Bibliographies thématiques / Ocean-atmosphere interaction Mathematical models

Sommaire

Articles de revues
Thèses
Livres
Chapitres de livres
Actes de conférences

Littérature scientifique sur le sujet « Ocean-atmosphere interaction Mathematical models »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 29 janvier 2023

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres

Choisissez une source :

Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Ocean-atmosphere interaction Mathematical models ».

À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.

Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.

Articles de revues sur le sujet "Ocean-atmosphere interaction Mathematical models"

Qiao, Fangli, Yeli Yuan, Jia Deng, Dejun Dai, and Zhenya Song. "Wave–turbulence interaction-induced vertical mixing and its effects in ocean and climate models." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2065 (April 13, 2016): 20150201. http://dx.doi.org/10.1098/rsta.2015.0201.

Texte intégral

Résumé :

Heated from above, the oceans are stably stratified. Therefore, the performance of general ocean circulation models and climate studies through coupled atmosphere–ocean models depends critically on vertical mixing of energy and momentum in the water column. Many of the traditional general circulation models are based on total kinetic energy (TKE), in which the roles of waves are averaged out. Although theoretical calculations suggest that waves could greatly enhance coexisting turbulence, no field measurements on turbulence have ever validated this mechanism directly. To address this problem, a specially designed field experiment has been conducted. The experimental results indicate that the wave–turbulence interaction-induced enhancement of the background turbulence is indeed the predominant mechanism for turbulence generation and enhancement. Based on this understanding, we propose a new parametrization for vertical mixing as an additive part to the traditional TKE approach. This new result reconfirmed the past theoretical model that had been tested and validated in numerical model experiments and field observations. It firmly establishes the critical role of wave–turbulence interaction effects in both general ocean circulation models and atmosphere–ocean coupled models, which could greatly improve the understanding of the sea surface temperature and water column properties distributions, and hence model-based climate forecasting capability.

Styles APA, Harvard, Vancouver, ISO, etc.

Ostroukh, Andrey, Andrey Mavrin, and Nataliya Surkova. "Technological Processes Automation of Chemical Heat Treatment at Industrial Enterprises." Advanced Materials Research 1098 (April 2015): 120–25. http://dx.doi.org/10.4028/www.scientific.net/amr.1098.120.

Texte intégral

Résumé :

This paper presents analysis of chemical and thermal processing (CTP) methods to support multi-component gas atmosphere processes and their mathematical models as objects in the automated process control system (APCS). CTP mathematical models, algorithms, interaction structures and concepts of APCS components based on a specialized electronic controller have been proposed and implemented. The system provides a time control of all the necessary gas atmosphere parameters – its composition, temperature, pressure, with the possibility of using saturating medium of up to four components. Implementation of the system will improve the service properties of processed products, reduce the rate of spoilage and the psychophysical stress of the production staff, as well as reduce the overall CTP time.

Styles APA, Harvard, Vancouver, ISO, etc.

Mehra, Vinayak, Varun Gupta, and Pradeep Khanna. "MATHEMATICAL MODELLING TO PREDICT ANGULAR DISTORTION IN MIG WELDING OF STAINLESS STEEL 202 PLATES." Journal of Production Engineering 23, no. 2 (December 30, 2020): 16–20. http://dx.doi.org/10.24867/jpe-2020-02-016.

Texte intégral

Résumé :

In present research, mathematical models have been established to predict the angular distortion in Metal Inert Gas(MIG) welding for 6mm plates of SS 202 grade for butt welded joints. The filler metal used was a continuously fed solid metal wire of stainless steel (304L).100% Argon gas was used to serve the purpose of shielding the weld pool from the atmosphere as it does not dissociate at high temperatures. This prevented any turbulence in the welding arc and deterioration in weld quality. To obtain experimental samples, the design matrix was developed using the statistical technique of central composite rotatable design (CCRD). Analysis of Variance (ANOVA) technique was used for the adequacy check of the models developed. The models developed can be used to find direct and interaction effect of the input parameters, namely welding speed (WS), voltage (V), nozzle to plate distance (NPD), torch angle (Ɵ) and wire feed rate (WFR) on the angular distortion.

Styles APA, Harvard, Vancouver, ISO, etc.

Li, Ke Hua, Jin Yong Yu, and Jun Wei Lei. "Research on Modeling and Simulation of Sonar Performance Using Simulink." Applied Mechanics and Materials 138-139 (November 2011): 804–9. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.804.

Texte intégral

Résumé :

With respect to different weather and sea conditions, the acoustic model under ocean environment was proposed by analyzing the interaction characteristics between sonar and environment. Based on the sonar equation, the performance mathematical models of active and passive sonar were produced with considering acoustic characteristics of the target and parameters of the marine environment. Simulation results of target detection performance for different target types, sonar parameters and sea conditions show the validity of the proposed model.

Styles APA, Harvard, Vancouver, ISO, etc.

TURCANU, Alexandru, and Leonard-Călin-Valentin DOBRE. "DIMENSIONAREA SISTEMULUI DE PROPULSIE AL UNUI VEHICUL ELECTRIC. STUDIU DE CAZ." "ACTUALITĂŢI ŞI PERSPECTIVE ÎN DOMENIUL MAŞINILOR ELECTRICE (ELECTRIC MACHINES, MATERIALS AND DRIVES - PRESENT AND TRENDS)" 2020, no. 1 (February 10, 2021): 1–14. http://dx.doi.org/10.36801/apme.2020.1.4.

Texte intégral

Résumé :

This paper aims to present to readers concrete mathematical models, transposed into simulation schemes, to calculate the forces acting on a car at its interaction with the road and the atmosphere, to properly size the electric motor and batteries of an electric car. For the calculation of these forces, a table with predefined values such as vehicle mass, rolling resistance coefficient, gear ratio, wheel radius, was used throughout the work. In the second section of the paper, the values of the resistance forces that oppose the movement of the vehicle and the traction force necessary to overcome these resistive forces were determined. The mathematical calculation model was compiled in Matlab and the graphs in figures 3-9 were obtained.

