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THREE DIMENSIONAL MOBILE BED DYNAMICS FOR SEDIMENT TRANSPORT MODELING DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Sean O’Neil, B.S., M.S. ***** The Ohio State University 2002 Dissertation Committee: Approved by Professor Keith W. Bedford, Adviser Professor Carolyn J. Merry Adviser Professor Diane L. Foster Civil Engineering Graduate Program c Copyright by Sean O’Neil 2002 ABSTRACT The transport and fate of suspended sediments continues to be critical to the understand- ing of environmental water quality issues within surface waters. Many contaminants of environmental concern within marine and freshwater systems are hydrophobic, thus read- ily adsorbed to bed material or suspended particles. Additionally, management strategies for evaluating and remediating the effects of dredging operations or marine construction, as well as legacy pollution from military and industrial processes requires knowledge of sediment-water interactions. The dynamic properties within the bed, the bed-water column inter-exchange and the transport properties of the flowing water is a multi-scale nonlin- ear problem for which the mobile bed dynamics with consolidation (MBDC) model was formulated. A new continuum-based consolidation model for a saturated sediment bed has been developed and verified on a stand-alone basis. The model solves the one-dimensional, vertical, nonlinear Gibson equation describing finite-strain, primary consolidation for satu- rated fine sediments. The consolidation problem is a moving boundary value problem, and has been coupled with a mobile bed model that solves for bed level variations and grain size fraction(s) in time within a thin layer at the bed surface. The MBDC model represents the first attempt to unify bed exchange and accounting mechanisms with vertically varying bed properties under a single mechanistic framework. ii A suspended sediment transport solver, with parameterizations for noncohesive grain size settling velocity, erosion and depositions source sink terms has been extended to in- clude parameterizations for cohesive grain sizes. Further, the consolidation model has been integrated into the mobile bed modeling framework. The new fine-grained sediment trans- port model, MBDC, was configured to simulate the flow, transport and bottom evolution within an expansion channel serving as an idealized conical estuary. MBDC model results, are compared with model results from literature, demonstrating qualitative agreement and model efficacy. The MBDC model approach, though requiring more site specific data for auxiliary parameterizations, yields a more complete physical and dynamic description of bed sediment transport processes. iii To my dearest friend and wife Chen Hui. You have inspired me to be more than I thought I could ever be. iv ACKNOWLEDGMENTS I would like to acknowledge the enthusiastic help from my friends and colleagues at the Great Lakes Forecasting System Laboratory, Dr. Philip Chu, Dr. David Welsh, Takis and Vasso Velisariou, Guo Yong, and especially Dr. Jennifer Shore and Heather Smith. Past members of the GLFS Lab and the “Dirt Group”, who also helped me were Drs. David Podber, John Kelley, James Yen, W. K. Yeo, and my brothers Dr. Jongkook Lee, Rob Van Evra and Dr. Onyx Wai. I would also like to mention some of the faculty and staff members who made a differ- ence during my stay at OSU including Dr. Robert Sykes, Dr. Bill Wolfe, Dr. Vince Ricca, Dr. Ellen MacDonald and especially Ray Hunter. I would also like to thank my Disserta- tion Reading Committee members, Dr. Carolyn Merry and Dr. Diane Foster both of whom offered much support freely and enthusiastically. I acknowledge the help of my HydroQual colleagues and friends including Jim Hallden, Luca Liberti, Nicholas Kim, Dr. Pravi Shrestha, Dr. Alan Blumberg and many others. I would also like to thank my very good friend David Driscoll. I would like to thank my sisters Mary and Colleen and my father Pat who never doubted me. Most importantly, I recognize my advisor Professor Keith W. Bedford; I will never forget him for his guidance and support. v VITA 1987 .......................................B.S. Physics, University of Minnesota, Minneapolis, MN 1993 .......................................M.S. Civil Engineering, The Ohio State University, Columbus, OH 1999-2001 ..................................Engineer, HydroQual, Inc., Mahwah, NJ 1991-1999,2001-present . ....................Graduate Research and Teaching Asso- ciate, Civil and Environmental Engineer- ing and Geodetic Science, The Ohio State University, Columbus, OH PUBLICATIONS Wai, O. W.