospheric Gravity Waves Observed with an Airglow All-sky Camera at Mt. Bohyun, Korea (36° N

Directory of Open Access Journals (Sweden)

Yong Ha Kim

2010-09-01

Full Text Available We have carried out all-sky imaging of OH Meinel, O2 atmospheric and OI 557.7 nm airglow layers in the period from July of 2001 through September of 2005 at Mt. Bohyun, Korea (36.2° N, 128.9° E, Alt = 1,124 m. We analyzed the images observed during a total of 153 clear moonless nights and found 97 events of band-type waves. The characteristics of the observed waves (wavelengths, periods, and phase speeds are consistent with internal gravity waves. The wave occurrence shows an approximately semi-annual variation, with maxima near solstices and minima near equinoxes, which is consistent with other studies of airglow wave observations, but not with those of mesospheric radar/lidar observations. The observed waves tended to propagate westward during fall and winter, and eastward during spring and summer. Our ray tracing study of the observed waves shows that majority of the observed waves seemed to originate from mesospheric altitudes. The preferential directions and the apparent source altitudes can be explained if the observed waves are secondary waves generated from primary waves that have been selected by the filtering process and break up at the mesospheric altitudes.

Internal structure of laser supported detonation waves by two-wavelength Mach-Zehnder interferometer

International Nuclear Information System (INIS)

Shimamura, Kohei; Kawamura, Koichi; Fukuda, Akio; Wang Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Hatai, Keigo; Fukui, Akihiro; Arakawa, Yoshihiro

2011-01-01

Characteristics of the internal structure of the laser supported detonation (LSD) waves, such as the electron density n e and the electron temperature T e profiles behind the shock wave were measured using a two-wavelength Mach-Zehnder interferometer along with emission spectroscopy. A TEA CO 2 laser with energy of 10 J/pulse produced explosive laser heating in atmospheric air. Results show that the peak values of n e and T e were, respectively, about 2 x 10 24 m -3 and 30 000 K, during the LSD regime. The temporal variation of the laser absorption coefficient profile estimated from the measured properties reveals that the laser energy was absorbed perfectly in a thin layer behind the shock wave during the LSD regime, as predicted by Raizer's LSD model. However, the absorption layer was much thinner than a plasma layer, the situation of which was not considered in Raizer's model. The measured n e at the shock front was not zero while the LSD was supported, which implies that the precursor electrons exist ahead of the shock wave.

Wave Transformation for International Hub Port Planning (Transformasi Gelombang untuk Perencanaan Pelabuhan Hub Internasional

Directory of Open Access Journals (Sweden)

Denny Nugroho Sugianto

2015-02-01

archipelagic countries in the world, therefore port has vital role in economic development. Port is not just as a complement to the infrastructure, but it must be planned and managed properly and attention to the dynamics of marine phenomena such as ocean wave patterns. Ocean wave data become important factors in planning coastal building, since it is influenced by wave height, tides and waves transformation. The purpose of this study was to analyse characteristic and forms wave transformations for planning of international hub port at Kuala Tanjung, Baru Bara District North Sumatra. This port is one of two Indonesian government's plan in the development of international hub port. Quantitative method was used in this study by statistical calculations and mathematical modeling with hydrodinamic modules and spectral wave to determine the direction of wave propagation and transformation. Results show that based on ECMWF data during 1999-June 2014, known significant wave height (Hs maximum of 1.69 m and maximum period (Ts of 8 secs. The classification wave characteristics iswave transition (d.L-1: 0.27–0.48 and by the period are classified as gravitational waves. Wave transformation occurs due to the soaling, withKs 0.93–0.98 and the wave refraction Kr 0.97–0.99. Whereas Hb of 1.24 meters anddb 1.82 meters. The effectiveness of the design of the terminal building at the Port of Kuala Tanjung overall for the season amounted to 79.8%, which is quite effective in reducing the wave. Keywords: wave transformation, wave height and period, Port of Kuala Tanjung

Toughening elastomers with sacrificial bonds and watching them break.

Science.gov (United States)

Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

2014-04-11

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

Transfer and dissipation of energy during wave group propagation on a gentle beach slope

Science.gov (United States)

Padilla, Enrique M.; Alsina, José M.

2017-08-01

The propagation of bichromatic wave groups over a constant 1:100 beach slope and the influence of the group modulation is presented. The modulation is controlled by varying the group frequency, fg, which is shown to remarkably affect the energy transfer to high and low frequency components. The growth of the high frequency (hf) wave skewness increases when fg decreases. This is explained by nonlinear coupling between the primary frequencies, which results in a larger growth of hf components as fg decreases, causing the hf waves to break earlier. Due to high spatial resolution, wave tracking has provided an accurate measurement of the varying breakpoint. These breaking locations are very well described (R2>0.91) by the wave-height to effective-depth ratio (γ). However, for any given Iribarren number, this γ is shown to increase with fg. Therefore, a modified Iribarren number is proposed to include the grouping structure, leading to a considerable improvement in reproducing the measured γ-values. Within the surf zone, the behavior of the Incident Long Wave also depends on the group modulation. For low fg conditions, the lf wave decays only slightly by transferring energy back to the hf wave components. However, for high fg wave conditions, strong dissipation of low frequency (lf) components occurs close to the shoreline associated with lf wave breaking. This mechanism is explained by the growth of the lf wave height, induced partly by the self-self interaction of fg, and partly by the nonlinear coupling between the primary frequencies and fg.

Internal gravity waves in Titan's atmosphere observed by Voyager radio occultation

Science.gov (United States)

Hinson, D. P.; Tyler, G. L.

1983-01-01

The radio scintillations caused by scattering from small-scale irregularities in Titan's neutral atmosphere during a radio occultation of Voyager 1 by Titan are investigated. Intensity and frequency fluctuations occurred on time scales from about 0.1 to 1.0 sec at 3.6 and 13 cm wavelengths whenever the radio path passed within 90 km of the surface, indicating the presence of variations in refractivity on length scales from a few hundred meters to a few kilometers. Above 25 km, the altitude profile of intensity scintillations closely agrees with the predictions of a simple theory based on the characteristics of internal gravity waves propagating with little or no attenuation through the vertical stratification in Titan's atmosphere. These observations support a hypothesis of stratospheric gravity waves, possibly driven by a cloud-free convective region in the lowest few kilometers of the stratosphere.

A statistical study of variations of internal gravity wave energy characteristics in meteor zone

Science.gov (United States)

Gavrilov, N. M.; Kalov, E. D.

1987-01-01

Internal gravity wave (IGW) parameters obtained by the radiometer method have been considered by many other researchers. The results of the processing of regular radiometeor measurements taken during 1979 to 1980 in Obninsk (55.1 deg N, 36.6 deg E) are presented.

Competition between the symmetry breaking and onset of collapse in weakly coupled atomic condensates

International Nuclear Information System (INIS)

Salasnich, L.; Toigo, F.; Malomed, B. A.

2010-01-01

We analyze the symmetry breaking of matter-wave solitons in a pair of cigar-shaped traps coupled by tunneling of atoms. The model is based on a system of linearly coupled nonpolynomial Schroedinger equations. Unlike the well-known spontaneous-symmetry-breaking (SSB) bifurcation in coupled cubic equations, in the present model the SSB competes with the onset of collapse in this system. Stability regions of symmetric and asymmetric solitons, as well as the collapse region, are identified in the system's parameter space.

The lifecycle of axisymmetric internal solitary waves

Directory of Open Access Journals (Sweden)

J. M. McMillan

2010-09-01

Full Text Available The generation and evolution of solitary waves by intrusive gravity currents in an approximate two-layer fluid with equal upper- and lower-layer depths is examined in a cylindrical geometry by way of theory and numerical simulations. The study is limited to vertically symmetric cases in which the density of the intruding fluid is equal to the average density of the ambient. We show that even though the head height of the intrusion decreases, it propagates at a constant speed well beyond 3 lock radii. This is because the strong stratification at the interface supports the formation of a mode-2 solitary wave that surrounds the intrusion head and carries it outwards at a constant speed. The wave and intrusion propagate faster than a linear long wave; therefore, there is strong supporting evidence that the wave is indeed nonlinear. Rectilinear Korteweg-de Vries theory is extended to allow the wave amplitude to decay as r^-p with p=½ and the theory is compared to the observed waves to demonstrate that the width of the wave scales with its amplitude. After propagating beyond 7 lock radii the intrusion runs out of fluid. Thereafter, the wave continues to spread radially at a constant speed, however, the amplitude decreases sufficiently so that linear dispersion dominates and the amplitude decays with distance as r^-1.