Styles APA, Harvard, Vancouver, ISO, etc.

Heywood, Karen J., Sunke Schmidtko, Céline Heuzé, Jan Kaiser, Timothy D. Jickells, Bastien Y. Queste, David P. Stevens, et al. "Ocean processes at the Antarctic continental slope." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2019 (July 13, 2014): 20130047. http://dx.doi.org/10.1098/rsta.2013.0047.

Texte intégral

Résumé :

The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean–atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system.

Styles APA, Harvard, Vancouver, ISO, etc.

Mukhartova, Iuliia, Alexander Krupenko, Polina Mangura, and Alexander Olchev. "Mathematical Modeling of Vegetation Heterogeneity and Complex Topography Effects on Turbulent Exchange of GHG within the Atmospheric Surface Layer." Proceedings 2, no. 20 (October 17, 2018): 1310. http://dx.doi.org/10.3390/proceedings2201310.

Texte intégral

Résumé :

The local-scale 2D and 3D models of greenhouse gases (GHG) exchange between a non-uniform land surface and the atmosphere were developed. They are based on solution of the system of averaged Navier-Stokes, continuity and diffusion-advection equations. For numerical solution of the differential equations the stable finite-difference schemes were suggested. The models were applied to derive effects of complex topography and vegetation heterogeneity on 2D-3D air flow patterns, as well as on CO2 exchange within the atmospheric surface layer. Several numerical experiments were also provided to describe the air-flow re-establishing after its interaction with some obstacle (e.g., forest edge). Quantitative criteria for selection of the experimental sites for continuous eddy covariance flux measurements characterized by minimum effects of horizontal advection on measured fluxes were suggested.

Styles APA, Harvard, Vancouver, ISO, etc.

Kovalnogov, Vladislav N., Yuriy A. Khakhalev, Ekaterina V. Tsvetova, and Larisa V. Khakhaleva. "MATHEMATICAL MODELING AND NUMERICAL STUDY OF ATMOSPHERIC BOUNDARY LAYER NEAR WINDFARMS." Автоматизация процессов управления 3, no. 65 (2021): 33–40. http://dx.doi.org/10.35752/1991-2927-2021-3-65-33-40.

Texte intégral

Résumé :

The article analyzes Russian and foreign sources relating to the interaction of wind turbines with the surface layers of the atmosphere. It specifies the main problems of mathematical modeling of the atmospheric boundary layer near the wind farms due to adverse meteorological conditions, in particular, constant zero crossings in the autumn-winter period, various precipitation, a wide time range, air parameters, terrain and other features. The authors analyze the evolution of mathematical models of turbulence to describe the boundary layer near wind turbines from earlier to rapidly developing and currently used. To achieve greater accuracy and naturalism, it is proposed to use high-performance efficient algorithms based on combining scales and physics of phenomena. The authors propose a mathematical model for studying the state of the atmospheric polydisperse boundary layer under conditions of the Ulyanovsk wind farm, taking into account the dispersed particles in the flow, surface curvature, pressure gradient and other influences.

Styles APA, Harvard, Vancouver, ISO, etc.

Sangale, Bhagwan, U. M. Khodke H. W. Awari, and Vishal Ingle. "Crop Growth Simulation Modelling - A Review." International Journal of Current Microbiology and Applied Sciences 11, no. 1 (January 10, 2022): 78–84. http://dx.doi.org/10.20546/ijcmas.2022.1101.010.

Texte intégral

Résumé :

Agriculture plays a key role in overall economic and social wellbeing of the specially developing countries. Now it is the right option to increase the quality and quantity of food production through the technological and managerial interventions like crop growth and yield prediction models. Agricultural models are mathematical equations that represent the reactions that occur within the plant and the interactions between the plant and its environment. The model simulates or imitates the behaviour of real crop by predicting the growth of its components, such as leaves, roots, stems and grains. Thus, a crop growth model not only predicts the final state of total biomass or harvestable yield, but also contains quantitative information about major processes involved in the growth and development of a plant. Crop Growth Simulation models are a formal way to present quantitative knowledge about how a crop grows in interaction with its environment. Using weather data and other data about the crop environment, these models can simulate crop development, growth, yield, water, and nutrient uptake. Crop models are mathematical algorithms that capture the quantitative information of agronomy and physiology experiments in a way that can explain and predict crop growth and development. They can simulate many seasons, locations, treatments, and scenarios in a few minutes. Crop models contribute to agriculture in many ways. They help explore the dynamics between the atmosphere, the crop, and the soil, assist in crop agronomy, pest management, breeding, and natural resource management, and assess the impact of climate change.

Styles APA, Harvard, Vancouver, ISO, etc.

Gusev, E. M., and O. N. Nasonova. "Simulating of snow cover formation by the model of interaction between the land surface and the atmosphere (SWAP)." Ice and Snow 59, no. 2 (June 11, 2019): 167–81. http://dx.doi.org/10.15356/2076-6734-2019-2-401.

Texte intégral

Résumé :

In framework of the project «The Earth system Models – Snow Models Intercomparison Project» (ESMSnowMIP), calculations of snow storages were carried out on ten experimental sites organized for longterm monitoring of the snow cover variability in various regions of the globe. The calculation method is based on the physical and mathematical description of heat and moisture exchange processes occurring within the system «ground water – soil – vegetation cover/snow cover – surface layer of the atmosphere», and it is implemented in the form of the model of interaction between the land surface and the atmosphere (SWAP). The model was developed at the Institute of water problems (IWP) of Russian Academy of Sciences. The model makes possible to calculate components of water and heat balances and different characteristics of the hydrological regime of terrestrial ecosystems and river basins having different spatial scales and located in different natural conditions. Good quality of reproduction of the snow storages variability on all considered sites is reached that allows consideration of the SWAP model as one of the best models of the snow cover formation. Thus, the SWAP model has a sufficiently optimal degree of complexity of the algorithm for reproducing the dynamics of snow cover, which is necessary and sufficient in global and regional hydrological models describing formation of the water balance of the land in the cold regions of the planet, and can be used to create scenario forecasts of snow dynamics (as the important part of the cryosphere). This conclusion is verified by the results of using the SWAP model to reproduce long-term variability of snow storages in basins of the River Lena and the River Ob (with its tributary Irtysh) which are the two largest rivers of the Russian Federation. The calculated and measured characteristics of snow cover dynamics for these basins are shown to be in good agreement.