-H., Y. S. Xiong, S. O’Neil and K. W. Bedford (2001). “Parameter Estima- tion for Suspended Sediment Transport Processes”, The Science of the Total Environment, 226(1-3), 49-59. O’Neil, S. and D. P. Podber (1997). “Sediment Transport Dynamics in a Dredged Tribu- tary,” Int. Conf. Estuarine and Coastal Modeling, eds. A. Blumberg and M. Spaulding, 5, 781-791. O’Neil, S., K. W. Bedford and D. P. Podber (1996). “Storm-Derived Bar/Sill Dynamics in a Dredged Channel,” Proc. Int. Conf. Coastal Eng., ASCE, 25, 4289-4299. Lee, J., S. O’Neil, K. W. Bedford and R. E. Van Evra (1994). “A Bottom Boundary Layer Sediment Response to Wave Groups,” Proc. Int. Conf. Coastal Eng., American Society of Civil Engineers, 24, 1827-1837. Wai, O. W.-H., K. W. Bedford and S. O’Neil (1994). “Principal Components Time Spectra of Suspended Sediment in Random Waves,” Coastal Dynamics ’94, ASCE, Barcelona, 296-305. vi Bedford, K. W., O. W.-H. Wai, S. O’Neil and M. Abdelrhman (1991). “Operational Pro- cedures for Estimating Bottom Exchange Rates,” in Hydraulic Engineering, Ed. R. Shane, American Society of Civil Engineers, 465-470. Zhang, S., D. J. S. Welsh, K. W. Bedford, P. Sadayappan and S. O’Neil (1998). “Cou- pling of Circulation, Wave and Sediment Models,” Technical Report CEWES MSRC/PET TR/98-15. The Ohio State University, 32 pp. Bedford, K. W., S. O’Neil, R. E. Van Evra and J. Lee (1994). “Ohio State University Measurements at SUPERTANK,” in SUPERTANK Laboratory Data Collection Project, Volume 1. Eds. Nicholas C. Kraus and Jane McKee Smith. U.S. Army Corps of Engineers, Waterways Experiment Station, Technical Report CERC-94-3, pp. 152-184. O’Neil, S. (1993). Comparison of Sediment Transport Due to Monochromatic and Spec- trally Equivalent Random Waves. MS thesis, The Ohio State University, Columbus, Ohio. Bedford, K. W., S. O’Neil, R. E. Van Evra and J. Lee (1993). “The Ohio State University Offshore ARMS Data - Boundary Layer, Entrainment and Resuspension: Overview plus Appendix,” Project Report, U.S. Army Corps of Engineers, Vicksburg, MS, 141 pp. FIELDS OF STUDY Major Field: Civil Engineering Studies in: Models in Water Resources Engineering Sediment Transport Phenomena Prof. Keith W. Bedford Coastal Engineering Applied Mathematics/Computational Science Profs. G. Baker, E. Overman Aerospace Engineering Prof. R. Bodonyi vii TABLE OF CONTENTS Page Abstract . ..................................... ii Dedication . ..................................... iv Acknowledgments . .............................. v Vita........................................... vi List of Tables . ..................................... xi List of Figures . ..................................... xii Chapters: 1. Introduction . .............................. 1 2. Sediment Consolidation - Theoretical and Numerical Models . ..... 23 2.1 One-Dimensional, Large Strain, Self-Weight, Primary Consolidation . 32 2.1.1 The Governing Equation . ................ 32 2.1.2 Force Balance . ....................... 35 2.1.3 Material Equilibrium . ....................... 35 2.1.4 Governing Equation . ....................... 37 2.1.5 Boundary Conditions ....................... 38 2.1.6 Initial Conditions . ....................... 41 2.2 Numerical Solution . ....................... 42 2.2.1 Finite Difference Method . ................ 42 2.2.2 Newton’s Method Solution . ................ 44 2.2.3 Boundary Condition Implementation . ............ 46 2.2.4 Stresses, Pressures and Settlement . ................ 47 viii 2.2.5 Stability, Consistency and Convergence . ............ 48 2.3 Summary . .............................. 49 3. Sediment Consolidation - Model Applications . ................ 51 3.1 Uniform, Single Layer Consolidation . ................ 53 3.1.1 Townsend - Scenario A . ................ 53 3.1.2 Cargill - Craney Island Dredged Fill Material . ..... 57 3.1.3 Been and Sills - Combwich on Somerset Clay . ..... 60 3.2 Time-varying Sediment Loading . ................ 63 3.2.1 Multi-Deposited Sediment Loading ................ 64 3.2.2 Multi-Eroded Sediment (Un-)Loading . ............ 66 3.2.3 Sequential Loading and Unloading of Sediment Layers ..... 68 3.3 Summary . .............................. 73 4. Three-Dimensional Sediment Transport . ................ 75 4.1 Coupling Water Column Transport and Mobile Bed ............ 78 4.1.1 Hydrodynamics . ....................... 79 4.1.2 Bed Mass Conservation . ................ 80 4.1.3 Suspended Sediment Transport . ................ 84 4.2 Boundary Conditions . ....................... 85 4.3 Numerical Solution . ....................... 86 4.3.1 Additional Considerations . ................ 88 4.4 Outline of Modifications to the Model . ................ 88 4.4.1 Coupling Water Column, Bed Load and Bed Evolution . ..... 91 4.5 Summary . .............................. 96 5. Source/Sink Terms, Auxiliary Relations and Other Parameterizations
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