Dissertations / Theses on the topic 'Surface gravity wave'
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Thomas, Alexandra Elizabeth. "The interaction of an internal solitary wave with surface gravity waves." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/13106.
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Solitary waves are nonlinear, non-oscillatory disturbances of permanent form. Recent advances in synthetic aperture radar imaging and analysis techniques have confirmed in situ observations and measurements that the passage of oceanic internal waves, and in particular internal solitary waves, is associated with modulations in sea surface roughness. It has not only revealed the ubiquity of this phenomenon but also highlighted the global existence of large amplitude, tidally induced, internal solitary waves. It appears, however, that little laboratory-based research has been carried out in this field. This work, therefore, focusses on the study of surface wavetrain modulations resulting from the passage of a single internal solitary wave. Digital Particle Image Velocimetry (DPIV) and Planar Laser Induced Fluorescence (PLIF) were employed to provide two-dimensional instantaneous velocity and density information respectively. Previous studies in this field have been performed with intrusive probe techniques, disturbing the fluid flow during measurement. Preliminary DPIV and PLIF experiments were performed on single internal solitary waves in a two-layer brine - fresh water stratification. To the author’s knowledge, the application of PLIF to the study of these waves had not been done previously. Results from the DPIV measurements concurred with previous research and highlighted the constraints of the DPIV system. The results were also compared to a recently developed and validated fully nonlinear numerical method. From the interaction investigations, both wavelength and amplitude modulations of the surface waves as a function of solitary wave phase were observed. In some cases, the shape of the internal wave was also affected. Velocity profiles were compared to the linear superposition of surface wave linear theory and the fully nonlinear numerical method. In addition, the PLIF analysis showed that, for the wave and stratification parameters investigated, there was no evidence for the compression and expansion of the density interface during the interaction.
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Chamberlain, Neil. "Wave-induced mixing within a gravity-driven surface current." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325566.
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Howell, David W. "A numerical study of rain-induced surface gravity wave attenuation." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27173.
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van, den Bremer T. S. "The induced mean flow of surface, internal and interfacial gravity wave groups." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e735afe7-a77d-455d-a560-e869a9941f69.
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Although the leading-order motion of waves is periodic - in other words backwards and forwards - many types of waves including those driven by gravity induce a mean flow as a higher-order effect. It is the induced mean flow of three types of gravity waves that this thesis examines: surface (part I), internal (part II) and interfacial gravity waves (part III). In particular, this thesis examines wave groups. Because they transport energy, momentum and other tracers, wave-induced mean flows have important consequences for climate, environment, air traffic, fisheries, offshore oil and other industries. In this thesis perturbation methods are used to develop a simplified understanding of the physics of the induced mean flow for each of these three types of gravity wave groups. Leading-order estimates of different transport quantities are developed. For surface gravity wave groups (part I), the induced mean flow consists of two compo- nents: the Stokes drift dominant near the surface and the Eulerian return flow acting in the opposite direction and dominant at depth. By considering subsequent orders in a separation of scales expansion and by comparing to the Fourier-space solutions of Longuet-Higgins and Stewart (1962), this thesis shows that the effects of frequency dis- persion can be ignored for deep-water waves with realistic bandwidths. An approximate depth scale is developed and validated above which the Stokes drift is dominant and below which the return flow wins: the transition depth. Results are extended to include the effects of finite depth and directional spreading. Internal gravity wave groups (part II) do not display Stokes drift, but a quantity analogous to Stokes transport for surface gravity waves can still be developed, termed the “divergent- flux induced flow” herein. The divergent-flux induced flow it itself a divergent flow and induces a response. In a three-dimensional geometry, the divergent-flux induced flow and the return flow form a balanced circulation in the horizontal plane with the former transporting fluid through the centre of the group and the latter acting in the opposite direction around the group. In a two-dimensional geometry, stratification inhibits a balanced circulation and a second type of waves are generated that travel far ahead and in the lee of the wave group. The results in the seminal work of Bretherton (1969b) are thus validated, explicit expressions for the response and return flow are developed and compared to numerical simulations in the two-dimensional case. Finally, for interfacial wave groups (part III) the induced mean flow is shown to behave analogously to the surface wave problem of part I. Exploring both pure interfacial waves in a channel with a closed lid and interacting surface and interfacial waves, expressions for the Stokes drift and return flow are found for different configurations with the mean set-up or set-down of the interface playing an important role.
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Lin, Yiqiang Farouk Bakhtier. "Acoustic wave induced convection and transport in gases under normal and micro-gravity conditions /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1795.
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Yarber, Robert K. "Development and calibration of two and four wire water surface wave height measurement systems." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23863.
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Approved for public release; distribution is unlimitedCapacitance and conductance measurements using two and four wire techniques were developed and statically and dynamically calibrated in this thesis. The voltage sensitivities range from 7.3 to 8.1 ± 0.1 mV/cm for the two wire capacitance system static calibrations. This is ± 5.2% of the limiting theoretical value. The voltage sensitivities range from 0.3 to 0.4 ± 0.1 V/cm for the four wire conductance system static calibrations. Dynamic calibrations were only completed for the conductance system. The dynamic calibration results were weakly frequency dependent with a qj-0.15 decay in a limited, 2-4 Hz range. Wind power spectrum measurements were taken in the existing Upper Ocean Simulations Facility at the Naval Postgraduate School. There was excellent agreement in the spectra with both techniques. Driven gravity wave frequency downshifting and wind energy dumping was observed in the combined gravity wave and wind-wave measurements. The power spectra peaked near two Hertz and decayed at 50 to 70 dB per decade, or as CO -5 to G)" 7 for both systems. Gravity wave phase speed and wavelength measurements were performed with the capacitance system. The results were approximately 40% higher than theory.
http://archive.org/details/developmentcalib00yarb
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McAllister, Mark Laing. "Analysis of laboratory and field measurements of directionally spread nonlinear ocean waves." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28762.