Styles APA, Harvard, Vancouver, ISO, etc.

Plus de sources

Thèses sur le sujet "Ocean-atmosphere interaction Mathematical models"

Kiss, Andrew Elek. "Dynamics of laboratory models of the wind-driven ocean circulation." View thesis entry in Australian Digital Theses Program, 2000. http://thesis.anu.edu.au/public/adt-ANU20011018.115707/index.html.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Santoso, Agus Mathematics &amp Statistics Faculty of Science UNSW. "Evolution of climate anomalies and variability of Southern Ocean water masses on interannual to centennial time scales." Awarded by:University of New South Wales. School of Mathematics and Statistics, 2005. http://handle.unsw.edu.au/1959.4/33355.

Texte intégral

Résumé :

In this study the natural variability of Southern Ocean water masses on interannual to centennial time scales is investigated using a long-term integration of the Commonwealth Scientic and Industrial Research Organisation (CSIRO) coupled climate model. We focus our attention on analysing the variability of Antarctic IntermediateWater (AAIW), Circumpolar DeepWater (CDW), and Antarctic Bottom Water (AABW). We present an analysis of the dominant modes of temperature and salinity (T - S) variability within these water masses. Climate signals are detected and analysed as they get transmitted into the interior from the water mass formation regions. Eastward propagating wavenumber-1, -2, and -3 signals are identied using a complex empirical orthogonal function (CEOF) analysis along the core of the AAIW layer. Variability in air-sea heat uxes and ice meltwater rates are shown by heat and salt budget analyses to control variability of Antarctic Surface Water where density surfaces associated with AAIW outcrop. The dominant mode in the CDW layer is found to exhibit an interbasin-scale of variability originating from the North Atlantic, and propagating southward into the Southern Ocean. Salinity dipole anomalies appear to propagate around the Atlantic meridional overturning circulation with the strengthening and weakening of North Atlantic Deep Water formation. In the AABW layer, T - S anomalies are shown to originate from the southwestern Weddell Sea, driven by salinity variations and convective overturning in the region. It is also demonstrated that the model exhibits spatial patterns of T - S variability for the most part consistent with limited observational record in the Southern Hemisphere. However, some observations of decadal T - S changes are found to be beyond that seen in the model in its unperturbed state. We further assess sea surface temperature (SST) variability modes in the Indian Ocean on interannual time scales in the CSIRO model and in reanalysis data. The emergence of a meridional SST dipole during years of southwest Western Australian rainfall extremes is shown to be connected to a large-scale mode of Indian Ocean climate variability. The evolution of the dipole is controlled by variations in atmospheric circulation driving anomalous latent heat uxes with wind-driven ocean transport moderating the impact of evaporation and setting the conditions favourable for the next generation phase of an opposite dipole.

Styles APA, Harvard, Vancouver, ISO, etc.

Alves, Jose Henrique Gomes de Mattos Mathematics UNSW. "A Saturation-Dependent Dissipation Source Function for Wind-Wave Modelling Applications." Awarded by:University of New South Wales. Mathematics, 2000. http://handle.unsw.edu.au/1959.4/17786.

Texte intégral

Résumé :

This study reports on a new formulation of the spectral dissipation source term Sds for wind-wave modelling applications. This new form of Sds features a nonlinear dependence on the local wave spectrum, expressed in terms of the azimuthally integrated saturation parameter B(k)=k^4 F(k). The basic form of this saturation-dependent Sds is based on a new framework for the onset of deep-water wave breaking due to the nonlinear modulation of wave groups. The new form of Sds is succesfully validated through numerical experiments that include exact nonlinear computations of fetch-limited wind-wave evolution and hindcasts of two-dimensional wave fields made with an operational wind-wave model. The newly-proposed form of Sds generates integral spectral parameters that agree more closely with observations when compared to other dissipation source terms used in state-of-the-art wind-wave models. It also provides more flexibility in controlling properties of the wave spectrum within the high wavenumber range. Tests using a variety of wind speeds, three commonly-used wind input source functions and two alternative full-development evolution limits further demonstrate the robustness and flexibility of the new saturation-dependent dissipation source term. Finally, improved wave hindcasts obtained with an implementation of the new form of Sds in a version of the WAM model demonstrate its potential usefulness in operational wind-wave forecasting applications.

Styles APA, Harvard, Vancouver, ISO, etc.

Arbic, Brian K. "Generation of mid-ocean eddies : the local baroclinic instability hypothesis." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/53047.

Texte intégral

Résumé :

Thesis (Ph.D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and the Woods Hole Oceanographic Institution), 2000. Includes bibliographical references (p. 284-290). by Brian Kenneth Arbic. Ph.D.

Styles APA, Harvard, Vancouver, ISO, etc.

Agudelo, Paula A. "Role of Local Thermodynamic Coupling in the Life Cycle of the Intraseasonal Oscillation in the Indo-Pacific Warm Pool." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19834.

