Date of Award
Ph.D. in Engineering Science
Mustafa S. Altinakar
In this study, a three-dimensional numerical model of multiple-sized sediment transport under current and waves is developed. The coastal circulations are described by a three-dimensional hydrodynamic model, which is governed by the three-dimensional phase-averaged shallow water flow equations coupled with wave radiation stresses. Methods are also developed to determine the bed shear stress due to current only, waves only, and coexistence of current and waves, accounting for the nonlinear interaction of the current and waves on bed shear stresses. Meanwhile, empirical formulas for bed-load transport capacity, suspended-load transport capacity, and near-bed suspended-load concentration under current and waves are established for multiple-sized sediments. These formulas are used to close the sediment transport model. The flow and sediment transport equations are solved using a finite volume method on non-staggered grid. The computational mesh is composed of quadtree rectangular grid on the horizontal plane and sigma coordinate in the vertical direction. The SIMPLEC algorithm with Rhie and Chow's momentum interpolation is used to couple the flow velocity and water level. A coupled solution procedure is used to solve the discretized sediment transport, bed change and bed material sorting equations together. The empirical formulas for bed-load and suspended-load transport rates and the near-bed suspended-load concentration have been tested intensively using a large volume of single- and multiple-sized sediment transport data under current and waves. Statistics show that more than 50% of the cases are predicted within a factor of 2 of the measured values and more than 80% of the cases are within a factor of 5. The hydrodynamic model has been validated using two laboratory cases and two field cases, which demonstrate the reliability of the flow model and its coupling with wave model. The multiple-sized sediment transport sediment transport model has been validated using three laboratory cases and one field case. The predications of the model are in good agreement with the measurements. Sensitivity analyses have also been conducted for the bed friction coefficient, suspended-load scale factor, Schmidt Number, bed-load adaptation length, and roughness height constant. The developed sediment model has been demonstrated its capability of predicting morphologic behavior through the test cases.
Lin, Qianru, "Three-Dimensional Numerical Modeling Of Multiple-Sized Sediment Transport Modeling Under Current And Waves" (2014). Electronic Theses and Dissertations. 440.
Emphasis: Computational Hydroscience