Date of Award
Ph.D. in Engineering Science
Cristiane Q. Surbeck
A two-dimensional depth-integrated model is developed for simulating wave-averaged hydrodynamics and nonuniform sediment transport and morphology change in coastal waters. The hydrodynamic model includes advection, wave-enhanced turbulent mixing and bottom friction; wave-induced volume flux; wind, atmospheric pressure, wave, river, and tidal forcing; and Coriolis-Stokes force. The sediment transport model simulates nonequilibrium total-load transport, and includes flow and sediment transport lags, hiding and exposure, bed material sorting, bed slope effects, nonerodible beds, and avalanching. The flow model is coupled with an existing spectral wave model and a newly developed surface roller model. The hydrodynamic and sediment transport models use finite-volume methods on a variety of computational grids including nonuniform Cartesian, telescoping Cartesian, quadrilateral, triangular, and hybrid triangular/quadrilateral. Grid cells are numbered in an unstructured one-dimensional array, so that all grid types are implemented under the same framework. The model uses a second-order fully implicit temporal scheme and first- and second-order spatial discretizations including corrections for grid non-orthogonality. The hydrodynamic equations are solved using an iterative pressure-velocity coupling algorithm on a collocated grid with a momentum interpolation for inter-cell fluxes. The multiple-sized sediment transport, bed change, and bed material sorting equations are solved in a coupled manner but are decoupled from the hydrodynamic equations. The spectral wave and roller models are calculated using finite-difference methods on nonuniform Cartesian grids. An efficient inline steering procedure is developed to couple the flow and wave models. The model is verified using seven analytical solution cases and validated using ten laboratory and five field test cases which cover a wide range of conditions, time and spatial scales. The hydrodynamic model simulates reasonably well long wave propagation, wetting and drying, recirculation flows near a spur-dike and a sudden channel expansion, and wind- and wave generated currents and water levels. The sediment transport model reproduces channel shoaling, erosion due to a clear-water inflow, downstream sediment sorting, and nearshore morphology change. Calculated longshore sediment transport rates are well simulated except near the shoreline where swash processes, which are not included, become dominant. Model sensitivity to the computation grid and calibration parameters is presented for several test cases.
Sanchez, Alejandro, "An Implicit Finite-Volume Depth-Integrated Model For Coastal Hydrodynamics And Multiple-Sized Sediment Transport" (2013). Electronic Theses and Dissertations. 942.
Emphasis: Computational Hydroscience