Texte intégral

Résumé :

Intraseasonal oscillations (ISOs) are important elements of the tropical climate with time-scales of 20-80 day. The ISO is poorly simulated and predicted by numerical models. This work presents a joint diagnostic and modeling study of the ISO that examines the hypothesis that local coupling between the ocean and the atmosphere is essential to the existence and evolution of the ISO in the Indo-Pacific warm pool region. Low-level moistening during the transition phase preconditions the atmosphere for deep convection. The vertical structure of ISO from the ECMWF coupled model during different phases of the oscillation as well as the skill of the model in simulating the processes that occur during the transition phase were studied. The forecast skill of the vertical structure associated with the ISO is greater for winter than for summer events. Predictability of the convective period is poor when initialized before the transitional phase. When initialized within the transition period including lower tropospheric moistening, predictability increases substantially, although the model parameterizations appears to trigger convection quickly without allowing an adequate buildup of CAPE during the transition. The model tends to simulate a more stable atmosphere compared to data, limiting the production of deep convective events. Two different one-dimensional coupled models are used to analyze the role of local ocean-atmosphere coupling in generating ISO. The ocean component is a one-dimensional mixed layer model. In the first model the atmospheric component corresponds to the SCCM. Results suggest that convection in the model tends to be "overactive," inhibiting development of lower frequency oscillations in the atmosphere. In the second case, the atmospheric component is a semi-empirical model that allows reproducing the coupled ISO over long integration periods including only local mechanisms. In the semi-empirical scheme the rate of change of atmospheric variables is statistically related to changes in SST. The stable state of this model is a quasi-periodic oscillation with a time scale between 25 and 80 days that matches well the observed ISO. Results suggest that the period of the oscillation depends on the characteristics of the ocean mixed layer, with a higher frequency oscillation for a shallow mixed layer.

Styles APA, Harvard, Vancouver, ISO, etc.

Wei, Jiangfeng. "Land-atmosphere interaction and climate variability." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-05162007-151312/.

Texte intégral

Résumé :

Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008. Stieglitz, Marc, Committee Member ; Guillas, Serge, Committee Member ; Fu, Rong, Committee Member ; Curry, Judith, Committee Member ; Dickinson, Robert, Committee Chair.

Styles APA, Harvard, Vancouver, ISO, etc.

Dail, Holly Janine. "Atlantic Ocean circulation at the last glacial maximum : inferences from data and models." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78367.

Texte intégral

Résumé :

Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Cataloged from student-submitted PDF version of thesis. Includes bibliographical references (p. 221-236). This thesis focuses on ocean circulation and atmospheric forcing in the Atlantic Ocean at the Last Glacial Maximum (LGM, 18-21 thousand years before present). Relative to the pre-industrial climate, LGM atmospheric CO₂ concentrations were about 90 ppm lower, ice sheets were much more extensive, and many regions experienced significantly colder temperatures. In this thesis a novel approach to dynamical reconstruction is applied to make estimates of LGM Atlantic Ocean state that are consistent with these proxy records and with known ocean dynamics. Ocean dynamics are described with the MIT General Circulation Model in an Atlantic configuration extending from 35°S to 75°N at 1° resolution. Six LGM proxy types are used to constrain the model: four compilations of near sea surface temperatures from the MARGO project, as well as benthic isotope records of [delta]¹⁸O and [delta]¹³C compiled by Marchal and Curry; 629 individual proxy records are used. To improve the fit of the model to the data, a least-squares fit is computed using an algorithm based on the model adjoint (the Lagrange multiplier methodology). The adjoint is used to compute improvements to uncertain initial and boundary conditions (the control variables). As compared to previous model-data syntheses of LGM ocean state, this thesis uses a significantly more realistic model of oceanic physics, and is the first to incorporate such a large number and diversity of proxy records. A major finding is that it is possible to find an ocean state that is consistent with all six LGM proxy compilations and with known ocean dynamics, given reasonable uncertainty estimates. Only relatively modest shifts from modern atmospheric forcing are required to fit the LGM data. The estimates presented herein succesfully reproduce regional shifts in conditions at the LGM that have been inferred from proxy records, but which have not been captured in the best available LGM coupled model simulations. In addition, LGM benthic [delta]¹⁸O and [delta]¹³C records are shown to be consistent with a shallow but robust Atlantic meridional overturning cell, although other circulations cannot be excluded. by Holly Janine Dail. Ph.D.

Styles APA, Harvard, Vancouver, ISO, etc.

Verdy, Ariane. "Dynamics of marine zooplankton : social behavior, ecological interactions, and physically-induced variability." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43158.

Texte intégral

Résumé :

Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008. Includes bibliographical references (p. [221]-232). Marine ecosystems reflect the physical structure of their environment and the biological processes they carry out. This leads to spatial heterogeneity and temporal variability, some of which is imposed externally and some of which emerges from the ecological mechanisms themselves. The main focus of this thesis is on the formation of spatial patterns in the distribution of zooplankton arising from social interactions between individuals. In the Southern Ocean, krill often assemble in swarms and schools, the dynamics of which have important ecological consequences. Mathematical and numerical models are employed to study the interplay of biological and physical processes that contribute to the observed patchiness. The evolution of social behavior is simulated in a theoretical framework that includes zooplankton population dynamics, swimming behavior, and some aspects of the variability inherent to fluid environments. First, I formulate a model of resource utilization by a stage-structured predator population with density-dependent reproduction. Second, I incorporate the predator-prey dynamics into a spatially-explicit model, in which aggregations develop spontaneously as a result of linear instability of the uniform distribution. In this idealized ecosystem, benefits related to the local abundance of mates are offset by the cost of having to share resources with other group members. Third, I derive a weakly nonlinear approximation for the steady-state distributions of predator and prey biomass that captures the spatial patterns driven by social tendencies. Fourth, I simulate the schooling behavior of zooplankton in a variable environment; when turbulent flows generate patchiness in the resource field, schools can forage more efficiently than individuals. (cont.) Taken together, these chapters demonstrate that aggregation/ schooling can indeed be the favored behavior when (i) reproduction (or other survival measures) increases with density in part of the range and (ii) mixing of prey into patches is rapid enough to offset the depletion. In the final two chapters, I consider sources of temporal variability in marine ecosystems. External perturbations amplified by nonlinear ecological interactions induce transient ex-cursions away from equilibrium; in predator-prey dynamics the amplitude and duration of these transients are controlled by biological processes such as growth and mortality. In the Southern Ocean, large-scale winds associated with ENSO and the Southern Annular Mode cause convective mixing, which in turn drives air-sea fluxes of carbon dioxide and oxygen. Whether driven by stochastic fluctuations or by climatic phenomena, variability of the biogeochemical/physical environment has implications for ecosystem dynamics. by Ariane Verdy. Ph.D.