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Surface gravity waves exist in the oceans as multi-directional nonlinear phenomena. Understanding how these two properties interact is intrinsically important in itself. Furthermore, an understanding of this relationship may be used to gain insight into other oceanic phenomena. This thesis first describes an experimental investigation into the relationship between directionality and non-linearity (Part I). This relationship was then used as a tool to estimate the directional spreading of field data (Part II). Experiments have been conducted in which directionally spread focused wave groups were created in a wave tank. The relationship between the degree of directional spreading and the second-order bound harmonics of the wave groups was examined, in particular the formation of a `set-up'. These measurements were then compared to predictions from second-order theories, finding good agreement. The two-dimensional structure of the bound waves was explored giving new insight into the underlying physics. Experiments were then carried out for directionally spread crossing wave groups. It is believed that the crossing of two sufficiently separated wave groups may be the cause of an anomalous set-up in the second-order bound waves observed for some extreme and potentially freak waves. This set-up is reproduced experimentally. Again, the results of these test agreed very well when compared to second-order theory. The insight gained from the foregoing experiments was then utilised in the analysis of field data. A method, which requires only a single measurement to estimate the observed degree of directional spreading, was applied to a large dataset of field measurements from the North Alwyn platform in the North Sea. This method was then compared to conventional approaches, which require multiple concurrent measurements. The method that requires only a single measurement was shown to be effective, and presents a promising approach to gaining additional insight about the directional spreading of point observations.
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Parmhed, Oskar. "Near surface atmospheric flow over high latitude glaciers." Doctoral thesis, Stockholm University, Department of Meteorology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-197.
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In this thesis various descriptions of the near surface atmospheric flow over a high latitude glacier is used in an effort to increase our understanding of the basic flow dynamics there.
Through their contribution to sea-level change, mountain glaciers play a significant role in Earth’s climate system. Properties of the near surface atmospheric flow are important for understanding glacier response to climate change.
Here, the near surface atmospheric flow is studied from several perspectives including the effects of both rotation and slope. Rotation is an important aspect of most atmospheric flows and its significance for mesoscale flows have gained recognition over the last years. Similarly, the very stable boundary layer (VSBL) has lately gained interest. Within a VSBL over sloping terrain katabatic flow is known to be usual and persistent. For the present thesis a combination of numerical and simple analytical models as well as observations from the Vatnajökull glacier on Iceland have been used. The models have continuously been compared to available observations. Three different approaches have been used: linear wave modeling, analytic modeling of katabatic flow and of the Ekman layer, and numerical simulations of the katabatic flow using a state of the art mesoscale model. The analytic models for the katabatic flow and the Ekman layer used in this thesis both utilizes the WKB method to allow the eddy diffusivity to vary with height. This considerably improves the results of the models. Among other findings it is concluded that: a large part of the flow can be explained by linear theory, that good results can be obtained for surface energy flux using simple models, and that the very simple analytic models for the katabatic flow and the Ekman layer can perform adequately if the restraint of constant eddy diffusivity is relieved.
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Kupčíková, Laura. "Částice plovoucí na volné hladině vln." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444637.
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This master’s thesis deals with analytical and numerical description of surface gravity waves. Wave theories and their influence on water particle movement is described in the theoretical part of the thesis. Water particle moves in the same direction as wave propagation and this phenomenon is called Stokes drift. It has a significant influence on sediment transport and floating particle movement at water free surface. The experimental part consists of wave profile monitoring and water particle tracking in a wave flume with wave generator and beach model. The experimental results are compared with numerical simulation performed in the ANSYS Fluent software. Finally, the wave profiles obtained from simulation are compared with experimental wave profiles extracted by digital image processing.
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Chapalain, Georges. "Étude hydrodynamique et sédimentaire des environnements littoraux dominés par la houle." Université Joseph Fourier (Grenoble ; 1971-2015), 1988. http://www.theses.fr/1988GRE10121.
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La propagation des houles longues est étudiée expérimentalement, théoriquement et numériquement. La validité du modèle harmonique quasi-résonnant de lau et barcilon (1972) est confirmée. Les processus hydro-sédimentaires se développant dans la couche limite turbulente de fond générée par la houle sont analysés à l'aide d'un modèle uni-dimensionnel avec fermeture turbulente au second ordre. Un modèle simplifie avec fermeture turbulente au premier ordre est envisagé dans la perspective d'une modélisation des interactions des trains de houle avec un fond sableux. La modélisation hydro-morphologique ainsi élaborée explique la formation des barres sableuses d'avant-cote. Elle est confrontée avec succès à des mesures effectuées dans le lac Huron et dans le golfe du Saint-Laurent. L'extension de la modélisation a des substrats de granulométrie étendue est réalisée en vue de la simulation du tri granulométrique observe sur les systèmes de barres littorales. Enfin, un essai d'intégration des pertes d'énergie par les déferlements multiples survenant sur les séquences de barres est entrepris.
