Identifier

etd-06142007-084318

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Hydrodynamic models of a hypothetical Mississippi river diversion near Empire, LA are constructed using two popular finite element codes RMA2 and ADCIRC. In a series of simulations eddy viscosity parameters and bottom friction parameters are varied. Constant boundary conditions, discharge inflow and elevation outflow, are applied and water surface elevation and velocity solutions at fully developed flow are taken as steady-state results. A particle tracking code is developed and applied to the velocity solutions to aid in flow field comparisons. The results elucidate the model sensitivities to the varied parameters, and also provide for a comparison of the two different models. Both models show similar sensitivities to the eddy viscosity and bottom friction parameters. It is shown for both models that there is a minimum value of eddy viscosity that will produce stable results. Above this value cross-channel velocity gradients are flattened throughout the domain as the eddy viscosity is increased leading to results which may under-predict peak channel velocities. Particle tracking simulations show that the flow field is not significantly affected by varying the eddy viscosity. Increasing the bottom friction coefficients causes an increase in Water Surface Elevation(WSE) gradient across the domain. Steeper WSE gradients lead to small changes in the overall flow distribution, and median residence time, as can been seen with particle tracking results. Also increased WSE due to increased bottom friction causes model specific differences in the flow field due to the application of different wet/dry algorithms in the different models.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Clinton S. Willson

DOI

10.31390/gradschool_theses.660

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