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1.
A three-dimensional finite-difference hydrodynamic model has been developed using σ-coordinate for the vertical dimension. An explicit scheme for temporal integration and a staggered grid for spatial discretization have been adopted. The model has been tested against analytical or literature cases for wind and tide induced circulation. Results are in good agreement both with analytical solutions under idealised conditions and with results from the model of Shankar et al. (1996). 相似文献
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Anne Levasseur Lei Shi Neil C. Wells Duncan A. Purdie Boris A. Kelly-Gerreyn 《Estuarine, Coastal and Shelf Science》2007,73(3-4):753-767
A three-dimensional hydrodynamic model has been developed to simulate water mass circulation in estuarine systems. This model is based on the primitive equation in Cartesian coordinates with a terrain-following structure, coupled with a Mellor–Yamada 2.5 turbulence scheme. A fractional-step method is applied and the subset of equations is solved with finite volume and finite element methods. A dry–wet process simulates the presence of the tidal flat at low water. River inputs are introduced using a point-source method. The model was applied to a partially mixed, macrotidal, temperate estuary: Southampton Water, UK. The model is validated by comparisons with sea surface elevation, ADCP measurements and salinity data collected in 2001. The mean spring range 2(M2 + S2) and the mean neap range 2(M2 − S2) are modelled with an error relative to observation of 12 and 16%, respectively. The unique tidal regime of the system with the presence of the ‘young flood stand’ corresponding to the slackening conditions occurring at mid flood and ‘double high water’ corresponding to an extension of the slackening conditions at high tide is accurately reproduced in the model. The dynamics of the modelled mean surface and bottom velocity closely match the ADCP measurements during neap tides (rms of the difference is 0.09 and 0.01 m s−1 at the bottom and at the surface, respectively), whereas at spring the difference is greater (rms of the difference is 0.25 and 0.20 m s−1 at bottom and surface, respectively). The spatial and temporal variation of the degree of stratification as indicated by salinity distributions compares well with observations. 相似文献
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A three-dimensional semi-implicit finite volume numerical model has been developed and applied to study tidal circulation and salinity stratification in the region of Oujiang River Estuary, China. The model employs horizontally unstructured grids and boundary-fitted coordinate system in the vertical direction. Governing equations consisting of continuity, momentum, and transport equations are all solved in the integral form of the equations, which provides a better representation of the conservative laws for mass, momentum, and transport in the coastal region with complex geometry and bottom bathymetry. The model performance was firstly quantified with skill assessment statistics on the choice of different parameters and validated with observed tidal elevation, current velocity, direction and salinity data over a spring–neap tidal cycle collected in 2006. Numerical results show that the model with wetting–drying capability successfully simulated the tidal currents and salinity fields with a reasonable accuracy and indicate that the Oujiang River Estuary is a macrotidal estuary with strong tidal mixing. In addition, the model results also show that the Oujiang River Estuary is a well-mixed estuary during spring tide. Then, the numerical simulations were performed to compare the hydrodynamic process and salinity distribution before and after a river training, which was conducted by blocking the south branch of the Oujiang River mouth. The results reveal that with the only north access to the sea, the influence of the blocking project on the flood discharge capacity is limited and the incremental velocity is beneficial to the navigation channel maintenance, although it will cause some scour to the embankment. Furthermore, the redistribution of tidal prism passing in or out the north branch makes a little severe salinity intrusion during high tide or low tide. However, the salinity intrusion is still within acceptable range, although it can cause some adverse effect on water intaking of production and life. The variations of salinity levels in Yueqing Bay situated at the north of the river mouth are not obvious, so the blocking project will not bring damage to local aquiculture. However, significant changes of salinity happen inside or outside of the south branch, so enough attention need to be paid to the changes of environment caused by the salinity variation after the blocking project. Overall, by weighing advantages and disadvantages of the blocking project, it is feasible and the model can be considered as a tool for managing and studying estuarine circulation. 相似文献