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Guibourg, Sandrine. "MModélisations numérique et expérimentale des houles bidimensionnelles en zone cotière." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10160.
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Une analyse theorique detaillee des equations de boussinesq et de serre a ete realisee. Les domaines de validite de chaque equation ont ete determines theoriquement. Ces equations d'ondes longues sont discretisees selon un schema aux differences finies pour des ondes de surface libre sur fond plat et fond variable. Par le biais d'une comparaison numerique avec des essais experimentaux d'ondes longues sur fond plat, les modeles numeriques ont ete etendus a la description des ondes courtes. Un terme dispersif correctif a ete introduit pour ameliorer les capacites dispersives des modeles. Des essais numeriques de propagation d'ondes longues sur un talus ont egalement ete compares aux experiences. Une etude de l'interaction d'une houle courte de haute frequence avec une onde solitaire nous a conduit a mesurer le dephasage que subit l'onde courte apres le passage du soliton. Nous nous sommes consacres a la validation experimentale d'une comparaison entre les modeles de boussinesq et de serre sur des plages peu inclinees, ainsi qu'a l'evolution du nombre d'ursell le long de la plage. L'etude experimentale a ensuite ete etendue aux phenomenes de run up, de run down et aux calculs des coefficients de reflexion des plages etudiees. Pour calculer numeriquement les run up, nous avons ameliore le modele de serre par des conditions de trait de cote variable
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Wu, Lichuan. "Introducing Surface Gravity Waves into Earth System Models." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-314760.
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Surface gravity waves alter the turbulence of the bottom atmosphere and the upper ocean. Accordingly, they can affect momentum flux, heat fluxes, gas exchange and atmospheric mixing. However, in most state-of-the-art Earth System Models (ESMs), surface wave influences are not fully considered or even included. Here, applying surface wave influences into ESMs is investigated from different aspects. Tuning parameterisations for including instantaneous wave influences has difficulties to capture wave influences. Increasing the horizontal resolution of models intensifies storm simulations for both atmosphere-wave coupled (considering the influence of instantaneous wave-induced stress) and stand-alone atmospheric models. However, coupled models are more sensitive to the horizontal resolution than stand-alone atmospheric models. Under high winds, wave states have a big impact on the sea spray generation. Introducing a wave-state-dependent sea spray generation function and Charnock coefficient into a wind stress parameterisation improves the model performance concerning wind speed (intensifies storms). Adding sea spray impact on heat fluxes improves the simulation results of air temperature. Adding sea spray impact both on the wind stress and heat fluxes results in better model performance on wind speed and air temperature while compared to adding only one wave influence. Swell impact on atmospheric turbulence closure schemes should be taken into account through three terms: the atmospheric mixing length scale, the swell-induced momentum flux at the surface, and the profile of swell-induced momentum flux. Introducing the swell impact on the three terms into turbulence closure schemes shows a better performance than introducing only one of the influences. Considering all surface wave impacts on the upper-ocean turbulence (wave breaking, Stokes drift interaction with the Coriolis force, Langmuir circulation, and stirring by non-breaking waves), rather than just one effect, significantly improves model performance. The non-breaking-wave-induced mixing and Langmuir circulation are the most important terms when considering the impact of waves on upper-ocean mixing. Accurate climate simulations from ESMs are very important references for social and biological systems to adapt the climate change. Comparing simulation results with measurements shows that adding surface wave influences improves model performance. Thus, an accurate description of all important wave impact processes should be correctly represented in ESMs, which are important tools to describe climate and weather. Reducing the uncertainties of simulation results from ESMs through introducing surface gravity wave influences is necessary.
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Law, Owen Yi Kei. "Experiments on evolution of surface gravity waves from deep to shallow waters /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?MECH%202004%20LAW.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 57-59). Also available in electronic version. Access restricted to campus users.
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Barros, Ricardo. "Gravity waves in two-layer flows with free surface." Aix-Marseille 3, 2007. http://www.theses.fr/2007AIX30080.