The Newton constant and gravitational waves in some vector field adjusting mechanisms

Energy Technology Data Exchange (ETDEWEB)

Santillán, Osvaldo P. [IMAS (UBA-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina); Scornavacche, Marina, E-mail: firenzecita@hotmail.com, E-mail: marina.scorna@hotmail.com [Departamento de Física, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina)

2017-10-01

At the present, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant at the present era [1]–[2]. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant G {sub N} in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant G {sub N} or introduce longitudinal modes in the gravitational wave propagation. Furthermore this breaking may spoil the standard dispersion relation ω= ck . In [3] the authors have presented a model suggesting that the behavior of the gravitational constant is correct for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.

The role of Internal Solitary Waves on deep-water sedimentary processes: the case of up-slope migrating sediment waves off the Messina Strait

Science.gov (United States)

Droghei, R.; Falcini, F.; Casalbore, D.; Martorelli, E.; Mosetti, R.; Sannino, G.; Santoleri, R.; Chiocci, F. L.

2016-11-01

Subaqueous, asymmetric sand waves are typically observed in marine channel/canyon systems, tidal environments, and continental slopes exposed to strong currents, where they are formed by current shear resulting from a dominant unidirectional flow. However, sand-wave fields may be readily observed in marine environments where no such current exists; the physical processes driving their formation are enigmatic or not well understood. We propose that internal solitary waves (ISWs) induced by tides can produce an effective, unidirectional boundary “current” that forms asymmetric sand waves. We test this idea by examining a sand-wave field off the Messina Strait, where we hypothesize that ISWs formed at the interface between intermediate and surface waters are refracted by topography. Hence, we argue that the deflected pattern (i.e., the depth-dependent orientation) of the sand-wave field is due to refraction of such ISWs. Combining field observations and numerical modelling, we show that ISWs can account for three key features: ISWs produce fluid velocities capable of mobilizing bottom sediments; the predicted refraction pattern resulting from the interaction of ISWs with bottom topography matches the observed deflection of the sand waves; and predicted migration rates of sand waves match empirical estimates. This work shows how ISWs may contribute to sculpting the structure of continental margins and it represents a promising link between the geological and oceanographic communities.

A New International Standard for "Actions from Waves and Currents on Coastal Structures"

DEFF Research Database (Denmark)

Tørum, Alf; Burcharth, Hans F.; Goda, Yoshimi

2007-01-01

The International Organization for Standardization (ISO) is going to issue a new standard concerning "Actions from Waves and Currents on Coastal Structures," which becomes the first international standard in coastal engineering. It is composed of a normative part (29 pages), an informative part (80...... pages) and Bibliography ( 17 pages). The normative part describes what is considered as the norm of the matters in concern, while the informative part provides the information on recommended practice. The paper introduces the main points of the normative part and discusses the influence of the new...

Detection of surface breaking cracks in centrifugally cast stainless steel with ultrasonic - Inspection from the cracked side

International Nuclear Information System (INIS)

Hoegberg, K.; Zetterwall, T.

1986-01-01

The ability of detecting surface breaking or near-surface cracks with ultrasonic techniques from the inside of centrifugally cast stainless steel pipes have been investigated by the Swedish Plant Inspectorate (SA) and AaF-Tekniska Roentgencentralen AB (AaF-TRC) on behalf of the Swedish Nuclear Power Inspectorate (SKI) and the Swedish State Power Board (SV). Fifteen specimens from the international Stainless Steel Round Robin Test (SSRRT) were used in this study. All specimens were examined from the cracked side with different ultrasonic probes. The data reported here indicate that a probe with dual elements, low frequency, longitudinal waves and short focus distance can detect almost all of the intended defects with a rather good signal-to-noise ratio. (author)

Solitary wave and periodic wave solutions for the thermally forced gravity waves in atmosphere

International Nuclear Information System (INIS)

Li Ziliang

2008-01-01

By introducing a new transformation, a new direct and unified algebraic method for constructing multiple travelling wave solutions of general nonlinear evolution equations is presented and implemented in a computer algebraic system, which extends Fan's direct algebraic method to the case when r > 4. The solutions of a first-order nonlinear ordinary differential equation with a higher degree nonlinear term and Fan's direct algebraic method of obtaining exact solutions to nonlinear partial differential equations are applied to the combined KdV-mKdV-GKdV equation, which is derived from a simple incompressible non-hydrostatic Boussinesq equation with the influence of thermal forcing and is applied to investigate internal gravity waves in the atmosphere. As a result, by taking advantage of the new first-order nonlinear ordinary differential equation with a fifth-degree nonlinear term and an eighth-degree nonlinear term, periodic wave solutions associated with the Jacobin elliptic function and the bell and kink profile solitary wave solutions are obtained under the effect of thermal forcing. Most importantly, the mechanism of propagation and generation of the periodic waves and the solitary waves is analysed in detail according to the values of the heating parameter, which show that the effect of heating in atmosphere helps to excite westerly or easterly propagating periodic internal gravity waves and internal solitary waves in atmosphere, which are affected by the local excitation structures in atmosphere. In addition, as an illustrative sample, the properties of the solitary wave solution and Jacobin periodic solution are shown by some figures under the consideration of heating interaction

Noncritical quadrature squeezing through spontaneous polarization symmetry breaking

OpenAIRE

Garcia-Ferrer, Ferran V.; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J.; Roldán, Eugenio

2010-01-01

We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We consider first type-II frequency-degenerate optical parametric oscillators, but discard them for a number of reasons. Then we propose a four-wave mixing cavity in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity complete noise suppression in a quadrature of the output field occurs, irrespective of ...

Noncritical quadrature squeezing through spontaneous polarization symmetry breaking.

Science.gov (United States)

Garcia-Ferrer, Ferran V; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J; Roldán, Eugenio

2010-07-01

We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We first consider Type II frequency-degenerate optical parametric oscillators but discard them for a number of reasons. Then we propose a four-wave-mixing cavity, in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity, complete noise suppression in a quadrature of the output field occurs, irrespective of the parameter values.

Lecture Notes for the Course in Water Wave Mechanics

DEFF Research Database (Denmark)

Andersen, Thomas Lykke; Frigaard, Peter; Burcharth, Hans F.

knowledge. The course is at the same time an introduction to the course in coastal hydraulics on the 8th semester. The notes cover the first four lectures of the course: • Definitions. Governing equations and boundary conditions. • Derivation of velocity potential for linear waves. Dispersion relationship...... Particle velocities and accelerations. • Particle paths, pressure variation, deep and shallow water waves, wave energy and group velocity. • Shoaling, refraction, diffraction and wave breaking. The last part of the course is on analysis of irregular waves and was included in the first two editions...

PT-symmetry breaking in complex nonlinear wave equations and their deformations

International Nuclear Information System (INIS)

Cavaglia, Andrea; Fring, Andreas; Bagchi, Bijan

2011-01-01

We investigate complex versions of the Korteweg-deVries equations and an Ito-type nonlinear system with two coupled nonlinear fields. We systematically construct rational, trigonometric/hyperbolic and elliptic solutions for these models including those which are physically feasible in an obvious sense, that is those with real energies, but also those with complex energy spectra. The reality of the energy is usually attributed to different realizations of an antilinear symmetry, as for instance PT-symmetry. It is shown that the symmetry can be spontaneously broken in two alternative ways either by specific choices of the domain or by manipulating the parameters in the solutions of the model, thus leading to complex energies. Surprisingly, the reality of the energies can be regained in some cases by a further breaking of the symmetry on the level of the Hamiltonian. In many examples, some of the fixed points in the complex solution for the field undergo a Hopf bifurcation in the PT-symmetry breaking process. By employing several different variants of the symmetries we propose many classes of new invariant extensions of these models and study their properties. The reduction of some of these models yields complex quantum mechanical models previously studied.

ONR Ocean Wave Dynamics Workshop

Science.gov (United States)

In anticipation of the start (in Fiscal Year 1988) of a new Office of Naval Research (ONR) Accelerated Research Initiative (ARI) on Ocean Surface Wave Dynamics, a workshop was held August 5-7, 1986, at Woods Hole, Mass., to discuss new ideas and directions of research. This new ARI on Ocean Surface Wave Dynamics is a 5-year effort that is organized by the ONR Physical Oceanography Program in cooperation with the ONR Fluid Mechanics Program and the Physical Oceanography Branch at the Naval Ocean Research and Development Activity (NORDA). The central theme is improvement of our understanding of the basic physics and dynamics of surface wave phenomena, with emphasis on the following areas: precise air-sea coupling mechanisms,dynamics of nonlinear wave-wave interaction under realistic environmental conditions,wave breaking and dissipation of energy,interaction between surface waves and upper ocean boundary layer dynamics, andsurface statistical and boundary layer coherent structures.

