Consulta: subjectFacets:"Numerical modelling"
Registros recuperados: 21
Data/hora: 07/06/2024 05:16:53

Suspended Sediment Dynamics in the Macrotidal Seine Estuary (France) - Part 2: Numerical Modeling of Sediment Fluxes and Budgets Under Typical Hydrological and Meteorological Conditions
Provedor de dados: 5
Autores: Schulz, Elisabeth; Grasso, Florent; Le Hir, Pierre; Verney, Romaric; Thouvenin, Benedicte.
Understanding the sediment dynamics in an estuary is important for its morphodynamic and ecological assessment as well as, in case of an anthropogenically controlled system, for its maintenance. However, the quantification of sediment fluxes and budgets is extremely difficult from in-situ data and requires thoroughly validated numerical models. In the study presented here, sediment fluxes and budgets in the lower Seine Estuary were quantified and investigated from seasonal to annual time scales with respect to realistic hydro- and meteorological conditions. A realistic three-dimensional process-based hydro- and sediment-dynamic model was used to quantify mud and sand fluxes through characteristic estuarine cross-sections. In addition to a reference...
Tipo: Text
Palavras-chave: Macrotidal estuary; Sediment fluxes; Numerical modelling; Mud/sand; Wind/waves; River discharge.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00416/52772/53640.pdf

Simulation of tides, residual flow and energy budget in the Gulf of California
Provedor de dados: 5
Autores: Carbajal, N; Backhaus, Jo.
With the application of a two-dimensional nonlinear hydrodynamical-numerical semi-implicit model, the principal tides M(2), S(2), K(2), N(2), K(1), P(1) and O(1) were studied. Energy budgets of the semi-diurnal M(2) and S(2) were calculated separately. The linear sum of these budgets was compared with the tidal energy budget obtained when these two tidal constituents interact. Since a quadratic form for the bottom friction was used, remarkable differences were found. The results show that in the area of the Colorado River delta, the dissipation of tidal energy is very strong. Intense tidal currents were observed in the same region and over the Salsipuedes Sill. Energy budgets calculated for forcing waves of different periods, but of the same amplitude,...
Tipo: Text
Palavras-chave: Modèle numérique; Marée; Courant résiduel; Bilan énergétique; Seiche; Numerical modelling; Tide; Residual flow; Energy budget; Seiche.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00325/43666/43204.pdf

Variation of the tidal properties around Gran Canaria
Provedor de dados: 5
Autores: Martinez, A; Perez, E; Bruno, M.
Analysis of water level and current meter series from different locations on the island shelf of Gran Canaria reveals strong variations in tidal properties. Semidiurnal sea level amplitudes agree with the results obtained from global tidal models for this region only on the northern coast of the island, while they decrease towards the southwest (10 cm difference for the M-2 constituent). Semidiurnal currents present maxima at the southeastern and northwestern extremities of the island (30-40 cm s(-1) for M-2) and minima in the north-northeast and southwest (3-6 cm s(-1) for M-2), showing simultaneous strong changes in the phase. Diurnal levels and currents display smaller variations than the semidiurnal band. The behaviour of semidiurnal constituents is...
Tipo: Text
Palavras-chave: Marée; Courant de marée; Île; Modélisation numérique; Îles Canaries; Tide; Tidal current; Island; Numerical modelling; Canary Islands.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00325/43625/43258.pdf

Modélisation haute-résolution des courants dans le Golfe de Guinée : Etude des oscillations bimensuelles.
Provedor de dados: 5
Autores: Guiavarch, Catherine.
Currentmeter measurements on the continental slope of the Gulf of Guinea (near 7°40 S) point out a biweekly oscillation of the currents, bottom intensified and oriented along the bathymetry. Those energetic oscillations dominate the signal. A three-dimensional high-resolution primitive equation model  (NEMO/OPA) of the Gulf of Guinea has been developed to study the oscillations and their forcing mechanism.  The data does not support the tide as a forcing mechanism and the wind-forced regional model reproduces biweekly oscillations, which fit the data quite well. Experiments with different forcings have been run to explore the origin of the biweekly variability. Those experiments highlight the equatorial origin of the oscillations forced by equatorial...
Tipo: Text
Palavras-chave: Deep current; Biweekly oscillations; Equatorial waves; Coastal trapped waves; Gulf of Guinea; Numerical modelling; Courant profond; Oscillations bimensuelles; Ondes équatoriales; Ondes piégées à la côte; Golfe de Guinée; Modélisation numérique.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/these-3647.pdf