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Nous étudions dans cette thèse la propagation des ondes dans un écoulement à deux couches et à surface libre. Deux classes de modèles sont considérées. Nous nous consacrons d'abord à la version à deux-couches du modèle de Saint-Venant. Ce modèle est strictement hyperbolique pour des faibles vitesses relatives. Il serait naturel de considérer ce système d'équations pour la description des sauts hydrauliques. Il s'avère que, comme pour la plupart des modèles décrivant des systèmes multi-vitesses, les équations ne sont pas présentées sous forme conservative. C'est pourquoi on a réalisé une étude sur le nombre de lois de conservation pour le système qui semble indiquer que celui-ci est en fait non-conservatif. Comme conséquence, on a l'impossibilité de présenter un ensemble complet de conditions de Rankine-Hugoniot permettant ainsi la caractérisation des solutions faibles dans le sens classique. Nous obtenons ensuite un modèle dispersif adapté à la description de la propagation des ondes de grande amplitude pour le même système physique. Ce modèle est une généralisation naturelle du modèle de Green-Naghdi et sa dérivation est basée sur le principe d'Hamilton. L'idée conduisant au résultat consiste en l'obtention d'un Lagrangien pour le modèle approché en introduisant directement les approximations dans le Lagrangien du modèle complet. Par conséquent, la structure variationnelle ainsi que les propriétés de symétrie correspondantes sont préservées. De plus, aucune restriction du type ondes de faible amplitude ou écoulement potentiel n'est ici considéré. Comme dans le cas des équations d'Euler complètes, ce modèle reproduit la résonance entre les ondes courtes et les ondes longues. Dans ce cadre on montre, par des calculs numériques, l'existence de trajectoires homoclines qui correspondent aux vraies ondes solitaires ayant les mêmes vitesses à l'infini dans chaque couche. L'étude de ces ondes se réduit à l'étude d'un système Hamiltonien à deux degrés de liberté. Les ondes progressives dépendent de trois paramètres: le rapport de densité des fluides, le rapport des épaisseurs de chaque couche et le nombre de Froude. Deux régimes caractérisés par l'élévation ou la dépression de l'interface entre deux couches sont présentés. Le rapport critique des épaisseurs des couches sépare ces deux régimes et il sera montré comment le relier aux changements de la structure pour le potentiel du système Hamiltonien. L'analyse du nombre et la nature des points d'équilibre se sont montrés décisives pour établir le résultat. On a constaté que leur nombre ne peut être que de quatre ou de deux, selon la vitesse de ces ondes (pour un rapport de densité des fluides et un rapport des épaisseurs fixés). Pour les paramètres qui correspondent aux conditions océaniques, on a observé l'existence des ondes solitaires et leur élargissement ("broadening") lorsque la vitesse de ces ondes tend vers une certaine valeur limite. Enfin nous considérons différents paramètres pour lesquelles des solutions avec plusieurs bosses ( "multi-humped shaped profile") existent, illustrant la richesse et la complexité du système considéréIn this work we study the wave propagation in two-layer flows with free surface. Two distinct classes of models are contemplated. First, we consider the "two-layer" version of the shallow water equations (also known by Saint-Venant's equations). This model is strictly hyperbolic for small relative velocities. It would be natural to consider this model as suitable for the description of hydraulic jumps. However, like most of models describing multi-velocity flows, the system is not presented in conservative form. We present a survey on the number of conservation laws available for the multi-dimensional case that seems to imply that the system is truly nonconservative. Therefore, the impossibility of presenting a complete set of Rankine-Hugoniot conditions enabling the characterization of weak solutions in the classical way. Then, we obtain a dispersive model suited to the description of large amplitude waves propagating in the same physical system. The model is a "two-layer" generalization of the Green-Naghdi model and can be derived by applying Hamilton's principle to a Lagrangian that results from the insertion of approximations directly into the Lagrangian for the full waterwave problem. As a consequence, the variational structure of the original problem and the corresponding symmetry properties are preserved. In addition, it is a fully nonlinear model and deals with rotational flows. As in the case of the full problem, the present model captures the resonance between short waves and long waves. In this framework it is shown, by using numerical computations, the existence of homoclinic trajectories embedded into the continuous spectrum. These correspond to true solitary waves having the same velocities at infinity in each layer. Their study reduces to the analysis of a Hamiltonian system with two degrees of freedom. The traveling-wave solutions depend on three parameters : the density ratio, the depth ratio and the Froude number based on the bottom layer. Two wave regimes, characterized by the elevation or depression of the interface between the layers are presented. A critical depth ratio separates these two regimes and it will be shown how it relates to a change of the structure of the potential for the Hamiltonian system. The analysis of the number and nature of critical points turned out to be decisive in this work. It was found that the number of critical points can be four or two, depending on the value of the Froude number (for fixed density and depth ratios). For sets of parameters corresponding to oceanic conditions we have perceived the existence of true solitary waves and their broadening whenever the wave speed increases towards a limit value. Finally, other sets of parameters are considered for which multi-humped solitons exist, highlighting the richness and complexity of the system considered
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Aubourg, Quentin. "Étude expérimentale de la turbulence d’ondes à la surface d’un fluide. La théorie de la turbulence faible à l’épreuve de la réalité pour les ondes de capillarité et gravité." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI061/document.
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La turbulence d’onde cherche à apporter une description statistique des interactions d’un ensemble d’ondes faiblement non-linéaires. Initiée dans les années 1960 par les travaux de Zakharov et de Hasselmann, cette théorie est régulièrement mise en défaut par les observations expérimentales, en particulier dans le régime d’ondes de gravité ainsi qu’aux abords de la transition gravito-capillaire. L’objectif de cette thèse est d’étudier expérimentalement ces deux régimes en analysant directement les interactions résonantes qui sont le cœur de la théorie de la turbulence faible. Une première expérience concerne le régime gravito-capillaire. Une cascade d’énergie constituée d’ondes faiblement linéaires est observée en accord avec la phénoménologie de la turbulence faible. L’utilisation d’outils statistiques d’ordre supérieur a permis de montrer que ce sont des interactions à 3-ondes essentiellement colinéaires qui gouvernent la cascade. La seconde expérience explore le régime gravitaire dans la plateforme de Coriolis. Le spectre de puissance montre la présence systématique d’une branche harmonique qui reste faible devant la composante linéaire. Les corrélations indiquent la présence d’interactions à 3-ondes entre la branche linéaire et la branche harmonique. Aucune interaction à 4-ondes comme le prévoit la théorie n’est observée. La dernière partie rapporte les résultats d’une expérience sur des ondes internes ainsi qu’une campagne de mesure in-situ de la mer Noire dont les données ont été mises à disposition par F. Ardhuin. Ces deux expériences confirment les résultats de la partie précédente et soulèvent la question de l’importance des interactions à 3-ondes avec la branche harmonique pour la génération de la cascade en régime de gravité…The wave turbulence provides a statistical description of the interactions of a large set of weakly non-linear waves. Introduced in the 1960s by the works of Zakharov and Hasselmann, this theory often fails against experiments, particularly for gravity waves and at the crossover for capillary-gravity waves. The objective of this PhD is to study experimentally these two regimes by looking directly at the resonant interactions that are the heart of the weak turbulence theory. The first experiment focuses on the capillary-gravity regime. An energy cascade composed of weakly linear waves is observed in agreement with the phenomenology of the theory. The use of higher order statistical tools shows that it is essentially 3-waves collinear interaction that govern the cascade. The second experiment explores the pure gravity regime thanks to the large dimensions of the Coriolis platform. The full energy spectrum shows the systematic presence of the harmonic branch, although it remains small compared to the linear component. The correlations indicate the presence of strong 3-waves interactions between the linear branch and the harmonics branches. No 4-waves interaction as assumed by the theory is observed. The last section reports the results from an experiment on internal waves and from in situ data of the Black Sea made available by F. Ardhuin. These two experiments confirm the results of the previous section and raise the question of the importance of the 3-wave interaction with the harmonic branch for generating the energy cascade in the gravity wave regime…
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Masson, Diane. "Spectral evolution of wind generated surface gravity waves in a dispersed ice field." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/29020.