Styles APA, Harvard, Vancouver, ISO, etc.

Verdy, Ariane. "Variability of zooplankton and sea surface temperature in the Southern Ocean." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39197.

Texte intégral

Résumé :

Thesis (S.M.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006. Includes bibliographical references (p. 69-74). Interactions between physical and biological processes in the Southern Ocean have significant impacts on local ecosystems as well as on global climate. In this thesis, I present evidence that the Southern Ocean circulation affects the variability of zooplankton and sea surface temperature, both of which are involved in air-sea exchanges of carbon dioxide. First, I examine the formation of spatial patterns in the distribution of Antarctic krill (Euphausia superba) resulting from social behavior. Turbulence of the flow is found to provide favorable conditions for the evolution social behavior in an idealized biological-physical model. Second, I analyze observations of sea surface temperature variability in the region of the Antarctic circumpolar current. Results suggest that propagating anomalies can be explained as a linear response to local atmospheric forcing by the Southern Annular Mode and remote forcing by El-Nifio southern oscillation, in the presence of advection by a mean flow. by Ariane Verdy. S.M.

Styles APA, Harvard, Vancouver, ISO, etc.

Link, Shmuel G. "Field measurements of a swell band, shore normal, flux divergence reversal." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/67625.

Texte intégral

Résumé :

Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), June 2011. Cataloged from PDF version of thesis. Includes bibliographical references (p. 55-56). Throughout this thesis we will discuss the theoretical background and empirical observation of a swell band shore normal flux divergence reversal. Specifically, we will demonstrate the existence and persistence of the energy flux divergence reversal in the nearshore region of Atchafalaya Bay, Gulf of Mexico, across storms during the March through April 2010 deployment. We will show that the swell band offshore component of energy flux is rather insignificant during the periods of interest, and as such we will neglect it during the ensuing analysis. The data presented will verify that the greatest flux divergence reversal is seen with winds from the East to Southeast, which is consistent with theories which suggest shoreward energy flux as well as estuarine sediment transport and resuspension prior to passage of a cold front. Employing the results of theoretical calculations and numerical modeling we will confirm that a plausible explanation for this phenomena can be found in situations where temporally varying wind input may locally balance or overpower bottom induced dissipation, which may also contravene the hypothesis that dissipation need increase shoreward due to nonlinear wave-wave interactions and maturation of the spectrum. Lastly, we will verify that the data presented is consistent with other measures collected during the same deployment in the Atchafalaya Bay during March - April 2010. by Shmuel G. Link. S.M.

Styles APA, Harvard, Vancouver, ISO, etc.

Plus de sources

Livres sur le sujet "Ocean-atmosphere interaction Mathematical models"

Kagan, B. A. Ocean-atmosphere interaction and climate modelling. Cambridge [England]: Cambridge University Press, 1995.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

1945-, Norbury John, and Roulstone Ian, eds. Large-scale atmosphere-ocean dynamics. Cambridge, U.K: Cambridge University Press, 2002.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Marchuk, G. I. Matematicheskie modeli v geofizicheskoĭ gidrodinamike i chislennye metody ikh realizat͡s︡ii. Leningrad: Gidrometeoizdat, 1987.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Mitchell, Ross P. A numerical study of seasonal wind forcing effects on the California Current System. Monterey, Calif: Naval Postgraduate School, 1993.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Oberholzner, Werner. SWADE data guide. Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 1996.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Haines, Robert T. A numerical study of interannual wind forcing effects on the California Current System, 1980-1983. Monterey, Calif: Naval Postgraduate School, 1994.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Jankowski, Andrzej. Symulacja cyrkulacji wód Bałtyku dla wybranych miesięcy od kwietnia do listopada. Sopot: Polska Akademia Nauk, Instytut Oceanologii w Sopocie, 1998.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Bacon, Jeffrey L. A numerical study of the effects of wind forcing on the Chilean Current System. Monterey, Calif: Naval Postgraduate School, 1991.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Bayler, Eric Judson. Seasonal wind and ocean thermal forcing influences on the generation of the Leeuwin Current and its eddies. Monterey, Calif: Naval Postgraduate School, 1991.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Bacon, Jeffrey L. A numerical study of the effects of wind forcing on the Chilean Current System. Monterey, Calif: Naval Postgraduate School, 1991.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Plus de sources

Chapitres de livres sur le sujet "Ocean-atmosphere interaction Mathematical models"

Ocampo-Torres, Francisco J., Pedro Osuna, Héctor García-Nava, and Nicolas G. Rascle. "Ocean Surface Waves and Ocean-Atmosphere Interactions." In Mathematical and Computational Models of Flows and Waves in Geophysics, 35–66. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-12007-7_2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Battisti, David S. "Interannual Variability in Coupled Tropical Atmosphere-Ocean Models." In Climate-Ocean Interaction, 127–59. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2093-4_7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Gent, Peter R. "Parameterizing Eddies in Ocean Climate Models." In IUTAM Symposium on Advances in Mathematical Modelling of Atmosphere and Ocean Dynamics, 19–30. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0792-4_2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Tucciarone, Francesco L., Etienne Mémin, and Long Li. "Primitive Equations Under Location Uncertainty: Analytical Description and Model Development." In Mathematics of Planet Earth, 287–300. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18988-3_18.

Texte intégral

Résumé :

AbstractResolving numerically all the scale interactions of ocean dynamics in a high resolution realistic configuration is today far beyond reach, and only large scale representations can be afforded. In this work, we study a stochastic parameterization of the ocean primitive equations derived within the modelling under location uncertainty framework. First numerical assessments built with the NEMO core’s code are provided for a double-gyres configuration.

