scholarly journals Comparison of computational efficiency of explicit and implicit schemes for the sediment transport problem in coastal zones

2015 ◽  
pp. 328-338
Author(s):  
А.И. Сухинов ◽  
Е.А. Проценко ◽  
А.Е. Чистяков ◽  
С.А. Шретер
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Three Dimensional ◽  
Critical Shear Stress ◽  
Physical Parameters ◽  
Variable Geometry ◽  
Coastal Zones ◽  
Sediment Transport Model ◽  
Level Elevation ◽  
Wind Flows

Рассмотрена нестационарная пространственно-двумерная модель транспорта наносов в прибрежной зоне водоемов, учитывающая следующие физические параметры и процессы: пористость грунта; критическое значение касательного напряжения, при котором начинается перемещение наносов; турбулентный обмен; динамически изменяемую геометрию дна и функцию возвышения уровня; ветровые течения; трение о дно. Построены и программно реализованы на кластере распределенных вычислений пространственно-трехмерная модель гидродинамики в прибрежной зоне водоемов и модель транспорта взвешенных частиц. Приведены результаты численных экспериментов. An unsteady spatial two-dimensional sediment transport model in coastal zones is considered. The model takes into account the following physical parameters and processes: the soil porosity; the critical shear stress at which the sediment displacement begins; the turbulent exchange; the dynamically variable geometry of the bottom and the level elevation function; the wind flows; and the bottom friction. A spatial three-dimensional hydrodynamic model for coastal zones and a transport model for suspended particles are proposed and implemented on a computing cluster. Some numerical results are discussed.

scholarly journals 3 Dimensional Modeling of Advection-Diffusion Equation

2019 ◽  
Author(s):  
Amin Ilia
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Transport Model ◽  
Three Dimensional ◽  
Water Levels ◽  
Dynamics Simulation ◽  
Advection Diffusion ◽  
Sediment Transport Model ◽  
Time Splitting ◽  
2D Model

Estimation of flows and sediment transport is challenging as many complexes and interacting physical phenomena need to be accounted for. In this research, a coupled two-dimensional finite volume flow model and a three-dimensional sediment transport model were developed in Fortran. In this model, the depth-integrated current vectors and water level were computed by 2D shallow water equations as the 2D model is computationally much faster than the 3D model. The depth-integrated current vectors were distributed in depths using a logarithmic current distribution equation, log of the wall. These distributed velocities and simulated water levels were used for three-dimensional sediment transport model which is generated using the same scheme. A 3D sediment transport model was preferred over a 2D model as 3D sediment model can estimate vertically diffusion of sediment mass from bedload to suspended sediment load which significantly improves the prediction of morphology evolutions.In order to discretize each subset of equations with the best-suited method, I utilized a time-splitting technique. As a result, I applied the second-order Fromm scheme which was found the best method for solving advection terms and semi-implicit forward time central space method which was found the best method for solving diffusion terms. The time-splitting scheme also reduced the complicity, therefore, the solution became simple and attractive to apply. For developing the sediment transport model, I applied this advection-diffusion concept to estimate the distribution of suspended sediment concentration and the Van Rijn (1981) scheme for the estimation of bedload sediment transport. As it’s very important to estimate and predict this phenomenon accurately, I compared the model with a lab trench experiment and the model results were in agreement with lab experiments. It was shown that the model could accurately simulate sedimentation on the downsloping (deceleration) section and erosion on the upsloping (acceleration) section of a marine trench. This would cause lateral movement of the channel toward the current direction. Being capable of accurate sediment transport and morphological dynamics simulation in this complex setting, this model is validated to be applied to other marine problems.

scholarly journals A Three-Dimensional Flow and Sediment Transport Model for Free-Surface Open Channel Flows on Unstructured Flexible Meshes

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 18 ◽  
Author(s):  
Yong Lai ◽  
Kuowei Wu
Keyword(s):  
Free Surface ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
Open Channel ◽  
Transport Model ◽  
Three Dimensional ◽  
Suspended Sediment Transport ◽  
Open Channel Flows ◽  
Sediment Transport Model ◽  
Flow And Sediment Transport