Lamb wave scattering by a surface-breaking crack in a plate

Science.gov (United States)

Datta, S. K.; Al-Nassar, Y.; Shah, A. H.

1991-01-01

An NDE method based on finite-element representation and modal expansion has been developed for solving the scattering of Lamb waves in an elastic plate waveguide. This method is very powerful for handling discontinuities of arbitrary shape, weldments of different orientations, canted cracks, etc. The advantage of the method is that it can be used to study the scattering of Lamb waves in anisotropic elastic plates and in multilayered plates as well.

Limits of applicability of the quasilinear approximation to the electrostatic wave-plasma interaction

Science.gov (United States)

Zacharegkas, Georgios; Isliker, Heinz; Vlahos, Loukas

2016-11-01

The limitation of the Quasilinear Theory (QLT) to describe the diffusion of electrons and ions in velocity space when interacting with a spectrum of large amplitude electrostatic Langmuir, Upper and Lower hybrid waves, is analyzed. We analytically and numerically estimate the threshold for the amplitude of the waves above which the QLT breaks down, using a test particle code. The evolution of the velocity distribution, the velocity-space diffusion coefficients, the driven current, and the heating of the particles are investigated, for the interaction with small and large amplitude electrostatic waves, that is, in both regimes, where QLT is valid and where it clearly breaks down.

Rock Directed Breaking Under the Impulse Load

Science.gov (United States)

Khomeriki, Sergo; Mataradze, Edgar; Chikhradze, Nikoloz; Losaberidze, Marine; Khomeriki, Davit; Shatberashvili, Grigol

2016-10-01

In the work the problem of directed chipping of facing stone material by means of managing of explosion process is considered. The technology of the mining of decorative stone by the use of explosion energy means the very rapid transfer of potential energy of elastic deformations to kinetic energy. As a result, the explosion impulse, in the expanse of the inertia of rock massive, does not cause the increase of existing cracks. In the course of explosion, the shock wave is propagated by ultrasonic velocity and in this case the medium parameters (pressure, density, temperature, velocity) increase in spurts. In spite of this fact the all three conservation laws of mechanics remain valid on basis of three laws the equations are derived by which the parameters of shock wave may be defined by means of the rock physical-mechanical properties. The load on the body volume at breaking under explosion acts over very small period of the time. Therefore, stressed-deformed state of the rock was studied when the impulse load acts on the boundary. It was considered that the mining of the blocks of facing stone is performed from the hard rocks. This means that the breaking proceeds in the zone of elastic deformation. In the conditions of mentioned assumptions, the expression of the stress tensor and displacement of vector components initiated by stressed-deformed state in the rock are written.

Internal waves over the shelf in the western Bay of Bengal: A case study

Digital Repository Service at National Institute of Oceanography (India)

Joshi, M.; Rao, A.D.; Mohanty, S.; Pradhan, H.K.; Murty, V.S.N.; RamPrasad, K.V.S.

.csr.2005.04.011 Cooley JW, Tukey JW (1965) An algorithm for the machine calculation of complex fourier series. Math Comput 19:297–301 D’Asaro EA, Lien R-C, Henyey F (2007) High-frequency internal waves on the oregon continental shelf. J Phys Oceanogr 37...

Determination of times maximum insulation in case of internal flooding by pipe break

International Nuclear Information System (INIS)

Varas, M. I.; Orteu, E.; Laserna, J. A.

2014-01-01

This paper demonstrates the process followed in the preparation of the Manual of floods of Cofrentes NPP to identify the allowed maximum time available to the central in the isolation of a moderate or high energy pipe break, until it affects security (1E) participating in the safe stop of Reactor or in pools of spent fuel cooling-related equipment , and to determine the recommended isolation mode from the point of view of the location of the break or rupture, of the location of the 1E equipment and human factors. (Author)

Break up of light ions in the nuclear and Coulomb field of nuclei

International Nuclear Information System (INIS)

Srivastava, D.K.

1985-12-01

The break up of light ion projectiles in the nuclear and Coulomb field of nuclei is considered. Current theoretical concepts for describing break up processes and their theoretical features are discussed. An alternative method, based on a prior-interaction DWBA, is introduced for the calculation of the direct elastic break up cross sections. This method reveals the role of the internal momentum distribution of the break up fragments and includes corresponding 'finite range' effects. The Coulomb break up of 6 Li is studied on the basis of a quasi-sequential break up approach (following Rybicki and Austern) and results are obtained for very low relative energies of the emerging α-particles and deuteron fragments. The astrophysical interest in these cross sections is noted. A view on further extensions of the break up theory is given. (orig.) [de

Characterizing the nonlinear internal wave climate in the northeastern South China Sea

Directory of Open Access Journals (Sweden)

S. R. Ramp

2010-09-01

Full Text Available Four oceanographic moorings were deployed in the South China Sea from April 2005 to June 2006 along a transect extending from the Batanes Province, Philippines in the Luzon Strait to just north of Dong-Sha Island on the Chinese continental slope. The purpose of the array was to observe and track large-amplitude nonlinear internal waves (NIWs from generation to shoaling over the course of one full year. The basin and slope moorings observed velocity, temperature (T and salinity (S at 1–3 min intervals to observe the waves without aliasing. The Luzon mooring observed velocity at 15 min and T and S at 3 min, primarily to resolve the tidal forcing in the strait.

The observed waves travelled WNW towards 282–288 degrees with little variation. They were predominantly mode-1 waves with orbital velocities exceeding 100 cm s⁻¹ and thermal displacements exceeding 100 m. Consistent with earlier authors, two types of waves were observed: the a-waves arrived diurnally and had a rank-ordered packet structure. The b-waves arrived in between, about an hour later each day similar to the pattern of the semi-diurnal tide. The b-waves were weaker than the a-waves, usually consisted of just one large wave, and were often absent in the deep basin, appearing as NIW only upon reaching the continental slope. The propagation speed of both types of waves was 323±31 cm s⁻¹ in the deep basin and 222±18 cm s⁻¹ over the continental slope. These speeds were 11–20% faster than the theoretical mode-1 wave speeds for the observed stratification, roughly consistent with the additional contribution from the nonlinear wave amplitude. The observed waves were clustered around the time of the spring tide at the presumed generation site in the Luzon Strait, and no waves were observed at neap tide. A remarkable feature was the distinct lack of waves during the winter months, December 2005 through February

Transformation of Waves Across the Surf Zone.

Science.gov (United States)

1981-03-01

Kuo is more realis- tic but still results in a sharp cut-off of the distribution at the breaking heights. 5. Goda Distribution Goda (1975) derived a...J.I., "Probabilities of Breaking Wave Characteris- tics ," Proc. 12th Coastal Engineering Conf., pp. 399- 412, 1970. Chakrabarty, S.K. and R.P. Cooley...Spring, MD 20910 21. Director 2 Instituto Oceanografico de la Armada Guayaquil, Ecuador 22. Director de Educacion de la Armada Comandancia General de

Infragravity wave generation and dynamics over a mild slope beach : Experiments and numerical computations

Science.gov (United States)

Cienfuegos, R.; Duarte, L.; Hernandez, E.

2008-12-01

Charasteristic frequencies of gravity waves generated by wind and propagating towards the coast are usually comprised between 0.05Hz and 1Hz. Nevertheless, lower frequecy waves, in the range of 0.001Hz and 0.05Hz, have been observed in the nearshore zone. Those long waves, termed as infragravity waves, are generated by complex nonlinear mechanisms affecting the propagation of irregular waves up to the coast. The groupiness of an incident random wave field may be responsible for producing a slow modulation of the mean water surface thus generating bound long waves travelling at the group speed. Similarly, a quasi- periodic oscillation of the break-point location, will be accompained by a slow modulation of set-up/set-down in the surf zone and generation and release of long waves. If the primary structure of the carrying incident gravity waves is destroyed (e.g. by breaking), forced long waves can be freely released and even reflected at the coast. Infragravity waves can affect port operation through resonating conditions, or strongly affect sediment transport and beach morphodynamics. In the present study we investigate infragravity wave generation mechanisms both, from experiments and numerical computations. Measurements were conducted at the 70-meter long wave tank, located at the Instituto Nacional de Hidraulica (Chile), prepared with a beach of very mild slope of 1/80 in order to produce large surf zone extensions. A random JONSWAP type wave field (h0=0.52m, fp=0.25Hz, Hmo=0.17m) was generated by a piston wave-maker and measurements of the free surface displacements were performed all over its length at high spatial resolution (0.2m to 1m). Velocity profiles were also measured at four verticals inside the surf zone using an ADV. Correlation maps of wave group envelopes and infragravity waves are computed in order to identify long wave generation and dynamics in the experimental set-up. It appears that both mechanisms (groupiness and break-point oscillation) are

Gravitational waves from global second order phase transitions

Energy Technology Data Exchange (ETDEWEB)

Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Rd, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier; Vlcek, Brian, E-mail: giblinj@kenyon.edu, E-mail: larryp@caltech.edu, E-mail: siemens@gravity.phys.uwm.edu, E-mail: bvlcek@uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)

2012-11-01

Global second-order phase transitions are expected to produce scale-invariant gravitational wave spectra. In this manuscript we explore the dynamics of a symmetry-breaking phase transition using lattice simulations. We explicitly calculate the stochastic gravitational wave background produced during the transition and subsequent self-ordering phase. We comment on this signal as it compares to the scale-invariant spectrum produced during inflation.