Dynamique sédimentaire multiclasse : de l’étude des processus à la modélisation en Manche
Provedor de dados: 5
Autores: Blanpain, Olivier.
The purpose of this work is the implementation of a sediment transport model in the English Channel. The design of such a model requires the identification of the physical processes, their modelling and their in-situ validation. Because of the sedimentary particularities of the study area, modelling of the mechanical behaviour of a non uniform mixture of sediments and particularly of the fine grains within a coarse matrix is required. This study focused on the characterization of the relevant processes by acquisition of experimental and in-situ data. Data acquired in hydro-sedimentary conditions comparable to those found in the English Channel are scarce. A new instrument and image processing technique were specifically conceived and implemented in-situ to...
Tipo: Text
Palavras-chave: Manche; Sédiment multiclasse; Modélisation numérique; Morphodynamique; Charriage; Tri sédimentaire; Mesures in-situ; Traitement d’images; Mesures en canal; English Channel; Graded sediment; Numerical modelling; Morphodynamics; Bedload; Sediment sorting; In-situ data; Image processing; Flume experiments.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00003/11426/7962.pdf

Towards an understanding of Labrador Sea salinity drift in eddy-permitting simulations
Provedor de dados: 5
Autores: Rattan, Sanjay; Myers, Paul G.; Treguier, Anne-marie; Theetten, Sebastien; Biastoch, Arne; Boening, Claus.
Model drift in the Labrador Sea in eddy permitting model simulations is examined using a series of configurations based on the NEMO numerical framework. There are two phases of the drift that we can identify, beginning with an initial rapid 3-year period, associated with the adjustment of the model from its initial conditions followed by an extended model drift/adjustment that continued for at least another decade. The drift controlled the model salinity in the Labrador Sea, over-riding the variability. Thus, during this initial period, similar behavior was observed between the inter-annually forced experiments as with perpetual year forcing. The results also did not depend on whether the configuration was global, or regional North Atlantic Ocean. The...
Tipo: Text
Palavras-chave: Numerical modelling; Labrador Sea; Model salinity drift; Boundary currents; Eddy-permitting models.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00013/12411/9226.pdf

Bottom trawling contribution to the spatio-temporal variability of sediment fluxes on the continental shelf of the Bay of Biscay (France)
Provedor de dados: 5
Autores: Mengual, Baptiste; Le Hir, Pierre; Cayocca, Florence; Garlan, T.
Based on experiments, a trawling-induced erosion dynamics was included in a 3D realistic and pre-validated hydro-sedimentary model so as to assess its contribution to the overall regional sediment dynamics in the specific case of the Bay of Biscay continental shelf. The effect of trawling was investigated throughout a 5-year period in terms of horizontal/vertical fluxes and changes in seabed mud content, and compared to the natural variability of sediment fluxes at different spatio-temporal scales. Trawling is shown in the model to significantly contribute to sediment re-suspension, and changes in the seabed at the scale of the shelf. The contribution of trawling to re-suspension is &gt;80% during the high fishing season at many locations on the outer...
Tipo: Text
Palavras-chave: Sediment fluxes; Bottom trawling; Numerical modelling; Bay of Biscay; Continental shelf.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00500/61146/64574.pdf

Oceanic response to atmospheric forcing derived from different climatic data sets. Intercomparison study for the Black Sea
Provedor de dados: 5
Autores: Staneva, Jv; Stanev, Ev.
Available climatic and atmospheric analysis data have been used to prepare forcing functions for the Black Sea numerical model, based on the Bryan-Semtner-Cox Modular Ocean Model and including parameterizations for the atmosphere-ocean exchange, inflow through the strait of Bosphorus and the Mediterranean plume. Atmospheric data from different sources are compared and the drawbacks of some of them illustrated. A new wind stress data set, based on ship observations, is prepared. Compared to the existing wind stress estimates, the present ones use additional data and more accurate parameterization of the boundary layer physics. The intercomparison between forcing data sets is focused on the heat flux and freshwater flux at the sea surface. The model...
Tipo: Text
Palavras-chave: Mer Noire; Échange d'eau; Échange de chaleur; Tension du vent; Modélisation numérique; Black Sea; Water exchange; Heat exchange; Wind stress; Numerical modelling.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00325/43664/43206.pdf