Styles APA, Harvard, Vancouver, ISO, etc.

Grimshaw, Roger, and Georg Gottwald. "Models for Instability in Geophysical Flows." In IUTAM Symposium on Advances in Mathematical Modelling of Atmosphere and Ocean Dynamics, 153–60. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0792-4_18.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Rõõm, Rein, and Aarne Männik. "Acoustic Filtration in Pressure-Coordinate Models." In IUTAM Symposium on Advances in Mathematical Modelling of Atmosphere and Ocean Dynamics, 221–26. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0792-4_29.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Jelloul, M. Ben, and X. J. Carton. "Asymptotic Models and Application to Vortex Dynamics." In IUTAM Symposium on Advances in Mathematical Modelling of Atmosphere and Ocean Dynamics, 105–10. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0792-4_10.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Gluhovsky, Alexander, and Christopher Tong. "Low-Order Models of Atmospheric Dynamics with Physically Sound Behavior." In IUTAM Symposium on Advances in Mathematical Modelling of Atmosphere and Ocean Dynamics, 147–52. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0792-4_17.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Kraus, Eric B., and Joost A. Businger. "The Planetary Boundary Layer." In Atmosphere-Ocean Interaction. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195066180.003.0010.

Texte intégral

Résumé :

The term planetary boundary layer (PBL) is often used as a synonym for the Ekman layer (i.e., for the region in which the convergence of the vertical flux of momentum is of the same order as the Coriolis force and the pressure gradient). The definition favored in this chapter is somewhat broader and includes the regions on both sides of the interface in which the vertical fluxes, not only of momentum but also of heat, moisture, and salinity, determine the vertical distribution of these properties. Such a definition may suggest as many different boundary layers as there are transported properties. This may be the case, but the various fluxes are coupled with each other to such an extent that it is usually possible to define a single layer in which interface effects remain significant. In Section 6.1 we shall deal first with the classic Ekman treatment of the steady-state motion field above and below the boundary of two incompressible, rotating laminar fluids. This will be followed by a discussion of transients and of integral horizontal transports. Section 6.2 deals with coherent structures—longitudinal rolls, thermal plumes, convection cells, and so on—that are common phenomena, particularly in the gravitationally unstable PBL. This is followed in Section 6.3 by a discussion of various parameterization schemes and models that have been used either to represent vertical fluxes or vertical profiles of conservative properties. Mixed-layer models, which are the topic of Section 6.4, are distinguished from these parameterization schemes by use of vertical integrals of the conservative properties. The resulting gain in simplicity is offset to some extent by a loss of detail. In Section 6.5 we shall discuss the merits and drawbacks of the different approaches in the two preceding sections. During his arctic expeditions on the ship Fram, late in the nineteenth century, Nansen noticed that the pack ice drifted at an angle of about 20-40° to the right of the surface wind. He interpreted this correctly as being due to the deflecting force of the earth’s rotation, and inferred further that the water below, which is dragged along by the ice, must be driven even further to the right.

Styles APA, Harvard, Vancouver, ISO, etc.

Han, Young-June, Michael E. Schlesinger, and W. Lawrence Gates. "Chapter 13 An Analysis of the Air-Sea-Ice Interaction Simulated by the Osu-Coupled Atmosphere-Ocean General Circulation Model." In Coupled Ocean-Atmosphere Models, 167–82. Elsevier, 1985. http://dx.doi.org/10.1016/s0422-9894(08)70709-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Actes de conférences sur le sujet "Ocean-atmosphere interaction Mathematical models"

Jensen, Gullik A., and Thor I. Fossen. "Mathematical Models for Model-Based Control in Offshore Pipelay Operations." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79372.

Texte intégral

Résumé :

This paper considers mathematical models for model-based controller design in offshore pipelay operations. Three classes of models for control design are discussed, real-world models suitable for controller design verification, controller and observer models which are used on-line in the control system implementation. The control application place requirements on the model with respect to the computational time, dynamic behavior, stability and accuracy. Models such as the beam model, two catenary models, as well as general finite element (FE) models obtained from computer programs were not able to meet all of the requirements, and two recent dynamic models designed for control are presented, which bridge the gap between the simple analytical and more complex FE models. For completeness, modeling of the pipelay vessel, stinger and roller interaction, soil and seabed interaction and environmental loads are discussed.

Styles APA, Harvard, Vancouver, ISO, etc.

Pesce, Celso Pupo, Roberto Ramos, Lauro Massao Yamada da Silveira, Rafael Loureiro Tanaka, Clo´vis de Arruda Martins, Fernanda Cristina Moraes Takafuji, Joa˜o Paulo Zi´lio Novaes, and Carlos Alberto Ferreira Godinho. "Structural Behavior of Umbilicals: Part I—Mathematical Modeling." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20892.

Texte intégral

Résumé :

Umbilicals for offshore application are very complex, since they combine elements of different mechanical behavior, such as steel tubes, thermoplastic hoses and power cores in a single structure, not to mention helically laid-up armouring layers and polymeric sheathes. This motivates continuous research on their mechanical modeling. This paper presents research undertaken in the structural behavior of umbilicals and focus on the mathematical modeling of the elements, which are gathered into concentric layers. Interaction between layers is included as well as helical lay-up of elements. The model here presented will be compared to a set of experimental results in a separate paper (Part II). An analytical model was developed combining equilibrium equations, geometric compatibility and constitutive relations to obtain a set of equations that describe the umbilical behavior under external loads. This set of equations is numerically solved to obtain contact pressures (or gaps) among layers, radial variations and strains in the elements (used to calculate the stresses). The model was built to be general in order to be able to cope with complex cross-sections designs often encountered. It was then implemented in a tailor made local analysis software, called UTILFLEX®. Both modeling and software resulted from a development program partnership between Prysmian Cables & Systems and University of Sa˜o Paulo. The paper will present modeling hypotheses and structural models that were used for steel tubes, hoses (thermoplastic and reinforced) and power cables and how the interaction among them has been treated.