Temporal variability of gravity wave drag - vertical coupling and possible climate links

Science.gov (United States)

Miksovsky, Jiri; Sacha, Petr; Kuchar, Ales; Pisoft, Petr

2017-04-01

In the atmosphere, the internal gravity waves (IGW) are one of the fastest ways of natural information transfer in the vertical direction. Tropospheric changes that result in modification of sourcing, propagation or breaking conditions for IGWs almost immediately influence the distribution of gravity wave drag in the stratosphere. So far most of the related studies deal with IGW impacts higher in the upper stratospheric/mesospheric region and with the modulation of IGWs by planetary waves. This is most likely due to the fact that IGWs induce highest accelerations in the mesosphere and lower thermosphere region. However, the imposed drag force is much bigger in the stratosphere. In the presented analysis, we have assessed the relationship between the gravity wave activity in the stratosphere and other climatic phenomena through statistical techniques. Multivariable regression has been applied to investigate the IGW-related eastward and northward wind tendencies in the CMAM30-SD data, subject to the explanatory variables involving local circulation characteristics (derived from regional configuration of the thermobaric field) as well as the phases of the large-scale internal climate variability modes (ENSO, NAO, QBO). Our tests have highlighted several geographical areas with statistically significant responses of the orographic gravity waves effect to each of the variability modes under investigation; additional experiments have also indicated distinct signs of nonlinearity in some of the links uncovered. Furthermore, we have also applied composite analysis of displaced and split stratospheric polar vortex events (SPV) from CMAM30-SD to focus on how the strength and occurrence of the IGW hotspots can play a role in SPV occurrence and frequency.

Mooring observations of the near-inertial wave wake of Hurricane Ida (2009)

Science.gov (United States)

Pallàs-Sanz, Enric; Candela, Julio; Sheinbaum, Julio; Ochoa, José

2016-12-01

The near-inertial wave wake of Hurricane Ida is examined of the basis of horizontal velocity observations acquired from 7 moorings instrumented with acoustic Doppler current profilers deployed across the shelf break, slope, and at the abyssal plain of the Yucatan Peninsula, from 130 m to ∼3300 m. During the forced stage, background mean-flow consisted on a dominant cyclonic circulation of ∼100 km of diameter intensified toward the Yucatan's shelf (topographic constraint) and bounded by anticyclonic vorticity northeastward (north 25° N). In the low frequency band, subinertial signals of ∈ [5.5-7.5] day period propagating along the Yucatan shelf break. After the passage of Hurricane Ida, energetic near-inertial oscillations spread away from the storm's track over cyclonic vorticity. The wave's Eulerian frequency increases shoreward and toward the Yucatan's shelf. After Ida's passage, mooring data show a contrasting velocity response: semi-diurnal and diurnal tides are enhanced at the shelf break of the Yucatan Peninsula and near-inertial oscillations at the slope and abyssal plain. The near-inertial kinetic energy is largest to the right of the storm track because of the asymmetric wind-stress and amplified due to vorticity trapping near z =-500 m, which is a proxy of the base of the mesoscale structure and where the mean-flow is nearly zero. The blue frequency shifted wave wake propagates downward at ∼57-70 m day-1 and horizontally at 23-28 km day-1 leading a downward vertical energy flux of [1.3-1.6] × 10-2 W m-2. This represents a 7-9% of the total wind power input to near-inertial oscillations that, ultimately, became available for interior ocean mixing. The results suggest that the most energetic wave packet propagated poleward and downward from a broad upwelling region located near the Hurricane's track. The vertical structure of the near-inertial kinetic energy is described as a sum of the first 12 standing vertical modes and as vertically

Spatial Variation of Diapycnal Diffusivity Estimated From Seismic Imaging of Internal Wave Field, Gulf of Mexico

Science.gov (United States)

Dickinson, Alex; White, N. J.; Caulfield, C. P.

2017-12-01

Bright reflections are observed within the upper 1,000 m of the water column along a seismic reflection profile that traverses the northern margin of the Gulf of Mexico. Independent hydrographic calibration demonstrates that these reflections are primarily caused by temperature changes associated with different water masses that are entrained into the Gulf along the Loop Current. The internal wave field is analyzed by automatically tracking 1,171 reflections, each of which is greater than 2 km in length. Power spectra of the horizontal gradient of isopycnal displacement, ϕξx, are calculated from these tracked reflections. At low horizontal wave numbers (kxcpm), ϕξx∝kx-0.2±0.6, in agreement with hydrographic observations of the internal wave field. The turbulent spectral subrange is rarely observed. Diapycnal diffusivity, K, is estimated from the observed internal wave spectral subrange of each tracked reflection using a fine-scale parametrization of turbulent mixing. Calculated values of K vary between 10-8 and 10-4 m2 s-1 with a mean value of K˜4×10-6 m2 s-1. The spatial distribution of turbulent mixing shows that K˜10-7 m2 s-1 away from the shelf edge in the upper 300 m where stratification is strong. Mixing is enhanced by up to 4 orders of magnitude adjacent to the shoaling bathymetry of the continental slope. This overall pattern matches that determined by analyzing nearby suites of CTD casts. However, the range of values recovered by spectral analysis of the seismic image is greater as a consequence of significantly better horizontal resolution.

The internal wave field in Sau reservoir : Observation and modeling of a third vertical mode

OpenAIRE

Vidal Hurtado, Javier; Casamitjana, Xavier; Colomer, Jordi; Serra Putellas, Teresa

2005-01-01

Water withdrawal from Mediterranean reservoirs in summer is usually very high. Because of this, stratification is often continuous and far from the typical two-layered structure, favoring the excitation of higher vertical modes. The analysis of wind, temperature, and current data from Sau reservoir (Spain) shows that the third vertical mode of the internal seiche (baroclinic mode) dominated the internal wave field at the beginning of September 2003. We used a continuous stratification two-dim...

Generation of Internal Waves by Buoyant Bubbles in Galaxy Clusters and Heating of Intracluster Medium

Science.gov (United States)

Zhang, Congyao; Churazov, Eugene; Schekochihin, Alexander A.

2018-05-01

Buoyant bubbles of relativistic plasma in cluster cores plausibly play a key role in conveying the energy from a supermassive black hole to the intracluster medium (ICM) - the process known as radio-mode AGN feedback. Energy conservation guarantees that a bubble loses most of its energy to the ICM after crossing several pressure scale heights. However, actual processes responsible for transferring the energy to the ICM are still being debated. One attractive possibility is the excitation of internal waves, which are trapped in the cluster's core and eventually dissipate. Here we show that a sufficient condition for efficient excitation of these waves in stratified cluster atmospheres is flattening of the bubbles in the radial direction. In our numerical simulations, we model the bubbles phenomenologically as rigid bodies buoyantly rising in the stratified cluster atmosphere. We find that the terminal velocities of the flattened bubbles are small enough so that the Froude number Fr ≲ 1. The effects of stratification make the dominant contribution to the total drag force balancing the buoyancy force. Clear signs of internal waves are seen in the simulations. These waves propagate horizontally and downwards from the rising bubble, spreading their energy over large volumes of the ICM. If our findings are scaled to the conditions of the Perseus cluster, the expected terminal velocity is ˜100 - 200 km s-1 near the cluster cores, which is in broad agreement with direct measurements by the Hitomi satellite.