Observation et modélisation des propriétés directionnelles des ondes de gravité courtes
Provedor de dados: 5
Autores: Peureux, Charles.
Short 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...
Tipo: Text
Palavras-chave: Vagues courtes; Bruit sismoacoustique; Modélisation numérique; Intégrale de recouvrement; Bimodalité; Short ocean surface waves; Seismoacoustic noise; Stereo-video; Numerical modelling; Overlap integral; Bimodality.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00498/60970/64378.pdf

Modelling Fine Sediment Dynamics: Towards a Common Erosion Law for Fine Sand, Mud and Mixtures
Provedor de dados: 5
Autores: Mengual, Baptiste; Le Hir, Pierre; Cayocca, Florence; Garlan, Thierry.
This study describes the building of a common erosion law for fine sand and mud, mixed or not, in the case of a typical continental shelf environment, the Bay of Biscay shelf, characterized by slightly energetic conditions and a seabed mainly composed of fine sand and muddy sediments. A 3D realistic hydro-sedimentary model was used to assess the influence of the erosion law setting on sediment dynamics (turbidity, seabed evolution). A pure sand erosion law was applied when the mud fraction in the surficial sediment was lower than a first critical value, and a pure mud erosion law above a second critical value. Both sand and mud erosion laws are formulated similarly, with different parameters (erodibility parameter, critical shear stress and power of the...
Tipo: Text
Palavras-chave: Sand-mud mixture erosion; Numerical modelling; Non-cohesive to cohesive transition.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00394/50588/51280.pdf

Initiation of gas-hydrate pockmark in deep-water Nigeria: Geo-mechanical analysis and modelling
Provedor de dados: 5
Autores: Riboulot, Vincent; Sultan, Nabil; Imbert, P.; Ker, Stephan.
A review of recent literature shows that two geomorphologically different types of pockmarks, contribute to gas seepage at the seafloor. Type-1 pockmarks are defined as seafloor craters associated to fluid seepage and are the most classical type referred to as “pockmarks” in the literature. In contrast, Type-2 pockmarks reveal a complex seafloor morphology that may result from the formation/decomposition of gas hydrates in underlying sedimentary layers.  Interpretation of very-high-resolution seismic data, sedimentological analyses and geotechnical measurements acquired from the Eastern Niger Submarine Delta reveal that Type-2 pockmarks are associated to the presence at depth of a conical body of massive gas hydrates. Based on acquired data, theoretical...
Tipo: Text
Palavras-chave: Pockmarks; Gas hydrates; VHR seismic data; Piezocone; Numerical modelling; Niger Delta.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00301/41215/40643.pdf

3D modelling in the Sado estuary using a new generic vertical discretization approach
Provedor de dados: 5
Autores: Martins, F; Leitao, P; Silva, A; Neves, R.
Sado estuary (Portugal) is a mesotidal well-mixed estuary. The flow however, displays strong three-dimensional features associated with bathymetry variations. The flow is simulated using a three-dimensional primitive equation model based on the finite-volume method and incorporating a new concept for the vertical discretization. The innovative features of the model are analysed and the advantages of the finite-volume method to implement the generic vertical discretization are put into evidence. The model was validated using water level, velocity and salinity measurements in several stations along the estuary. Results show the influence of main channel's strong curvature on the generation of secondary flows inside the estuary. The steep bathymetry of the...
Tipo: Text
Palavras-chave: Estuaires; Modélisation numérique; Écoulements secondaires; Recirculation verticale; Discrétisation verticale générique; Estuaries; Numerical modelling; Secondary flows; Vertical recirculation; Generic vertical discretization.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00291/40270/38641.pdf

Numerical modelling of heterogeneous sediment transport: new insights for particulate radionuclide transport and deposition
Provedor de dados: 5
Autores: Rivier, Aurélie; Le Hir, Pierre; Bailly Du Bois, Pascal; Laguionie, Philippe; Morillon, Mehdi.
A sediment transport module which solves simultaneously bedload and suspended load is developed, in a context of multiclass sediment transport. Different approaches are used to simulate each transport mode: (i) bedload transport results from divergence of transport capacity and (ii) suspension transport is solved using erosion and settling fluxes associated with advection/diffusion equation. A focus is made on the significance of hiding and exposure processes in case of heterogeneous sediment bed. Their influence is strong on bedload sediment transport, and induces specific trends of sediment sorting in sand dunes. The application to heterogeneous sediment dynamics in the macrotidal area of the Normand Breton Gulf (English Channel), show that hiding and...
Tipo: Text
Palavras-chave: Sediment transport; Numerical modelling; Hiding; Exposure; Bedload; Suspension.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00394/50580/51274.pdf