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The Marginal Ice Zone includes wide areas covered by dispersed ice floes in which wave conditions are significantly affected by the ice. When the wind blows from the solid ice pack, towards the open sea, growing waves are scattered by the floes, their spectral characteristics being modified. To further understand this problem, a model for the evolution of wind waves in a sparse field of ice floes was developed. The sea state is described by a two-dimensional discrete spectrum. Time-limited wave growth is obtained by numerical integration of the energy balance equation using the exact nonlinear transfer integral. Wave scattering by a single floe is represented in terms of far-field expressions of the diffracted and forced potentials obtained numerically by the Green's function method. The combined effect of a homogeneous field of floes on the wave spectrum is expressed in terms of the Foldy-Twersky integral equations under the assumption of single scattering. The results show a strong dependence of the spectrum amplitude and directional properties on the ratio of the ice floe diameter to the wavelength. For a certain range of this parameter, the ice cover appears to be very effective in dispersing the energy; the wave spectrum rapidly tends to isotropy, limiting its growth both for the energy content and the peak frequency. It is therefore unlikely that an offshore wind blowing over the Marginal Ice Zone would generate a significant wave field.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Wu, Lichuan. "Impact of surface gravity waves on air-sea fluxes and upper-ocean mixing." Licentiate thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-276466.
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Surface gravity waves play a vital role in the air-sea interaction. They can alter the turbulence ofthe bottom atmospheric layer as well as the upper-ocean layer. Accordingly, they can affect themomentum flux, heat fluxes, as well as the upper-ocean mixing. In most numerical models, waveinfluences are not considered or not fully considered. The wave influences on the atmosphereand the ocean are important for weather forecasts and climate studies. Here, different aspects ofwave impact on the atmosphere and the ocean are introduced into numerical models.In the first study, a wave-state-dependent sea spray generation function and Charnock co-efficient were applied to a wind stress parameterization under high wind speeds. The newlyproposed wind stress parameterization and a sea spray influenced heat flux parameterizationwere applied to an atmosphere-wave coupled model to study their influence on the simulationof mid-latitude storms. The new wind stress parameterization reduces wind speed simulationerror during high wind speed ranges and intensifies the storms. Adding the sea spray impacton heat fluxes improves the model performance concerning the air temperature. Adding the seaspray impact both on the wind stress and heat fluxes results in best model performance in allexperiments for wind speed, and air temperature.In the second study, the influence of surface waves on upper-ocean mixing was parameter-ized into a 1D k − ε ocean turbulence model though four processes (wave breaking, Stokes driftinteraction with the Coriolis force, Langmuir circulation, and stirring by non-breaking waves)based mainly on existing investigations. Considering all the effects of surface gravity waves,rather than just one effect, significantly improves model performance. The non-breaking-wave-induced mixing and Langmuir turbulence are the most important terms when considering theimpact of waves on upper-ocean mixing. Sensitivity experiments demonstrate that vertical pro-files of the Stokes drift calculated from 2D wave spectrum improve the model performancesignificantly compared with other methods of calculating the vertical profiles of the Stokes drift.Introducing the wave influences in modelling systems, the results verified against measure-ments. Concluding from these studies for the further model development, the wave influencesshould be taken into account to improve the model performance.
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Lawrence, Richard T. "Experimental inquires into collective sea state modes in deep water surface gravity waves." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23891.
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Gill, Patricia A. "An experimental study of collective sea state modes of deep water surface gravity waves." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA294007.
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Thesis (M.S. in Applied Physics) Naval Postgraduate School, December 1994.Thesis advisor(s): Robert Keolian, A. Larraza. "December 1994." DTIC Descriptor(s): Ocean Waves, Air Water Interactions, Sea States, Surface Waves, Ocean Surface, Wind, Theses, Turbulence, Wind Tunnel Tests, Wind Velocity, Spectral Energy Distribution, Amplitude, Deep Water, Height, Surface Tension, Phase Shift, Gravity Waves, Water Tanks. DTIC Identifier(s): Wind Waves, PE61153N. Bibliography: p. 51. Also available online.
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Shmelev, Alexey Alexandrovich. "Three-dimensional acoustic propagation through shallow water internal, surface gravity and bottom sediment waves." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69241.