CSNI specialist meeting on leak-before-break in nuclear reactor piping: proceedings

Energy Technology Data Exchange (ETDEWEB)

1984-08-01

On September 1 and 2, 1983, the CSNI subcommittee on primary system integrity held a special meeting in Monterey, California, on the subject of leak-before-break in nuclear reactor piping systems. The purpose of the meeting was to provide an international forum for the exchange of ideas, positions, and research results; to identify areas requiring additional research and development; and to determine the general attitude toward acceptance of the leak-before-break concept. The importance of the leak-before-break issue was evidenced by excellent attendance at the meeting and through active participation by the meeting attendees. Approximately 125 people representing fifteen different nations attended the meeting. The meeting was divided into four technical sessions addressing the following areas: Application of Piping Fracture Mechanics to Leak-Before Break, Leak Rate and Leak Detection, Leak-Before-Break Studies, Methods and Results, Current and Proposed Positions on Leak-Before-Break.

CSNI specialist meeting on leak-before-break in nuclear reactor piping: proceedings

International Nuclear Information System (INIS)

1984-08-01

On September 1 and 2, 1983, the CSNI subcommittee on primary system integrity held a special meeting in Monterey, California, on the subject of leak-before-break in nuclear reactor piping systems. The purpose of the meeting was to provide an international forum for the exchange of ideas, positions, and research results; to identify areas requiring additional research and development; and to determine the general attitude toward acceptance of the leak-before-break concept. The importance of the leak-before-break issue was evidenced by excellent attendance at the meeting and through active participation by the meeting attendees. Approximately 125 people representing fifteen different nations attended the meeting. The meeting was divided into four technical sessions addressing the following areas: Application of Piping Fracture Mechanics to Leak-Before Break, Leak Rate and Leak Detection, Leak-Before-Break Studies, Methods and Results, Current and Proposed Positions on Leak-Before-Break

Surf similarity and solitary wave runup

DEFF Research Database (Denmark)

Fuhrman, David R.; Madsen, Per A.

2008-01-01

The notion of surf similarity in the runup of solitary waves is revisited. We show that the surf similarity parameter for solitary waves may be effectively reduced to the beach slope divided by the offshore wave height to depth ratio. This clarifies its physical interpretation relative to a previ...... functional dependence on their respective surf similarity parameters. Important equivalencies in the runup of sinusoidal and solitary waves are thus revealed.......The notion of surf similarity in the runup of solitary waves is revisited. We show that the surf similarity parameter for solitary waves may be effectively reduced to the beach slope divided by the offshore wave height to depth ratio. This clarifies its physical interpretation relative...... to a previous parameterization, which was not given in an explicit form. Good coherency with experimental (breaking) runup data is preserved with this simpler parameter. A recasting of analytical (nonbreaking) runup expressions for sinusoidal and solitary waves additionally shows that they contain identical...

Nilpotent chiral superfield in N=2 supergravity and partial rigid supersymmetry breaking

Energy Technology Data Exchange (ETDEWEB)

Kuzenko, Sergei M. [School of Physics M013, The University of Western Australia,35 Stirling Highway, Crawley W.A. 6009 (Australia); Tartaglino-Mazzucchelli, Gabriele [Instituut voor Theoretische Fysica, KU Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium)

2016-03-15

In the framework of N=2 conformal supergravity in four dimensions, we introduce a nilpotent chiral superfield suitable for the description of partial supersymmetry breaking in maximally supersymmetric spacetimes. As an application, we construct Maxwell-Goldstone multiplet actions for partial N=2→N=1 supersymmetry breaking on ℝ×S{sup 3}, AdS{sub 3}×S{sup 1} (or its covering AdS{sub 3}×ℝ), and a pp-wave spacetime. In each of these cases, the action coincides with a unique curved-superspace extension of the N=1 supersymmetric Born-Infeld action, which is singled out by the requirement of U(1) duality invariance.

Small break loss of coolant accidents: Bottom and side break

International Nuclear Information System (INIS)

Hardy, P.G.; Richter, H.J.

1987-01-01

A LOCA can be caused, e.g. by a small break in the primary cooling system. The rate of fluid escaping through such a break will define the time until the core will be uncovered. Therefore the prediction of fluid loss and pressure transient is of major importance to plan for timely action in response to such an event. Stratification of the two phases might be present upstream of the break, thus, the location of the break relative to the vapor-liquid interface and the overall upstream fluid conditions are relevant for the calculation of fluid loss. Experimental results and analyses are presented here for small breaks at the bottom or at the side of a small pressure vessel. It was found that in such a case the onset of the so-called ''vapor pull through'' is important but swelling at sufficient depressurization rates of the liquid due to flashing is also of significance. It was also discovered that in the bottom break the flow rate is strongly dependent on the break entrance quality of the vapour-liquid mixture. The side break can be treated similarly to the bottom break if the interface level is above the break. The analyses developed on the basis of experimental observations showed reasonable agreement of predicted and measured pressure transients. It was possible to calculate the changing interface level and mixture void fraction history in a way compatible with the behavior observed during the experiments. Even though the experiments were performed at low pressures, this work should help to get a better understanding of physical phenomena occurring in a full scale small break LOCA. (orig./HP)

Estimated yield of double-strand breaks from internal exposure to tritium.

Science.gov (United States)

Chen, Jing

2012-08-01

Internal exposure to tritium may result in DNA lesions. Of those, DNA double-strand breaks (DSBs) are believed to be important. However, experimental and computational data of DSBs induction by tritium are very limited. In this study, microdosimetric characteristics of uniformly distributed tritium were determined in dimensions of critical significance in DNA DSBs. Those characteristics were used to identify other particles comparable to tritium in terms of microscopic energy deposition. The yield of DSBs could be strongly dependent on biological systems and cellular environments. After reviewing theoretically predicted and experimentally determined DSB yields available in the literature for low-energy electrons and high-energy protons of comparable microdosimetric characteristics to tritium in the dimensions relevant to DSBs, it is estimated that the average DSB yields of 2.7 × 10(-11), 0.93 × 10(-11), 2.4 × 10(-11) and 1.6 × 10(-11) DSBs Gy(-1) Da(-1) could be reasonable estimates for tritium in plasmid DNAs, yeast cells, Chinese hamster V79 cells and human fibroblasts, respectively. If a biological system is not specified, the DSB yield from tritium exposure can be estimated as (2.3 ± 0.7) × 10(-11) DSBs Gy(-1) Da(-1), which is a simple average over experimentally determined yields of DSBs for low-energy electrons in various biological systems without considerations of variations caused by different techniques used and obvious differences among different biological systems where the DSB yield was measured.

Integrating Unified Gravity Wave Physics into the NOAA Next Generation Global Prediction System

Science.gov (United States)

Alpert, J. C.; Yudin, V.; Fuller-Rowell, T. J.; Akmaev, R. A.

2017-12-01

The Unified Gravity Wave Physics (UGWP) project for the Next Generation Global Prediction System (NGGPS) is a NOAA collaborative effort between the National Centers for Environmental Prediction (NCEP), Environemntal Modeling Center (EMC) and the University of Colorado, Cooperative Institute for Research in Environmental Sciences (CU-CIRES) to support upgrades and improvements of GW dynamics (resolved scales) and physics (sub-grid scales) in the NOAA Environmental Modeling System (NEMS)†. As envisioned the global climate, weather and space weather models of NEMS will substantially improve their predictions and forecasts with the resolution-sensitive (scale-aware) formulations planned under the UGWP framework for both orographic and non-stationary waves. In particular, the planned improvements for the Global Forecast System (GFS) model of NEMS are: calibration of model physics for higher vertical and horizontal resolution and an extended vertical range of simulations, upgrades to GW schemes, including the turbulent heating and eddy mixing due to wave dissipation and breaking, and representation of the internally-generated QBO. The main priority of the UGWP project is unified parameterization of orographic and non-orographic GW effects including momentum deposition in the middle atmosphere and turbulent heating and eddies due to wave dissipation and breaking. The latter effects are not currently represented in NOAA atmosphere models. The team has tested and evaluated four candidate GW solvers integrating the selected GW schemes into the NGGPS model. Our current work and planned activity is to implement the UGWP schemes in the first available GFS/FV3 (open FV3) configuration including adapted GFDL modification for sub-grid orography in GFS. Initial global model results will be shown for the operational and research GFS configuration for spectral and FV3 dynamical cores. †http://www.emc.ncep.noaa.gov/index.php?branch=NEMS

Blocking Radial Diffusion in a Double-Waved Hamiltonian Model

International Nuclear Information System (INIS)

Martins, Caroline G L; De Carvalho, R Egydio; Marcus, F A; Caldas, I L

2011-01-01

A non-twist Hamiltonian system perturbed by two waves with particular wave numbers can present Robust Tori, barriers created by the vanishing of the perturbing Hamiltonian at some defined positions. When Robust Tori exist, any trajectory in phase space passing close to them is blocked by emergent invariant curves that prevent the chaotic transport. We analyze the breaking up of the RT as well the transport dependence on the wave numbers and on the wave amplitudes. Moreover, we report the chaotic web formation in the phase space and how this pattern influences the transport.