Styles APA, Harvard, Vancouver, ISO, etc.

Peddle, Adam, Jie Dang, and Tom van Terwisga. "Towards a Model for Propeller-Ice Interaction." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83088.

Texte intégral

Résumé :

A reduced level of Arctic sea ice in recent years has resulted in an increase in commercial interest in shipping through previously inaccessible waters, such as the Northwest Passage. This interest has been significantly reinforced by the fact that vast amounts of natural resources are expected to exist in the Arctic regions. As such, the operation of vessels in ice-covered waters is currently a research topic of great relevance. Computational methods such as those based on potential flow have become invaluable in the evaluation and optimization of marine propellers, though as of this writing there exists a deficit of proven software tools to evaluate the operation of propellers in icy waters. In order to properly develop a model and a tool, a physical understanding of the involved processes is vital. A Cooperative Research Ships (CRS) project has been initiated with the ultimate aim of developing a software tool for the evaluation of propellers operating in ice which will operate within the CRS PROCAL environment. The research described in this paper is the first step in the development of such a tool. This paper is intended to serve primarily as a review of the existing literature on mathematical models of propeller-ice interaction as well as their numerical solutions. Such a study serves as a vital first step in the development of a complete method for propeller ice interaction. In addition to providing an overview of the current level of understanding in the field, this paper intends also to identify which areas are well understood and which require further investigation. It will highlight the strengths and shortcomings of current models with the intention of advancing towards the final model.

Styles APA, Harvard, Vancouver, ISO, etc.

Luo, Wei-lin, Zao-jian Zou, and Hong-liang Xiang. "Simulation of Ship Manoeuvring in the Proximity of a Pier by Using Support Vector Machines." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49644.

Texte intégral

Résumé :

Ship manoeuvrability has a close relationship with navigation safety. For a ship sailing in the proximity of a pier, its manoeuvrability is different from that in unrestricted waters. To predict the ship manoeuvrability in the proximity of a pier, the method of simulation based on mathematical model is used. The mathematical model of ship manoeuvring is obtained by using Support Vector Machines (SVM) based system identification, combined with free-running model tests. The interaction between the pier and the ship are considered in the mathematical model of ship manoeuvring motion. By analyzing the test results, SVM is applied to identify the hydrodynamic coefficients and the interaction coefficients in the mathematical model. By using the regressive models, the ship manoeuvring motions in the proximity of a pier are predicted. Comparisons between the predicted results and the test results demonstrate the validity of the proposed SVM method. Identification results, model test results as well, also confirm that navigation safety of the ship in the proximity of a pier can be guaranteed if the distance between the pier and the ship is under control.

Styles APA, Harvard, Vancouver, ISO, etc.

Nelli, Filippo, David M. Skene, Luke G. Bennetts, Micheal H. Meylan, Jason P. Monty, and Alessandro Toffoli. "Experimental and Numerical Models of Wave Reflection and Transmission by an Ice Floe." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61248.

Texte intégral

Résumé :

The marginal ice zone (MIZ) is the outer part of the sea-ice covered ocean, where ice can be found in the form of large floating chucks better known as floes. Since it is the area where the most part of the interaction between ice cover and ocean waves takes place, it requires careful modelling. However existing mathematical models, based on the traditional thin-plate theory, underestimate waves attenuation for the most energetic waves, since the energy dissipation occurring during the process is not taken into account. New laboratory experimental and direct numerical models are presented here. In the experimental model a thin plastic plate is tested under the action of incident waves with varying amplitudes and periods. The same experimental set-up was reproduced using a numerical model, which was developed by coupling a High Order Spectral Numerical Wave Tank with the Navier-Stokes solver IHFOAM. Data from the experiments and numerical models confirm that non-linear effects lead to a decrease of wave transmission.

Styles APA, Harvard, Vancouver, ISO, etc.

Rosetti, Guilherme Feitosa, Guilherme Vaz, and André Luís Condino Fujarra. "On the Effects of Turbulence Modeling on the Fluid-Structure Interaction of a Rigid Cylinder." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54989.

Texte intégral

Résumé :

The cylinder flow is a canonical problem for Computational Fluid Dynamics (CFD), as it can display several of the most relevant issues for a wide class of flows, such as boundary layer separation, vortex shedding, flow instabilities, laminar-turbulent transition and others. Several applications also display these features justifying the amount of energy invested in studying this problem in a wide range of Reynolds numbers. The Unsteady Reynolds Averaged Navier Stokes (URANS) equations combined with simplifying assumptions for turbulence have been shown inappropriate for the captive cylinder flow in an important range of Reynolds numbers. For that reason, recent improvements in turbulence modeling has been one of the most important lines of research within that issue, aiming at better prediction of flow and loads, mainly targeting the three-dimensional effects and laminar-turbulent transition, which are so important for blunt bodies. In contrast, a much smaller amount of work is observed concerning the investigation of turbulent effects when the cylinder moves with driven or free motions. Evidently, larger understanding of the contribution of turbulence in those situations can lead to more precise mathematical and numerical modeling of the flow around a moving cylinder. In this paper, we present CFD calculations in a range of moderate Reynolds numbers with different turbulence models and considering a cylinder in captive condition, in driven and in free motions. The results corroborate an intuitive notion that the inertial effects indeed play very important role in determining loads and motions. The flow also seems to adapt to the motions in such a way that vortices are more correlated and less influenced by turbulence effects. Due to good comparison of the numerical and experimental results for the moving-cylinder cases, it is observed that the choice of turbulence model for driven and free motions calculations is markedly less decisive than for the captive cylinder case.

Styles APA, Harvard, Vancouver, ISO, etc.

Wiktorski, Ekaterina, and Dan Sui. "Investigation of Stick-Slip Severity in a Coupled Axial-Torsional Drillstring Dynamics Using a Two DOF Finite Element Model." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19320.