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Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 185-193).
This thesis describes the physics of fully three-dimensional low frequency acoustic interaction with internal waves, bottom sediment waves and surface swell waves that are often observed in shallow waters and on continental slopes. A simple idealized model of the ocean waveguide is used to analytically study the properties of acoustic normal modes and their perturbations due to waves of each type. The combined approach of a semi-quantitative study based on the geometrical acoustics approximation and on fully three-dimensional coupled mode numerical modeling is used to examine the azimuthal dependence of sound wave horizontal reflection from, transmission through and ducting between straight parallel waves of each type. The impact of the natural crossings of nonlinear internal waves on horizontally ducted sound energy is studied theoretically and modeled numerically using a three-dimensional parabolic equation acoustic propagation code. A realistic sea surface elevation is synthesized from the directional spectrum of long swells and used for three-dimensional numerical modeling of acoustic propagation. As a result, considerable normal mode amplitude scintillations were observed and shown to be strongly dependent on horizontal azimuth, range and mode number. Full field numerical modeling of low frequency sound propagation through large sand waves located on a sloped bottom was performed using the high resolution bathymetry of the mouth of San Francisco Bay. Very strong acoustic ducting is shown to steer acoustic energy beams along the sand wave's curved crests.
by Alexey Alexandrovich Shmelev.
Ph.D.
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Little, Steven. "INTEGRABILITY OF A SINGULARLY PERTURBED MODEL DESCRIBING GRAVITY WATER WAVES ON A SURFACE OF FINITE DEPTH." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3285.
Full textAbstract:
Our work is closely connected with the problem of splitting of separatrices (breaking of homoclinic orbits) in a singularly perturbed model describing gravity water waves on a surface of finite depth. The singularly perturbed model is a family of singularly perturbed fourth-order nonlinear ordinary differential equations, parametrized by an external parameter (in addition to the small parameter of the perturbations). It is known that in general separatrices will not survive a singular perturbation. However, it was proven by Tovbis and Pelinovsky that there is a discrete set of exceptional values of the external parameter for which separatrices do survive the perturbation. Since our family of equations can be written in the Hamiltonian form, the question is whether or not survival of separatrices implies integrability of the corresponding equation. The complete integrability of the system is examined from two viewpoints: 1) the existence of a second first integral in involution (Liouville integrability), and 2) the existence of single-valued, meromorphic solutions (complex analytic integrability). In the latter case, a singular point analysis is done using the technique given by Ablowitz, Ramani, and Segur (the ARS algorithm) to determine whether the system is of Painlevé-type (P-type), lacking movable critical points. The system is shown by the algorithm to fail to be of P-type, a strong indication of nonintegrability.M.S.
Department of Mathematics
Sciences
Mathematical Science MS
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Hofmann, Hilmar. "Characteristics and implications of surface gravity waves in the littoral zone of a large lake (Lake Constance)." Göttingen : Cuvillier, 2008. http://d-nb.info/994900260/34.
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Hofmann, Hilmar. "Characteristics and implications of surface gravity waves in the littoral zone of a large lake (Lake Constance)." Göttingen Cuvillier, 2007. http://d-nb.info/99075491X/04.
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Trinh, Philippe H. "Exponential asymptotics and free-surface flows." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:e87b1f22-2569-4c0f-86a2-5bde76f34953.
Full textAbstract:
When traditional linearised theory is used to study free-surface flows past a surface-piercing object or over an obstruction in a stream, the geometry of the object is usually lost, having been assumed small in one or several of its dimensions. In order to preserve the nonlinear nature of the geometry, asymptotic expansions in the low-Froude or low-Bond limits can be derived, but here, the solution invariably predicts a waveless free-surface at every order. This is because the waves are in fact, exponentially small, and thus beyond-all-orders of regular asymptotics; their formation is a consequence of the divergence of the asymptotic series and the associated Stokes Phenomenon. In this thesis, we will apply exponential asymptotics to the study of two new problems involving nonlinear geometries. In the first, we examine the case of free-surface flow over a step including the effects of both gravity and surface tension. Here, we shall see that the availability of multiple singularities in the geometry, coupled with the interplay of gravitational and cohesive effects, leads to the discovery of a remarkable new set of solutions. In the second problem, we study the waves produced by bluff-bodied ships in low-Froude flows. We will derive the analytical form of the exponentially small waves for a wide range of hull geometries, including single-cornered and multi-cornered ships, and then provide comparisons with numerical computations. A particularly significant result is our confirmation of the thirty-year old conjecture by Vanden-Broeck & Tuck (1977) regarding the impossibility of waveless single-cornered ships.
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Buttle, Nicholas. "An efficient numerical scheme for free-surface flow over a three-dimensional bottom topography." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/117145/1/Nicholas_Buttle_Thesis.pdf.
Full textAbstract:
This thesis uses mathematical and computational modelling to explore water wave patterns that form on the surface of a stream when subject to some sort of wave-making disturbance. While a range of geometries are considered, the focus is on flow over a bottom topography that involves localised bumps. From a computational perspective, the key challenge is to solve the full governing equations using a sufficiently fine mesh to provide accurate solutions. To this end, we use a boundary integral approach together with a technique called a Jacobian-free Newton Krylov method. We present a range of numerical results and highlight the role of nonlinearity in three-dimensional water waves patterns.
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Hofmann, Hilmar [Verfasser]. "Characteristics and implications of surface gravity waves in the littoral zone of a large lake (Lake Constance) / vorgelegt von Hilmar Hofmann." Göttingen : Cuvillier, 2008. http://d-nb.info/994900260/34.