Give me a better break: Choosing workday break activities to maximize resource recovery.

Science.gov (United States)

Hunter, Emily M; Wu, Cindy

2016-02-01

Surprisingly little research investigates employee breaks at work, and even less research provides prescriptive suggestions for better workday breaks in terms of when, where, and how break activities are most beneficial. Based on the effort-recovery model and using experience sampling methodology, we examined the characteristics of employee workday breaks with 95 employees across 5 workdays. In addition, we examined resources as a mediator between break characteristics and well-being. Multilevel analysis results indicated that activities that were preferred and earlier in the work shift related to more resource recovery following the break. We also found that resources mediated the influence of preferred break activities and time of break on health symptoms and that resource recovery benefited person-level outcomes of emotional exhaustion, job satisfaction, and organizational citizenship behavior. Finally, break length interacted with the number of breaks per day such that longer breaks and frequent short breaks were associated with more resources than infrequent short breaks. (c) 2016 APA, all rights reserved).

A break in the obesity epidemic?

DEFF Research Database (Denmark)

Visscher, T L S; Heitmann, B L; Rissanen, A

2015-01-01

Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look into the litera......, focusing on trends in waist circumference rather than BMI leads to a less optimistic conclusion: the public health problem of obesity is still increasing.International Journal of Obesity advance online publication, 22 July 2014; doi:10.1038/ijo.2014.98....... into the literature presented in recent reviews to address the major potential biases and distortions, and to develop insights about how to interpret the presented suggestions for a potential break in the obesity epidemic. Decreasing participation rates, the use of reported rather than measured data and small sample...

Report of 22nd International Symposium on Shock Waves; Dai 22 kai kokusai shogekiha symposium shusseki hokoku

Energy Technology Data Exchange (ETDEWEB)

Takayama, K. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science

1999-11-05

Outlined herein are the topics at the 22nd. International Symposium on Shock Waves, held in July 1999 in London. Prof. Takayama of Tohoku University gave an invited lecture on application of shock waves to medical area, stressing significance of shock waves on a human body. A total of 81 papers were presented from Japan. Number of Japanese papers and number of Japanese attendees both accounted for approximately 25%. The themes of these papers are centered by behavior of shock waves (e.g., propagation, reflection, and diffraction), extreme supersonic flows, interference between shock wave and boundary layer, aerodynamics (e.g., interference between vortex and shock wave), numerical simulation of shock wave phenomena, development of a new shock wave tube and measurement method, researches on elementary steps in chemical reactions, shock wave phenomena in condensed media and multi-phase media, shock wave noise produced while a high-speed train is running in a tunnel, and application of shock waves to industrial and medical areas. Japan contributes much to the application to medical area, and a method dispensing with injection is reported. Japan's aerospace-related researches include interference between shock wave and boundary layer, in which the real gas effect is taken into consideration, designs for protection from heat during the re-entry into the atmosphere, and construction of the world largest free-piston type wind tunnel. (NEDO)

Combustion, detonation, shock waves. Proceedings of the Zel'dovich memorial - International conference on combustion. Volume 1

International Nuclear Information System (INIS)

Merzhanov, A.G.; Frolov, S.M.

1995-01-01

This book contains lectures by the experts in various fields of modern research in combustion, detonation and shock waves, presented at the Zel'dovich memorial - International conference on combustion dedicated to the 80-th birthday of academician Ya.B. Zel'dovich. There are eight chapters discussing the state-of-the-art in combustion kinetics, ignition and steady-state flame propagation, diffusion and heterogeneous combustion, turbulent combustion, unsteady combustion, detonation, combustion and detonation analogies, intense shock waves and extreme states of matter [ru

Computation of nonlinear water waves with a high-order Boussinesq model

DEFF Research Database (Denmark)

Fuhrman, David R.; Madsen, Per A.; Bingham, Harry

2005-01-01

Computational highlights from a recently developed high-order Boussinesq model are shown. The model is capable of treating fully nonlinear waves (up to the breaking point) out to dimensionless depths of (wavenumber times depth) kh \\approx 25. Cases considered include the study of short......-crested waves in shallow/deep water, resulting in hexagonal/rectangular surface patterns; crescent waves, resulting from unstable perturbations of plane progressive waves; and highly-nonlinear wave-structure interactions. The emphasis is on physically demanding problems, and in eachcase qualitative and (when...

Effects of valence nucleon orbits and charge symmetry breaking interaction on the Nolen-Schiffer anomaly of mirror nuclei

International Nuclear Information System (INIS)

Suzuki, T.; Sagawa, H.; Arima, A.

1992-01-01

Coulomb energy differences (Nolen-Schiffer anomalies) of mirror nuclei 17 O- 17 F and 41 Ca- 41 Sc are studied by using realistic Hartree-Fock and Woods-Saxon single-particle wave functions which are determined precisely through the analysis of the magnetic form factors of electron scattering. These single-particle wave functions are used to evaluate the Coulomb energy differences due to charge symmetry breaking forces, with new coupling constants determined by the analysis of the scattering lengths of pp and nn system which have been successfully applied to the Coulomb energy difference of 3 He- 3 H. We also evaluated the effects of the charge symmetry breaking forces using Hartree-Fock wave functions. Together with various other contributions, our calculated values of the Coulomb energy differences, which showed deviations of 3-9% from the experimental values in the previous analysis of Nolen and Schiffer, agree with the experimental values within 1% (2%) accuracy for A=17 (41). (orig.)

Determining the degree of break up of coal strata and clay interlayers by looseners at the Chukurovo pit

Energy Technology Data Exchange (ETDEWEB)

Atanasov, A B; Stoyanov, D S; Yordanov, Y M

1983-01-01

One of the rational technologies for selective mining of thin coal strata with complex geological structure is that one in which different types of mechanical looseners are used. Identification of the degree of break up of the rock is accomplished most rapidly and precisely using seismoacoustical methods. The evaluation is conducted relative to the speed of propagation of elastic waves in the mass. SVM seismic receivers were used at the Chukurovo pit to determine the speed of propagation of an elastic wave in coals and clays. Shafts 10 meters long were drilled in three experimental fields using the SVB-2 machine. The speed of propagation of an elastic wave in the coals and in sandy clays was determined for different shaft depths every meter. After comparing the obtained results with standard tables from different companies, the possibility of breaking up the coal and clay interlayers in the experimental sectors by looseners with motors different in type and capacity was determined.

Propagation of internal gravity waves in the inhomogeneous atmosphere

International Nuclear Information System (INIS)

Deminov, M.G.; Ponomareva, L.I.

1988-01-01

Equations for disturbances of the density, temperature and speed of large-scale horizontally propagating internal gravity wave (IGM) wind are presented with regard to non-linearity, dispersion, molecular viscosity, thermal conductivity and background horizontal density and wind speed gradients. It is shown that values of wind speed and background atmosphere density decrease, typical of night conditions, provide for IGV amplitude increase near 250 km above the equator about 1.5 times, which with regard to the both hemispheres, fully compensates the effect of viscosity and thermal conductivity under increased solar activity. Speed and density decrease along IGW propagation can be provided both by background distribution of thermosphere parameters and by the front of a large-scale IGW on the background of which isolated IGW amplitude can grow

The solution of the dam-break problem in the Porous Shallow water Equations

Science.gov (United States)

Cozzolino, Luca; Pepe, Veronica; Cimorelli, Luigi; D'Aniello, Andrea; Della Morte, Renata; Pianese, Domenico

2018-04-01

The Porous Shallow water Equations are commonly used to evaluate the propagation of flooding waves in the urban environment. These equations may exhibit not only classic shocks, rarefactions, and contact discontinuities, as in the ordinary two-dimensional Shallow water Equations, but also special discontinuities at abrupt porosity jumps. In this paper, an appropriate parameterization of the stationary weak solutions of one-dimensional Porous Shallow water Equations supplies the inner structure of the porosity jumps. The exact solution of the corresponding dam-break problem is presented, and six different wave configurations are individuated, proving that the solution exists and it is unique for given initial conditions and geometric characteristics. These results can be used as a benchmark in order to validate one- and two-dimensional numerical models for the solution of the Porous Shallow water Equations. In addition, it is presented a novel Finite Volume scheme where the porosity jumps are taken into account by means of a variables reconstruction approach. The dam-break results supplied by this numerical scheme are compared with the exact dam-break results, showing the promising capabilities of this numerical approach. Finally, the advantages of the novel porosity jump definition are shown by comparison with other definitions available in the literature, demonstrating its advantages, and the issues raising in real world applications are discussed.

