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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Dissolved Oxygen Hydrodynamic Simulation using coupling wing-bottom Shallow Water and Contaminant Transport Formulation in Asuncion Bay
Submission Author:
Marcos Gabriel Caceres Romero , Central , Paraguay
Co-Authors:
Marcos Gabriel Caceres Romero, Aida Ramona Ortiz
Presenter: Marcos Gabriel Caceres Romero
doi://10.26678/ABCM.ENCIT2022.CIT22-0560
Abstract
The Asuncion Bay is a naturally occurring water body with industrial and historical significance located in the city of Asuncion. Due to its geographical characteristics, it is a stopover for migratory birds, and nowadays is a protected wilderness area under the ecological reserve management category being part of the Western Hemisphere Shorebird Reserve Network. Unfortunately, due to the disorganized city growth and the lack of effective norms to process the waste disposal, the bay is highly contaminated. This work proposes a computational simulator to predict the hydrodynamics, the concentration of Dissolved Oxygen (DO), and the Biochemical Oxygen Demand (BOD) of a reactive substance discharged in the Asuncion Bay. To this end, we obtain the mesh of the bay by using bathymetric data and formulate the transport of a reactive scalar from the Shallow Water equations (SWE). The hydrodynamic model includes the bottom and wind shear stress, as well as the reactive terms of the DO and BOD transport equation, which are coupled. In addition, appropriate boundary conditions are imposed for coupling the interaction between the Paraguay River and the bay itself. The Numerical simulation was performed in OpenFOAM which is based on the finite volume method to solve the model equations. The solver is numerically verified, checking the correctness of resolution of the equations, and spatial-temporal convergence for several mesh refinements. Simulation results are contrasted with measurements of water speed and instrumental analysis of in situ samples obtained from the water bay. The comparisons corroborate that the simulator captures qualitatively the dynamics of the bay, predicts the contaminant distribution in space and time in terms of DO (which is a parameter of aquatic life of a water body), and identifies critical stagnation regions in the bay. These are valuable information for the decision-makers to avoid eutrophication regions and elaborate precise mitigation actions for the health natural conservation of the Asuncion Bay.
Keywords
Shallow Water Equations (SWE), Hydrodinamic Modeling, Dissolved Oxygen (DO), OpenFOAM, Asuncion Bay