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Euvé, Léo-Paul. "Interactions ondes-courant-obstacle : application à la physique des trous noirs." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2280/document.
Full textAbstract:
Le projet de recherche consiste à observer en laboratoire la radiation de Hawking, cette prédiction stupéfiante de l'astrophysicien anglais Stephen Hawking faite en 1974 : les trous noirs ne sont pas noirs. Autrement dit, ils n'absorbent pas tout ce qui est à leur portée mais émettent un rayonnement. En plus des complications du fait que ces objets célestes sont à des milliers d'années-lumière, ce rayonnement est tellement faible que cela reviendrait à essayer d'entendre un murmure dans un concert de rock. Mais William Unruh, en 1981, a proposé une solution : utiliser des systèmes hydrodynamiques qui présentent les mêmes équations mathématiques qu'en astrophysique. Plus précisément, dans notre cas, nous utilisons la correspondance entre la propagation des ondes lumineuses au voisinage d'un trou noir et celles des ondes de surface dans un contre-courant rendu inhomogène par la présence d'un obstacle immergé. Pour cela, une compréhension approfondie de la mécanique des ondes de surface est nécessaire (bathymétrie variable, vorticité, non-linéarités…). Du côté technique, une méthode de mesure de surface libre a été développée et optimiséeThe aim of the PhD is the observation the Hawking radiation in the laboratory, this astounding prediction of the English astrophysicist Stephen Hawking made in 1974: black holes are not black. In other words, they do not absorb anything within reach but emit a radiation. In addition to the complications of the fact that these celestial objects are thousands of light years away, this radiation is so weak that it would be like trying to hear a whisper in a rock concert. But William Unruh, in 1981, proposed a solution: to use hydrodynamic systems which have the same mathematical equations as in astrophysics. More precisely, in our case, we use the correspondence between the propagation of light in the vicinity of a black hole and surface waves propagation on a inhomogeneous countercurrent (due to the presence of a submerged obstacle). For this, a thorough understanding of the surface waves physics is necessary (variable bathymetry, vorticity, non-linearities ...). On the technical side, a free surface measurement method has been developed and optimized
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Peureux, Charles. "Observation et modélisation des propriétés directionnelles des ondes de gravité courtes." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0091/document.
Full textAbstract:
Les vagues courtes sont omniprésentes à la surface des océans, avec des longueurs de quelques dizaines de mètres au mètre typiquement. Connaitre leurs directions de propagation en mer est important à plusieurs titres, notamment pour la compréhension de la dynamique de l'état de mer, des échanges air-mer ou de la dérive de particules en surface. Ces distributions directionnelles sont étudiées ici au regard des progrès récents réalisés en techniques d'instrumentation. L'analyse du bruit sismo-acoustique enregistré en grandes profondeurs permet d'extraire un comportement quasi-universel qui dépend indirectement de cette distribution à travers ladite intégrale de recouvrement. Il est cohérent avec des observations directes du champ de vagues obtenues à partir de reconstructions tridimensionnelles de la surface de l'océan. Alors que la direction de propagation des vagues longues s'aligne avec celle du vent, les vagues courtes s'en détachent d'autant plus à mesure que leurs échelles diminuent (bimodalité).La comparaison de ces observations avec les prédictions d'un modèle numérique de vagues, basé sur l'environnement WAVEWATCH®III, permet de constater que ces modèles sont qualitativement valables mais encore quantitativement incorrects. Une des possibilités explorées pour corriger cet effet est la prise en compte de sources de vagues courtes à ±90° de la direction du vent, qui pourraient être associées au déferlement des vagues longues. Une telle source à elle seule n'explique pas les formes des distributions directionnelles observées. D'autres mécanismes pourraient intervenir que de futures investigations pourront tenter de clarifierShort surface gravity waves are ubiquitous at the ocean surface, with lengths from a few tens of meters to a meter typically.Knowing their propagation directions at sea is important in several respects, especially for the understanding of sea-state dynamics, airsea interactions and particles surface drift.Their directional distributions are here investigated in the light of the recent progress made in instrumentation techniques. The analysis of ocean bottom seismo-acoustic noise records allows for the extraction of a quasi-universal behavior which indirectly depends on this distribution through the socalled overlap integral. It is coherent with direct observations of the wave field obtained from tri-dimensional reconstructions of the ocean surface elevation field. While the propagation direction of long waves aligns with the wind direction, short waves progressively detach from it towards small scales (bimodality).Comparing those measurements with the predictions of a spectral numerical wave model, based on WAVEWATCH®III environment, allows to realize that they provide qualitatively correct but quantitatively incorrect predictions. One of the possibilities here explored to correct for it, is by accounting for the sources of energy at ±90° to the wind direction, which could be associated with the breaking of long waves. This source term on its own does not explain the shapes of the observed directional distributions. Other mechanisms could come into play that future investigations will help clarify
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Gaillard, Pierre. "Calcul numérique des ondes de gravité dans les zones littorales et les aménagements portuaires : [thèse soutenue sur un ensemble de travaux]." Grenoble 1, 1988. http://www.theses.fr/1988GRE10079.