From hybrid to quadratic inflation with high-scale supersymmetry breaking

Directory of Open Access Journals (Sweden)

Constantinos Pallis

2014-09-01

Full Text Available Motivated by the reported discovery of inflationary gravity waves by the Bicep2 experiment, we propose an inflationary scenario in supergravity, based on the standard superpotential used in hybrid inflation. The new model yields a tensor-to-scalar ratio r≃0.14 and scalar spectral index ns≃0.964, corresponding to quadratic (chaotic inflation. The important new ingredients are the high-scale, (1.6–10⋅1013 GeV, soft supersymmetry breaking mass for the gauge singlet inflaton field and a shift symmetry imposed on the Kähler potential. The end of inflation is accompanied, as in the earlier hybrid inflation models, by the breaking of a gauge symmetry at (1.2–7.1⋅1016 GeV, comparable to the grand-unification scale.

Run-up of tsunamis and long waves in terms of surf-similarity

DEFF Research Database (Denmark)

Madsen, Per A.; Fuhrman, David R.

2008-01-01

of the surf-similarity parameter and the amplitude to depth ratio determined at some offshore location. We use the analytical expressions to analyze the impact of tsunamis on beaches and relate the discussion to the recent Indian Ocean tsunami from December 26, 2004. An important conclusion is that extreme...... run-up combined with extreme flow velocities occurs for surf-similarity parameters of the order 3-6, and for typical tsunami wave periods this requires relatively mild beach slopes. Next, we compare the theoretical solutions to measured run-up of breaking and non-breaking irregular waves on steep...

Investigation of the Effects of Ship Induced Waves on the Littoral Zone with Field Measurements and CFD Modeling

Directory of Open Access Journals (Sweden)

Gábor Fleit

2016-07-01

Full Text Available Waves induced by ship movement might be harmful for the habitat in the littoral zone of rivers due to the temporally increasing bed shear stress, the high-energy breaking waves and the consequently related detachment of benthic animals. In order to understand the complex hydrodynamic phenomena resulting from littoral waves, we present the testing of a novel methodology that incorporates field observations and numerical tools. The study is performed at a section of the Danube River in Hungary and analyzes the influence of different ship types. The field methods consist of parallel acoustic measurements (using Acoustic Doppler Velocimetry (ADV conducted at the riverbed and Large Scale Particle Image Velocimetry (LSPIV of the water surface. ADV measurements provided near-bed flow velocities based on which the wave induced currents and local bed shear stress could be estimated. The LSPIV was able to quantify the dynamics of the breaking waves along the bank. Furthermore, computational fluid dynamics (CFD modeling was successfully applied to simulate the propagation and the breaking of littoral waves. The used techniques complement each other well and their joint application provides an adequate tool to support the improvement of riverine habitats.

International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation

DEFF Research Database (Denmark)

Wendt, Fabian F.; Yu, Yi-Hsiang; Nielsen, Kim

2017-01-01

This is the first joint reference paper for the Ocean Energy Systems (OES) Task 10 Wave Energy Converter modeling verification and validation group. The group is established under the OES Energy Technology Network program under the International Energy Agency. OES was founded in 2001 and Task 10 ...

Coulomb versus nuclear break-up of 11Be halo nucleus in a non perturbative framework

International Nuclear Information System (INIS)

Fallot, M.; Scarpaci, J.A.; Margueron, J.; Lacroix, D.; Chomaz, Ph.

2000-01-01

The 11 Be break-up is calculated using a non perturbative time-dependent quantum calculation. The evolution of the neutron halo wave function shows an emission of neutron at large angles for grazing impact parameters and at forward angles for large impact parameters. The neutron angular distribution is deduced for the different targets and compared to experimental data. We emphasize the diversity of diffraction mechanisms, in particular we discuss the interplay of the nuclear effects such as the towing mode and the Coulomb break-up. A good agreement is found with experimental data. (authors)

Numerical investigation of freak waves

Science.gov (United States)

Chalikov, D.

2009-04-01

Paper describes the results of more than 4,000 long-term (up to thousands of peak-wave periods) numerical simulations of nonlinear gravity surface waves performed for investigation of properties and estimation of statistics of extreme (‘freak') waves. The method of solution of 2-D potential wave's equations based on conformal mapping is applied to the simulation of wave behavior assigned by different initial conditions, defined by JONSWAP and Pierson-Moskowitz spectra. It is shown that nonlinear wave evolution sometimes results in appearance of very big waves. The shape of freak waves varies within a wide range: some of them are sharp-crested, others are asymmetric, with a strong forward inclination. Some of them can be very big, but not steep enough to create dangerous conditions for vessels (but not for fixed objects). Initial generation of extreme waves can occur merely as a result of group effects, but in some cases the largest wave suddenly starts to grow. The growth is followed sometimes by strong concentration of wave energy around a peak vertical. It is taking place in the course of a few peak wave periods. The process starts with an individual wave in a physical space without significant exchange of energy with surrounding waves. Sometimes, a crest-to-trough wave height can be as large as nearly three significant wave heights. On the average, only one third of all freak waves come to breaking, creating extreme conditions, however, if a wave height approaches the value of three significant wave heights, all of the freak waves break. The most surprising result was discovery that probability of non-dimensional freak waves (normalized by significant wave height) is actually independent of density of wave energy. It does not mean that statistics of extreme waves does not depend on wave energy. It just proves that normalization of wave heights by significant wave height is so effective, that statistics of non-dimensional extreme waves tends to be independent

High accuracy subwavelength distance measurements: A variable-angle standing-wave total-internal-reflection optical microscope

International Nuclear Information System (INIS)

Haynie, A.; Min, T.-J.; Luan, L.; Mu, W.; Ketterson, J. B.

2009-01-01

We describe an extension of the total-internal-reflection microscopy technique that permits direct in-plane distance measurements with high accuracy (<10 nm) over a wide range of separations. This high position accuracy arises from the creation of a standing evanescent wave and the ability to sweep the nodal positions (intensity minima of the standing wave) in a controlled manner via both the incident angle and the relative phase of the incoming laser beams. Some control over the vertical resolution is available through the ability to scan the incoming angle and with it the evanescent penetration depth.

Childhood physical maltreatment, perceived social isolation, and internalizing symptoms: a longitudinal, three-wave, population-based study.

Science.gov (United States)

Sheikh, Mashhood Ahmed

2018-04-01

A number of cross-sectional studies have consistently shown a correlation between childhood physical maltreatment, perceived social isolation and internalizing symptoms. Using a longitudinal, three-wave design, this study sought to assess the mediating role of perceived social isolation in adulthood in the association between childhood physical maltreatment and internalizing symptoms in adulthood. The study has a three-wave design. We used data collected from 1994 to 2008 within the framework of the Tromsø Study (N = 4530), a representative prospective cohort study of men and women. Perceived social isolation was measured at a mean age of 54.7 years, and internalizing symptoms were measured at a mean age of 61.7 years. The difference-in-coefficients method was used to assess the indirect effects and the proportion (%) of mediated effects. Childhood physical maltreatment was associated with an up to 68% [relative risk (RR) = 1.68, 95% confidence interval (CI): 1.33-2.13] higher risk of perceived social isolation in adulthood. Childhood physical maltreatment and perceived social isolation in adulthood were associated with greater levels of internalizing symptoms in adulthood (p social isolation in adulthood mediated up to 14.89% (p social isolation into account when considering the impact of childhood physical maltreatment on internalizing symptoms.

Massachusetts Bay - Internal wave packets digitized from SAR imagery and intersected with a bathymetrically derived slope surface

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with a bathymetrically derived slope surface for Massachusetts Bay. The...

The 14th international workshop on wave hindcasting and forecasting and the 5th coastal hazards symposium

Science.gov (United States)

Breivik, Øyvind; Alves, Jose Henrique; Greenslade, Diana; Horsburgh, Kevin; Swail, Val

2017-04-01

Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice.