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A three-dimensional density field associated with mesoscaie unstable waves generated by the 3-D, primitive-equation model (Wang and Ikeda, 1996) is provided to the quasi-geostrophic pressure tendency and ω-equations, and to the (ageostrophic) Q-vector equation. Diagnostic analyses, analogous to the approaches in meteorology: ω-equation and Q-vector method, are for the first time developed to examine the mesoscaie dynamical processes and mechanisms of the unstable waves propagating in the mid-latitude ocean. The weaknesses and strengths of these two diagnostic approaches are evaluated and compared to the model results. The Q-vector method is then recommended to diagnose the vertical motion associated with the mesoscaie dynamics from a hydrographic CTD (conductivity-temperature-depth) array, while the quasi-geostrophic equations produce some small-scale features (errors) in the diagnosed fields. 相似文献
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AnADItechniqueforsolvingthree-dimensionalcoastalcirculationYangLianwu1,*andJoseOzer2(ReceivedNovember27,1996;acceptedDecember... 相似文献
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A comparison of two three-dimensional numerical modeling systems for tidal elevations and velocities in the coastal waters is presented. The two modeling systems are: (1) the Princeton Ocean Model (POM) and (2) the MIKE 3 flow model. The model performance results for Singapore's coastal waters show that the predicted tidal elevations from the two hydrodynamic modeling systems are almost identical and are in very good agreement with field measurement data. The simulated tidal current velocities match well with field measurement data at the selected stations, but it seems that the POM provides the slightly better simulation, compared to the MIKE 3 flow model. The depth profiles of the velocities obtained from the two modeling systems may be greatly different at some time, due to the vertical diffusion coefficient calculated from different turbulent sub-models in the two modeling systems. The POM generally predicts larger peak tidal velocities. The maximum speed differences for the model results from the two modeling systems occur in the top and differ from time to time and from location to location, reaching up to 20%. 相似文献
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We generalize the problem of evaluation of currents caused by the action of breeze winds to the three-dimensional case. In
the “solid-lid” approximation, the problem is reduced to the numerical solution of a two-dimensional equation for the integral
current function (with complex-valued coefficients) with subsequent evaluation of the components of current velocity according
to analytic formulas. The breeze is specified as acting in a narrow coastal strip in the form of a zonal wind. The three-dimensional
structure and the variations of currents near the west boundary of the Kerch Strait as functions of time are studied in detail. 相似文献
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Baroclinic terms have been implemented in a three-dimensional fully hydrodynamic model developed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] modifying its momentum equations to account for density gradients and utilizing the scalar (salinity, temperature, etc.) conservation equation (SCE) and a state equation for the calculation of density. In the solution of advection-diffusion terms of the governing Navier-Stokes equations (NSE) and SCE, a symmetric splitting method was applied to ensure the long-term stability of simulations. Correction terms proposed by Ruddic et al. (1995) were applied to SCE to ensure the conservation of the scalar quantity. In the presence of baroclinic terms, the zero gradient pressure in the vertical direction in the vicinity of surface and bottom boundaries assumed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] created spurious currents. This problem was solved by assuming a hydrostatic pressure variation at those boundaries. The ability of extended model was validated by comparing its results with an experimental test case. The simulation of hydrodynamic and salt intrusion at Anzali Port located at the southern coasts of Caspian Sea in Iran was carried out by the model with both barotropic and baroclinic modes. The simulated results with baroclinic mode show a better agreement with measured data as compared to the results of barotropic mode that clearly demonstrate the significance of baroclinic terms in the simulation of cyclic intrusion of salt wedge into the Port Basin. 相似文献
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Athree-dimensionaloceangeneralcirculationmodelformesoscaleeddies──ⅠMeandersimulationandlineargrowthrate¥WangJiaandMotoIkeda(R... 相似文献
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A hydrothermodynamic model of a multilayer ocean, incorporating the upper mixed layer (UML) is described. The model is based on a system of primitive equations integrated within each layer. All layers are assumed to be horizontally-inhomogeneous, however, the density in each thermocline layer changes within the limits determineda priori by the prescribed basic stratification. It is assumed that the layers may outcrop. Results of the numerical experiment on subduction simulation (downwelling of UML waters toward the main thermocline layers) are given.Translated by V. Puchkin. 相似文献
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Three-dimensional hydrodynamic model of Xiamen waters 总被引:3,自引:0,他引:3