Texte intégral

Résumé :

Abstract Drilling industry focuses nowadays on process optimization and cost reduction. Unwanted events should be predicted and avoided to increase drilling efficiency, improve safety, and save costs. Development and application of mathematical models enable us to understand the dynamics of the drilling process, learn parameter interaction and regulate system behavior. It is also a way to reduce the risk of occurrence of such events or mitigate negative outcomes. Challenges in two-dimensional modeling of drillstring vibrations include: (1) correct and precise interpretation of coupled two-dimensional motion, (2) use of sub-models, as down-hole weight on bit (WOB) model, downhole torque on bit (TOB) model and friction model, and (3) proper definition of associated boundary conditions. In this paper, we propose a two-dimensional axial-torsional model that considers these criteria. We present a new way to calculate downhole WOB, which can be used as an alternative to a constant WOB value. Dynamic boundary conditions are introduced to represent the respective phases of stick-slip. The model is formulated using the finite element method and intended for vertical wells. The main goal for developing this model is evaluation of the effect of surface rotational and axial velocities on the downhole drill bit dynamics. A dimensionless parameter, stick-slip severity, is used to represent the intensity of torsional oscillations. The developed model is based on mathematical relations and defined boundary conditions, which describe the dynamics of drillstring during stick-slip events. The model allows to study the effect of up to twelve input parameters on stick-slip severity to determine a suitable range. Results presented in this paper show that axial velocity applied from the surface may cause initiation of stick-slip, which in turn provokes axial vibrations. Increase in surface axial velocity leads to higher amplitude of downhole torsional oscillations. To mitigate stick-slip, surface rotational velocity should be increased.

Styles APA, Harvard, Vancouver, ISO, etc.

Chhabra, Narender K., James R. Scholten, and Jeffrey B. Lozow. "Wave-Generated Forces and Moments on Submersibles: Models for Dynamic Simulation at Periscope Depth." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1257.

Texte intégral

Résumé :

Abstract Analysis of the wave-induced motion of underwater vehicles near the ocean surface is a difficult task. First, the action of the fluid must be decomposed into ideal (inviscid) and real (viscous) effects. Next, each effect must be modeled as to its interaction with the submerged body. The effect of the body on the waves must be considered. In shallow water, the ocean bottom has many effects: energy-dissipation tends to reduce wave height; land-proximity restricts the wave direction; and the bottom boundary changes the shape of the waves, attenuating the vertical (but not the horizontal) component of motion. This paper presents mathematical models for predicting realistic wave-generated forces and moments on submersible vehicles. Included are models which generate typical wave spectra for deep and shallow waters, models for wave kinematics as affected by flat or sloping bottoms, and models for forces and moments on submersibles due to these surface waves. Forces and moments are computed using two alternative methods. One is a fast method based on analytical integration of dynamic pressure forces over the surface of an elongated ellipsoidal body. It gives first-order forces and moments limited to horizontal and restrained bodies. The second method, based on the Froude-Krylov approach, uses numerical integration of dynamic pressures to give forces and moments on any shape hull in any attitude. Unlike the first method, it can be extended to include broaching of the sea surface by the body. Hydrodynamic forces due to an unrestrained body’s motion are accounted for with “added mass” terms. These mathematical models have been implemented in the C language in a real-time computer simulation. They are actively used to study the dynamic performance and control of submersibles at periscope depths.

Styles APA, Harvard, Vancouver, ISO, etc.

Randolph, Mark, and Peter Quiggin. "Non-Linear Hysteretic Seabed Model for Catenary Pipeline Contact." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79259.

Texte intégral

Résumé :

This paper presents a new mathematical model of the reaction force normal to the seabed, experienced by a pipeline or catenary riser in contact with the seabed. Such contact is currently often modeled using simple seabed contact models, and it is hoped that improved modeling of the seabed interaction will give more accurate predictions of system behavior, in particular for fatigue analysis. The model uses as its primary data the pipe diameter, the seabed soil shear strength profile with depth and the soil density. Additional parameters, in particular the maximum normalized stiffness of the pipe-soil response following reversal of motion, are used to derive non-linear hyperbolic functions that model the seabed resistance force as a function of the penetration. Different functions are used for the initial penetration, for uplift and for repenetration, and the function parameters are updated each time a penetration reversal occurs. This enables the model to capture the hysteretic behavior of the seabed response and the increasing penetration of the pipe under cycles of load in the vertical plane, although no attempt is made to model softening of the soil due to remolding. The paper documents the model equations and discusses their background and characteristics. The various non-dimensional parameters of the model that are used to control the resistance response are described and their effects are illustrated. The model is intended for use in practical engineering analysis and has been implemented in a commercial riser analysis program (Orcina 2008). The paper compares results obtained using the model against measured results for pipe-seabed interaction from laboratory and harbor experiments. It also presents results of using the model for engineering analysis of a riser under cyclic motions, and compares the resulting fatigue life with that obtained using a simple linear seabed model.

Styles APA, Harvard, Vancouver, ISO, etc.

Zhan, Dexin, and David Molyneux. "3-Dimensional Numerical Simulation of Ship Motion in Pack Ice." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83105.

Texte intégral

Résumé :

In OMAE2010, the authors presented a two dimensional numerical simulation for predicting ship maneuvering in pack ice. This paper is an expansion of this analysis to include a three dimensional numerical simulation for an arctic drill ship moving in pack ice (with ice concentration up to 90%) using a discrete element modeling program (DECICE3D) combined with a ship maneuvering code (SML). The mathematical models of ship motion, ice motion and ship-ice interaction are introduced in the paper. Ship motions of steady drift angle, turning about a turret, turning circle and zigzag maneuvers in pack ice are simulated. The results of the simulations are compared with experimental data or results of simulations for ice free conditions. A sensitive study for the effects of the mass damping term used in the equations of motion is conducted.

Styles APA, Harvard, Vancouver, ISO, etc.

Nous offrons des réductions sur tous les plans premium pour les auteurs dont les œuvres sont incluses dans des sélections littéraires thématiques. Contactez-nous pour obtenir un code promo unique!