Simulations and observation of nonlinear internal waves on the continental shelf: Korteweg–de Vries and extended Korteweg–de Vries solutions

Directory of Open Access Journals (Sweden)

K. O'Driscoll

2017-09-01

Full Text Available Numerical solutions of the Korteweg–de Vries (KdV and extended Korteweg–de Vries (eKdV equations are used to model the transformation of a sinusoidal internal tide as it propagates across the continental shelf. The ocean is idealized as being a two-layer fluid, justified by the fact that most of the oceanic internal wave signal is contained in the gravest mode. The model accounts for nonlinear and dispersive effects but neglects friction, rotation and mean shear. The KdV model is run for a number of idealized stratifications and unique realistic topographies to study the role of the nonlinear and dispersive effects. In all model solutions the internal tide steepens forming a sharp front from which a packet of nonlinear solitary-like waves evolve. Comparisons between KdV and eKdV solutions are made. The model results for realistic topography and stratification are compared with observations made at moorings off Massachusetts in the Middle Atlantic Bight. Some features of the observations compare well with the model. The leading face of the internal tide steepens to form a shock-like front, while nonlinear high-frequency waves evolve shortly after the appearance of the jump. Although not rank ordered, the wave of maximum amplitude is always close to the jump. Some features of the observations are not found in the model. Nonlinear waves can be very widely spaced and persist over a tidal period.

Non-ideal dust acoustic waves

International Nuclear Information System (INIS)

Konefka, F; Contreras, J P; Puerta, J; Castro, E; MartIn, P

2008-01-01

The dispersion relation for dust acoustic waves (DA waves) functionally depends on the state equation for the charged dust grains. The ideal gas equation is usually used for studying the effect of temperature on this dispersion relation. However, since the space occupied by the grains can be important in high-density plasmas, the non-ideal effects can be important in this case. This paper analyses the dispersion relation for DA waves, when more precise state equations are used as those described for Pade approximants. The correction to the usual wave equation has been determined and the break point in density, where the ideal gas-state equation has been found. The non-ideal effects are more important for short wavelength ones, and the limits where those effects become important are also studied. Since there are several experimental results for these kinds of waves, the importance of the non-ideal effects in these cases is analysed in detail.

Investigation of the relationship between hurricane waves and extreme runup

Science.gov (United States)

Thompson, D. M.; Stockdon, H. F.

2006-12-01

In addition to storm surge, the elevation of wave-induced runup plays a significant role in forcing geomorphic change during extreme storms. Empirical formulations for extreme runup, defined as the 2% exceedence level, are dependent on some measure of significant offshore wave height. Accurate prediction of extreme runup, particularly during hurricanes when wave heights are large, depends on selecting the most appropriate measure of wave height that provides energy to the nearshore system. Using measurements from deep-water wave buoys results in an overprediction of runup elevation. Under storm forcing these large waves dissipate across the shelf through friction, whitecapping and depth-limited breaking before reaching the beach and forcing swash processes. The use of a local, shallow water wave height has been shown to provide a more accurate estimate of extreme runup elevation (Stockdon, et. al. 2006); however, a specific definition of this local wave height has yet to be defined. Using observations of nearshore waves from the U.S. Army Corps of Engineers' Field Research Facility (FRF) in Duck, NC during Hurricane Isabel, the most relevant measure of wave height for use in empirical runup parameterizations was examined. Spatial and temporal variability of the hurricane wave field, which made landfall on September 18, 2003, were modeled using SWAN. Comparisons with wave data from FRF gages and deep-water buoys operated by NOAA's National Data Buoy Center were used for model calibration. Various measures of local wave height (breaking, dissipation-based, etc.) were extracted from the model domain and used as input to the runup parameterizations. Video based observations of runup collected at the FRF during the storm were used to ground truth modeled values. Assessment of the most appropriate measure of wave height can be extended over a large area through comparisons to observations of storm- induced geomorphic change.

SPIN-PRECESSION: BREAKING THE BLACK HOLE-NEUTRON STAR DEGENERACY

Energy Technology Data Exchange (ETDEWEB)

Chatziioannou, Katerina; Cornish, Neil; Klein, Antoine; Yunes, Nicolás [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2015-01-01

Mergers of compact stellar remnants are prime targets for the LIGO/Virgo gravitational wave detectors. The gravitational wave signals from these merger events can be used to study the mass and spin distribution of stellar remnants, and provide information about black hole horizons and the material properties of neutron stars. However, it has been suggested that degeneracies in the way that the star's mass and spin are imprinted in the waveforms may make it impossible to distinguish between black holes and neutron stars. Here we show that the precession of the orbital plane due to spin-orbit coupling breaks the mass-spin degeneracy, and allows us to distinguish between standard neutron stars and alternative possibilities, such as black holes or exotic neutron stars with large masses and spins.

Wind and waves in extreme hurricanes

NARCIS (Netherlands)

Holthuijsen, L.H.; Powell, M.D.; Pietrzak, J.D.

2012-01-01

Waves breaking at the ocean surface are important to the dynamical, chemical and biological processes at the air-sea interface. The traditional view is that the white capping and aero-dynamical surface roughness increase with wind speed up to a limiting value. This view is fundamental to hurricane

The interaction of katabatic winds and mountain waves

Energy Technology Data Exchange (ETDEWEB)

Poulos, Gregory Steve [Colorado State Univ., Fort Collins, CO (United States)

1997-01-01

The variation in the oft-observed, thermally-forced, nocturnal katabatic winds along the east side of the Rocky Mountains can be explained by either internal variability or interactions with various other forcings. Though generally katabatic flows have been studied as an entity protected from external forcing by strong thermal stratification, this work investigates how drainage winds along the Colorado Front Range interact with, in particular, topographically forced mountain waves. Previous work has shown, based on measurements taken during the Atmospheric Studies in Complex Terrain 1993 field program, that the actual dispersion in katabatic flows is often greater than reflected in models of dispersion. The interaction of these phenomena is complicated and non-linear since the amplitude, wavelength and vertical structure of mountain waves developed by flow over the Rocky Mountain barrier are themselves partly determined by the evolving atmospheric stability in which the drainage flows develop. Perturbations to katabatic flow by mountain waves, relative to their more steady form in quiescent conditions, are found to be caused by both turbulence and dynamic pressure effects. The effect of turbulent interaction is to create changes to katabatic now depth, katabatic flow speed, katabatic jet height and, vertical thermal stratification. The pressure effect is found to primarily influence the variability of a given katabatic now through the evolution of integrated column wave forcing on surface pressure. Variability is found to occur on two scales, on the mesoscale due to meso-gamma scale mountain wave evolution, and on the microscale, due to wave breaking. Since existing parameterizations for the statically stable case are predominantly based on nearly flat terrain atmospheric measurements under idealized or nearly quiescent conditions, it is no surprise that these parameterizations often contribute to errors in prediction, particularly in complex terrain.

Dual realizations of dynamical symmetry breaking

International Nuclear Information System (INIS)

Dudas, Emilian; Papineau, Chloe

2006-01-01

We show the infrared equivalence between a recently proposed model containing a six dimensional scalar field with a four-dimensional localized Higgs type potential and the four-dimensional Nambu-Jona-Lasinio (NJL) model. In the dual NJL description, the fermions are localized at the origin of a large two-dimensional compact space. Due to a classical running effect above the compactification scale, the four-fermion coupling of the NJL model increases from the cutoff scale down to the compactification scale, providing the large Fermi coupling needed for the dynamical symmetry breaking. We also present a string theory embedding of our field-theory construction. On more general grounds, our results suggest that 4d models with dynamical symmetry breaking can be given a higher dimensional description in terms of field theories with nontrivial boundary conditions in the internal space

Induction of DNA strand breaks in 14C-labelled cells

International Nuclear Information System (INIS)

Sundell-Bergman, S.; Johanson, K.J.

1979-01-01

Chinese hamster cells grown in vitro were labelled with 14 C-thymidine for 18 hours and after 3 hours in non-radioactive medium they were stored at 0 0 C for various periods ( 1 to 12 hours). During this treatment a number of DNA strand breaks were induced by 14 C decay which were not repaired at 0 0 C. The number of DNA strand breaks was determined using the DNA unwinding technique. At 0.5-1 dpm per cell a detectable number of DNA strand breaks were found. Treatment for six hours (1 dpm per cell) reduced the percentage of double-stranded DNA from 80 to 70%, corresponding to about 750 DNA strand breaks per cell. The rejoining of DNA strand breaks was studied after treatment for 12 hours at 0 0 C followed by incubation of the cells for various periods at 37 0 C. Most of the DNA strand breaks induced by 14 C decay at 0 0 C were repaired after incubation at 37 0 C for 15 minutes. Assuming an absorbed dose of 1.8 mGy per 14 C decay to the cell nucleus an RBE value close to 1 was found for internal irradiation from 14 C decay as compared with 60 Co-gamma irradiation. (author)