Numerical modelling of mixed-sediment consolidation
Provedor de dados: 5
Autores: Grasso, Florent; Le Hir, Pierre; Bassoullet, Philippe.
Sediment transport modelling in estuarine environments, characterised by cohesive and non-cohesive sediment mixtures, has to consider a time variation of erodibility due to consolidation. Generally, validated by settling column experiments, mud consolidation is now fairly well simulated; however, numerical models still have difficulty to simulate accurately the sedimentation and consolidation of mixed sediments for a wide range of initial conditions. This is partly due to the difficulty to formulate the contribution of sand in the hindered settling regime when segregation does not clearly occur. Based on extensive settling experiments with mud-sand mixtures, the objective of this study was to improve the numerical modelling of mixed-sediment consolidation...
Tipo: Text
Palavras-chave: Mud-sand mixtures; Hindered settling; Consolidation; Experiments; Numerical modelling; Segregation.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00254/36539/35168.pdf

Impact of Tropical Cyclones on Inhabited Areas of the SWIO Basin at Present and Future Horizons. Part 1: Overview and Observing Component of the Research Project RENOVRISK-CYCLONE
Provedor de dados: 5
Autores: Bousquet, Olivier; Barruol, Guilhem; Cordier, Emmanuel; Barthe, Christelle; Bielli, Soline; Calmer, Radiance; Rindraharisaona, Elisa; Roberts, Gregory; Tulet, Pierre; Amelie, Vincent; Fleischer-dogley, Frauke; Mavume, Alberto; Zucule, Jonas; Zakariasy, Lova; Razafindradina, Bruno; Bonnardot, François; Singh, Manvendra; Lees, Edouard; Durand, Jonathan; Mekies, Dominique; Claeys, Marine; Pianezze, Joris; Thompson, Callum; Tsai, Chia-lun; Husson, Romain; Mouche, Alexis; Ciccione, Stephane; Cattiaux, Julien; Chauvin, Fabrice; Marquestaut, Nicolas.
The international research program “ReNovRisk-CYCLONE” (RNR-CYC, 2017–2021) directly involves 20 partners from 5 countries of the south-west Indian-Ocean. It aims at improving the observation and modelling of tropical cyclones in the south-west Indian Ocean, as well as to foster regional cooperation and improve public policies adapted to present and future tropical cyclones risk in this cyclonic basin. This paper describes the structure and main objectives of this ambitious research project, with emphasis on its observing components, which allowed integrating numbers of innovative atmospheric and oceanic observations (sea-turtle borne and seismic data, unmanned airborne system, ocean gliders), as well as combining standard and original methods...
Tipo: Text
Palavras-chave: Tropical cyclone; South-west Indian Ocean; Gliders; Unmanned airborne system; Biologging; Sea turtles; Global satellite navigation system; ReNovRisk; Numerical modelling; Climate modelling; Austral and cyclonic swells; Seismic data.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00691/80281/83366.pdf

Global scale analysis and modeling of primary microseisms
Provedor de dados: 5
Autores: Gualtieri, L; Stutzmann, E; Juretzek, C; Hadziioannou, C; Ardhuin, Fabrice.
Primary microseism is the less studied seismic background vibration of the Earth. Evidence points to sources caused by ocean gravity waves coupling with the seafloor topography. As a result, these sources should be in water depth smaller than the wavelength of ocean waves. Using a state-of-the-art ocean wave model, we carry out the first global-scale seismic modeling of the vertical-component power spectral density of primary microseisms. Our modeling allows us to infer that the observed weak seasonality of primary microseisms in the southern hemisphere corresponds to a weak local seasonality of the sources. Moreover, a systematic analysis of the source regions that mostly contribute to each station reveals that stations on both the East and West sides of...
Tipo: Text
Palavras-chave: Numerical modelling; Computational seismology; Seismic noise; Theoretical Seismology.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00487/59842/62990.pdf

Influence of morphological changes on suspended sediment dynamics in a macrotidal estuary: diachronic analysis in the Seine Estuary (France) from 1960 to 2010
Provedor de dados: 5
Autores: Grasso, Florent; Le Hir, Pierre.
Estuaries are subject to extensive morphological changes through human activities, such as deepening and narrowing via dredging and channelization. The estuary sediment load, characterised by the estuarine turbidity maximum (ETM), can severely increase in response to channel deepening, shifting the estuary from a natural to hyperturbid state. The main processes driving the estuarine circulation, hydrology and sediment dynamics are relatively well known. However, their relative influence on suspended sediment concentration (SSC), as well as their role in the transition toward hyperturbid estuaries, is still a subject of debate. Therefore, this study aims at investigating the relative contribution of key estuarine drivers (gravitational circulation and tidal...
Tipo: Text
Palavras-chave: Estuary deepening and narrowing; Sediment dynamics; Turbidity maximum; Tidal asymmetry; Stratification; Numerical modelling; Morphological changes.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00479/59046/65965.pdf