Full textAbstract:
Methodes de calcul sur ordinateur concernant la propagation de la houle, tenant compte des effets combines de refraction due aux fonds, de diffraction et reflexion dus aux ouvrages maritimes. Problemes de houles periodiques et irregulieres, et de houles regulieres (variation du niveau moyen de la mer et des courants), ainsi que de diffraction des ondes longues par des ouvrages offshore. Cas des seiches dans les ports et de houle irreguliere en canal en presence d'un ouvrage reflechissant. Comparaison avec essais en laboratoire et autres methodes theoriques
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Yuan, Ching-Feng, and 苑瀞丰. "On the Gravity Wave and Sea Surface Roughness Relationship in Coastal Ocean." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80099879949877083446.
Full textAbstract:
碩士國立中央大學
水文與海洋科學研究所
99
Physical surface roughness represents the actual elevation variations in various scales at the air-sea interface. It is affected by the gravity waves and the aerodynamic factors in the atmospheric boundary layer. It is one of the most crucial factors that determine the momentum, heat and water vapor exchange between the air and sea. Due to the shoaling of gravity waves in the coastal ocean, sea surface roughness features significant deviation compared with those observed in deep seas. The understanding of the characteristics of surface roughness in coastal ocean is of great importance since it has much influence on the climate change, water cycle, carbon cycle, wind driven current/storm surge predictions and the assessment and operation of offshore wind energy conversion. So far, parameters of Drag coefficient, Cd and Aerodynamic Roughness length Z0 are used to infer the sea surface roughness. However, they do not fully reflect the contribution of gravity waves to the surface roughness. In order to realize the characteristics of the sea surface roughness in the coastal ocean, the Mean Square Slope, MSS of surface elevation was adopted as the index to describe the sea surface roughness. In-situ observations were carried out at National Central University Coastal Observatory, TaiCOAST station located at the western coast of Taiwan. Synchronized observations of atmospheric boundary layer air-sea flux, gravity waves and current profiles, shore-based microwave radars were implemented during the period of northeast monsoon, i.e. from January 14, 2011 to January 31, 2011. The Drag coefficient is estimated using eddy-covariance method. The Roughness length is estimated by using the wind profile method and the spectral method. MSS is estimated from the surface elevation recorded by the three bottom-mounted Acoustic Doppler Current Profilers (ADCP). The surface tracking mode was implemented to obtain high resolution water elevation from the acoustic transducers. The wavenumber spectra were then calculated from the frequency spectra using the linear wave dispersion relationship. The slope spectrum can be derived and the MSS can be estimated by taking the integral of the slope spectrum. The magnitude of MSS is highly influenced by the spectral tail of full-range wavenumber spectrum. For non-saturated limited depth waves, it is not yet clear about the tail shape in high wavenumber range. In present study, six hypothetic spectral shapes were tested. Moreover, the criteria that distinguishes the spectral bands that governed by three wave interactions or quadruplet wave interactions, was determined. By using the criteria, the MSS that obtained from the lower-frequency slope spectra are associated with gravity waves; whereas those from high-frequency are associated with the turbulence. In present study, we use the absolute S-band radar backscatter intensity as reference to determine the tail property at the high wavenumber bands as well as the above-mentioned criteria. The result showed that the tail of full-range wavenumber spectrum is proportional to k-4. The best-fitted wavenumber cut-off wavenumber is about 42.3‧g/U102 . Futhermore, we discuss the dependency of the high-frequency MSS to the wind speed, and the low-frequency MSS to the wave age. The results show consistency with previous studies by Cox and Munk (1954). Moreover, when the wave age approximately equal to 0.8, the low-frequency MSS decreases. It is similar to the previous studies by Donelan(1990). Finally, an estimation of the contribution from the gravity waves to the surface roughness is about two-thirds at coastal oceans.
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Reaume, Jonathan Daniel. "Wave-Cavity Resonator: Experimental Investigation of an Alternative Energy Device." Thesis, 2015. http://hdl.handle.net/1828/6960.
Full textAbstract:
A wave cavity resonator (WCR) is investigated to determine the suitability of the
device as an energy harvester in rivers or tidal flows. The WCR consists of coupling
between self-excited oscillations of turbulent flow of water in an open channel along the
opening of a rectangular cavity and the standing gravity wave in the cavity. The device
was investigated experimentally for a range of inflow velocities, cavity opening lengths,
and characteristic depths of the water. Determining appropriate models and empirical
relations for the system over a range of depths allows for accuracy when designing
prototypes and tools for determining the suitability of a particular river or tidal flow as a
potential WCR site. The performance of the system when coupled with a wave
absorber/generator is also evaluated for a range piston strokes in reference to cavity wave
height. Video recording of the oscillating free-surface inside the resonator cavity in
conjunction with free-surface elevation measurements using a capacitive wave gauge
provides representation of the resonant wave modes of the cavity as well as the degree of
the flow-wave coupling in terms of the amplitude and the quality factor of the associated
spectral peak. Moreover, application of digital particle image velocimetry (PIV) provides
insight into the evolution of the vortical structures that form across the cavity opening.
Coherent oscillations were attainable for a wide range of water depths. Variation of the
water depth affected the degree of coupling between the shear layer oscillations and the
gravity wave as well as the three-dimensionality of the flow structure. In terms of the
power investigation, conducted with the addition of a load cell and linear table-driven
piston, the device is likely limited to running low power instrumentation unless it can be
up-scaled. Up-scaling of the system, while requiring additional design considerations, is
not unreasonable; large-scale systems of resonant water waves and the generation of large
scale vortical structures due to tidal or river flows are even observed naturally.Graduate
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reaumejd@uvic.ca