Abstract-A semi-implicit and Eulerian-Lagrangian finite difference method for three-dimensionalshallow flow has been extended to a more complete system of equations incorporating second-momentturbulence closure model and transport equations of salinity and temperature. The simulation for flood-ing and drying of mudflats has been improved. The model is applied to Xiamen waters. Based on exten-sive survey data, water level elevation, temperature and salinity field along the eastern open boundaryand at the Jiulong River inlets and runoffs are analyzed, specified and calibrated. The computed resultsshow good agreement with the measured data, reproduce flooding, emergence of large and complexmudflat region. 相似文献
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《Marine Chemistry》2007,103(1-2):15-29
In this paper, the design, calibration and application of an integrated geochemical–hydrodynamic model are described. The model comprises three parts: A hydrodynamic submodel that was adopted from a depth-averaged, semi-implicit hydrodynamic model, a geochemical submodel based on equilibrium partitioning of chemicals between aqueous and particulate phases, and a particle dynamic submodel that simulates resuspension, transport and settling of suspended particulate matter (SPM). The integrated model was implemented in San Diego Bay (SDB), a heavily urbanized, semi-closed mesotidal embayment. A series of model calibrations were carried out based on observations on salinity, polychlorinated biphenyls (PCBs) and SPM. Salinity calibrations indicated that only 15% of precipitation in the drainage area of SDB could reach the bay, presumably due to the dams on the tributary rivers. Steady-state calibrations of PCBs based on fixed concentrations at known ‘hot spots’ have reproduced observed PCB concentrations in both the dissolved and particulate phases. SPM calibrations showed that shipping-induced resuspension produce more SPM than natural processes. Based on the calibrated model, the annual transport of PCBs out of SDB was estimated to be 3.85 kg (3.5 kg and 0.35 kg in the dissolved and particulate phases, respectively), much higher than the previous estimates based on steady-state assumptions. It was also found out that only a small portion of the fine sediment exported from SDB was derived from riverine input. This model can be applied to the studies of the transport and fate of other chemical species. It can be transplanted to other coastal areas as well. The integrated model represents a novel framework in which geochemical processes in coastal environments can be investigated on a truly dynamic basis. 相似文献
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A three-dimensional finite element model is used to investigate the formation of shallow-water eddies in the wake of Rattray Island (Great Barrier Reef, Australia). Field measurements and visual observations show that stable eddies develop in the lee of the island at rising and falling tides. The water turbidity downstream of the island suggests the existence of strong upwelling that would be responsible for carrying bed sediments up to the sea surface. We first propose to look at the upwelling velocity and then use the theory of the age to diagnose vertical transport. The water age is defined as the time elapsed since particles of water left the sea bottom, where the age is prescribed to be zero. Two versions of this diagnosis are considered. Although the model predicts upwelling within the eddies, it is not sufficiently intense to account for vertical transport throughout the water column during the life span of the eddies. As mesh resolution increases, this upwelling does not intensify. However, strong upwelling is then resolved off the island's tips, which is confirmed by the results obtained with the age. This study also shows that the finite element method, together with unstructured meshes, performs well for representing three-dimensional flow past an island. 相似文献
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A hydrothermodynamic model based on the traditional system of differential equations is discussed. The model uses conservative finite-difference schemes based on the methods of identifying the barotropic and baroclinic velocity components and on the complete inversion of the dynamic operator. Test computations for the Black Sea basin have been conducted.Translated by Vladimir A. Puchkin. 相似文献
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The hydrodynamic force model for pipelines presented includes flow history effects (wake effects) and time dependence in the force coefficients. These two features in the model were necessary to obtain satisfactory agreement between model predictions and full scale field measurements of pipeline forces. Conventional force models which represent adaptations of Morison's equation with ambient velocity and constant coefficients give predictions which for the lift component of the force in particular are in very poor agreement with the measurements. The parameters in the new model have been estimated on the basis of the full scale measurements and reflect a wide range of flow conditions. The model can be used in pipeline on-bottom stability design calculations for regular or irregular waves. 相似文献