Étude sédimentologique de sites de dépôt de matériaux de dragage dans le fleuve Saint-Laurent. I. Modélisation numérique tridimensionnelle du panache de dispersion des sédiments retenus dans la colonne d'eau

1994 ◽  
Vol 21 (6) ◽  
pp. 1025-1036
Author(s):  
Ali Khelifa ◽  
Yvon Ouellet
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Water Discharge ◽  
Three Dimensional ◽  
Element Formulation ◽  
Modélisation Numérique ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
La Madeleine ◽  
St Lawrence River

Within the sedimentological study of disposal sites of dredged materials along the St. Lawrence River between Sorel and Saint-Pierre-les-Becquets, a three-dimensional numerical model (SED3D) has been developed to reproduce the dispersion of sediments maintained in the water column during an open-water discharge operation. This model is based on the extension of the Douglas–Wang finite element formulation to discretize the steady three-dimensional advection–diffusion equation. The space discretization is quadratic using 20 nodes hexahedron elements (H20). Results of SED3D model applied to Cap-de-la-Madeleine disposal site show that suspended sediments settle in a domain less than 200 m of the disposal point by 50 m and so they can not reach the seaway. The qualitative validity of these results was demonstrated by the analysis of some sediment samples taken in the St. Lawrence River at Cap-de-la-Madeleine. Key words: dredging, sediments, St. Lawrence River, advection–diffusion, numerical model, Douglas–Wang, finite element.

Étude de la réouverture de la lagune du Havre aux Basques. II. Modélisation numérique du processus de mélange des eaux

1995 ◽  
Vol 22 (1) ◽  
pp. 72-79
Author(s):  
A. Khelifa ◽  
Y. Ouellet ◽  
J.-L. Robert
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Transport Model ◽  
Numerical Study ◽  
Time Discretization ◽  
Element Formulation ◽  
Modélisation Numérique ◽  
Advection Diffusion ◽  
Space Discretization ◽  
Triangular Elements

This paper, the second of a series, presents the results of a numerical study of the advection–diffusion water mixing process between the Havre aux Basques lagoon and the Gulf of St. Lawrence, after the proposed reopening of the lagoon. In this study, the reopening scheme of the inlet, which has been closed in 1957, is analyzed by using a horizontal two-dimensional numerical model. The transport model is based on the Douglas–Wang finite element formulation for a space discretization. The approximation is quadratic, using six-node triangular elements. The semi-implicit Crank–Nicholson scheme is used for a time discretization. The results show that after reopening the lagoon, mixing may take between 5 and 22 days for a diffusion coefficient considered constant throughout the region and varying from 5 to 500 m2/s. Key words: lagoon, Havre aux Basques, advection–diffusion, mixing, numerical model, finite element, Douglas–Wang.

scholarly journals NUMERICAL MODEL OF 3D MORPHODYNAMIC AFTER OFFSHORE NOURISHMENT

2011 ◽  
Vol 1 (32) ◽  
pp. 55 ◽  
Author(s):  
Masamitsu Kuroiwa ◽  
Yoko Shibutani ◽  
Yuhei Matsubara ◽  
Takayuki Kuchiishi ◽  
Mazen Abualtyef
Keyword(s):  
Numerical Model ◽  
Diffusion Equation ◽  
Suspended Sediment Concentration ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Sand Material

A three-dimensional model of morphodynamics after offshore nourishment was developed. In the presented model, the 3D beach evolution model that is not only after nourishment but also taking into account the nourishment process of injected sand material. In order to consider the injected process of sand, the computation using the advection-diffusion equation for suspended sediment concentration was adapted in the model. The presented model was applied to an idealized beach with two groins in order to investigate the performance of the model, and then, the model was applied to a field observation result for shoreface nourishment carried out at the Egmond aan Zee in the Netherlands. Finally, the applicability of the presented model was discussed from the computed results.

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