Three-dimensional (3D) hydrostatic-pressure-assumption numerical models are widely used for environmental flows with free surfaces and phase interfaces. In this study, a new flow and sediment transport model is developed, aiming to be general and more flexible than existing models. A general set of governing equations are used for the flow and suspended sediment transport, an improved solution algorithm is proposed, and a new mesh type is developed based on the unstructured polygonal mesh in the horizontal plane and a terrain-following sigma mesh in the vertical direction. The new flow model is verified first with the experimental cases, to ensure the validity of flow and free surface predictions. The model is then validated with cases having the suspended sediment transport. In particular, turbidity current flows are simulated to examine how the model predicts the interface between the fluid and sediments. The predicted results agree well with the available experimental data for all test cases. The model is generally applicable to all open-channel flows, such as rivers and reservoirs, with both flow and suspended sediment transport issues.

Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model

2008 ◽  
Vol 34 (10) ◽  
pp. 1284-1306 ◽  
Author(s):  
John C. Warner ◽  
Christopher R. Sherwood ◽  
Richard P. Signell ◽  
Courtney K. Harris ◽  
Hernan G. Arango
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Three Dimensional ◽  
Sediment Transport Model ◽  
Coupled Wave

scholarly journals PREDICTION ON MORPHOLOGICAL RESPONSE OF DREDGED SAND-BORROW PITS

2011 ◽  
Vol 1 (32) ◽  
pp. 74 ◽  
Author(s):  
Qimiao Lu ◽  
Robert B. Nairn
Keyword(s):  
Sediment Transport ◽  
Environmental Impacts ◽  
Transport Model ◽  
Atlantic Coast ◽  
Coastal Zones ◽  
Morphological Response ◽  
Concept Model ◽  
Simple Concept ◽  
Sediment Transport Model

Dredged pits in coastal zones are generally required for sand borrows for beach nourishment. The morphological response of borrow pits is important to evaluate future environmental impacts and potential impacts to adjacent seabed infrastructure such as pipelines. This paper will present the development of a simple concept model for the prediction of morphological response of dredged pits. A 3D hydrodynamic and sediment transport model was applied to verify the developed simple concept model. The case study for a sand-borrow pit on the offshore of Louisiana at the Atlantic coast of USA will be updated. The strengths and limitations of the developed model will be also discussed.

2D multi-layer hydrodynamic and sediment transport modelling in a tidal estuary

2020 ◽  
Author(s):  
Kai-Yi Bai ◽  
Jiing-Yun You
Keyword(s):  
Sediment Transport ◽  
Shallow Water ◽  
Finite Volume ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Computational Domain ◽  
Operation Rules ◽  
Sediment Transport Model

<p>This study developed a multi-layer hydrodynamic and sediment transport model for simulating tides and the estuarine flows. The flow circulation in an estuary shows complicated mixing and stratification patterns due to the combined effects from currents and tides. This kind of issues becomes more important in Taiwan in line with the more and more frequent sediment flushing operation which led to high sediment concentration flow at the estuary. In some applications,  three-dimensional (3D) models solving full Navier-Stokes equations were used. However, the extremely high computational cost, especially for the large-scale environmental problems, is always a serious concern. In the past years, continuous efforts have been devoted to the development of efficient quasi-three-dimensional models under hydrostatic and Boussinesq assumptions. Following the same state-of-the-art modelling strategy, this study develops a multi-layer shallow-water and sediment transport model with finite volume method. In this model, a terrain following coordinate with high local resolution is used to vertically divide the computational domain into multiple layers to better addressing bottom topography and velocity profile. Our model is rigorously validated against several benchmark cases including winddriven circulation, subcritical flow over a hump, tidal wave propagation, and sediment transport. The grid convergence test and accuracy both are in good agreement with analytical solutions. Subsequently, the model is applied to investigate the estuary dynamics and sediment transport under different conditions, e.g., flow discharges, bottom slopes, wind shears and tidal variations. Overall, the results show a relationship between flow conditions and sediment transport. Later, some scenarios for various upstream inflow and sediment concentration will be examined to assess the reservoir operation rules. </p><p><strong>Keywords: shallow water, sediment transport, multi-layer, hydrostatic, Boussinesq Assumption, a finite volume characteristics (FVC) method </strong><br> </p><p><br> <br> <br><br> </p>

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