Climate Change Influences Carrying Capacity in a Coastal Embayment Dedicated to Shellfish Aquaculture
Provedor de dados: 5
Autores: Guyondet, T.; Comeau, L. A.; Bacher, Cedric; Grant, J.; Rosland, R.; Sonier, R.; Filgueira, R.
A spatially explicit coupled hydrodynamic-biogeochemical model was developed to study a coastal ecosystem under the combined effects of mussel aquaculture, nutrient loading and climate change. The model was applied to St Peter's Bay (SPB), Prince Edward Island, Eastern Canada. Approximately 40 % of the SPB area is dedicated to mussel (Mytilus edulis) longline culture. Results indicate that the two main food sources for mussels, phytoplankton and organic detritus, are most depleted in the central part of the embayment. Results also suggest that the system is near its ultimate capacity, a state where the energy cycle is restricted to nitrogen-phytoplankton-detritus-mussels with few resources left to be transferred to higher trophic levels. Annually, mussel...
Tipo: Text
Palavras-chave: Climate change; Nutrient loading; Mussel culture; Carrying capacity; Coastal ecosystem; Numerical modelling.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00275/38624/37191.pdf

Numerical procedure for estimating temperature in solarized soils
Provedor de dados: 86
Autores: Tiba,Chigueru; Ghini,Raquel.
The objective of this work was to develop a simplified numerical procedure for the estimation of accumulated monthly hours of solarized soil temperatures. The proposed model requires monthly means of daily solar radiation and maximum air temperature as input data, and a daily pattern of temperature variation assumed to be sine-shaped. The procedure was verified using observations made during the years 1992 and 1993 in Jaguariúna, SP. The proposed procedure can predict monthly temperature hours at 10 cm depth in the solarized soil, with acceptable accuracy, in the region for which it was developed.
Tipo: Info:eu-repo/semantics/report
Palavras-chave: Soil disinfestation; Physical control; Soil pathogens; Alternative methods; Solar energy; Numerical modelling.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2006000300023

Patterns of sediment dispersion coastwise the State of Bahia - Brazil
Provedor de dados: 42
Autores: BITTENCOURT,ABÍLIO CARLOS DA SILVA PINTO; DOMINGUEZ,JOSÉ MARIA LANDIM; MARTIN,LOUIS; SILVA,IRACEMA REIMÃO.
Using the average directions of the main wave-fronts which approach the coast of Bahia State - coinciding with that of the main wind occurring in the area - and of their periods, we define a wave climate model based on the construction of refraction diagrams. The resulting model of sediment transport was able to reproduce, in a general way, the sediment dispersion patterns furnished by geomorphic indicators of the littoral drift. These dispersion patterns control the generation of different types of sediment accumulations and of coastal stretches under erosion. We demonstrate that the presence of the Abrolhos and Corumbaú Point coral reefs is an important factor controlling the sediment dispersion patterns, since them act as a large protection against the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Littoral drift; Wave refraction; Numerical modelling; State of Bahia; Brazil.
Ano: 2000
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000200012

A significant longshore transport divergence zone at the Northeastern Brazilian coast: implications on coastal Quaternary evolution
Provedor de dados: 42
Autores: BITTENCOURT,ABÍLIO C.S.P.; MARTIN,LOUIS; DOMINGUEZ,JOSÉ M.L.; SILVA,IRACEMA R.; SOUSA,DAIANA L.
By using the mean directions of the wave-fronts approaching the Brazilian northeastern coastal stretch comprised between the localities of Real river (Sergipe State) and Galinhos (Rio Grande do Norte State) - coincident with those of the main winds occurring in the area - and their periods, we have defined a wave climate model based on the construction of refraction diagrams. The resulting model of sediment transport, as obtained by numerical modelling from the refraction diagrams, taking into consideration the angle of approach and waves heights along the 10-m isobath, was capable of reproducing the patterns of sediment dispersion provided by geomorphic indicators of the longshore drift. All this coastal region, approximately 900 km in length, is...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Littoral drift; Wave refraction; Numerical modelling; Coastal Quaternary evolution; Northeastern Brazilian coast.
Ano: 2002
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652002000300012