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Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

The evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. This thesis aims to better understand fine sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL). Les mer
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Vår pris: 1181,-

(Paperback) Fri frakt!
Leveringstid: Sendes innen 21 dager
På grunn av Brexit-tilpasninger og tiltak for å begrense covid-19 kan det dessverre oppstå forsinket levering.

Om boka

The evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. This thesis aims to better understand fine sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL). Field observations, experimental data analysis, theoretical analysis and numerical models are employed. Silt-dominated sediments are sensitive to flow dynamics and the suspended sediment concentration (SSC) increase rapidly under strong flow dynamics. This research unveils several fundamental aspects of silty sediment, i.e., the criterion of the incipient motion, the SSC profiles and their phase-averaged parameterization in wave-dominated conditions. An expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. A process based intra-wave 1DV model for flow-sediment dynamics near the bed is developed in combined wave-current conditions. The high concentration layer (HCL) was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the SSC in the HCL. Finally, based on the 1DV model, the formulations of the mean SSC profile of silt-sand sediments in wave conditions were proposed. The developed approaches are expected to be applied in engineering practice and further simulation.

Fakta

Innholdsfortegnelse

1 Introduction
1.1. Background
1.2. Behaviour of sediments with different grain sizes
1.3. Wave-current bottom boundary layer (BBL)
1.4. Numerical simulation for sediment transport under combined waves and currents
1.5. Key problems in sediment transport modelling
1.6. Objectives and research questions
1.7. Thesis organization


2 Sediment transport in silt-dominated coastal areas: field works and data analysis
2.1. Introduction
2.2. Field works and data analysis in northwestern Caofeidian sea area of Bohai bay
2.3. Collected field data in some silt-dominated coasts
2.4. Summary


3 Incipient motion of silt-sand under combined action of waves and currents
3.1. Introduction
3.2. Analysis of sediment incipient motion under waves and currents
3.3. Derivation
3.4. Verification and discussion
3.5. Conclusion and remarks


4 High sediment concentration layer of fine sediments: modelling by a 1DV model
4.1. Introduction
4.2. A 1DV model for flow-sediment movement in wave-current BBL
4.3. Model verification
4.4. Sensitivity analysis and discussion: factors that impact the sediment concentration profile of the HCL
4.5. Conclusion


5 The mean SSC of silty sediments under wave-dominated conditions
5.1. Introduction
5.2. Methods and Materials
5.3. Mean sediment concentration profile under different bed forms
5.4. Depth-averaged sediment concentration under waves
5.5. Conclusion


6 Conclusions and recommendations
6.1. Conclusions
6.2. Recommendations


Appendix A. Derivation of Reynolds equation for wave-current motions
Appendix B. Time varying functions of the eddy viscosity and the reference concentration
Appendix C. The formula for reference concentration
Appendix D. Description of the 1DV model
Appendix E. The procedures of depth-averaged SSC in Matlab script

Om forfatteren

Liqin Zuo was born in 1980 in Shandong Province, China. He studied Hydrology and Water Resource for his bachelor degree in Hohai University between 1999 and 2003, and subsequently studied Harbor, Coastal and Near-shore Engineering in Nanjing Hydraulic Research Institute (NHRI) from 2003 - 2006 for his postgraduate degree. Liqin has been working in NHRI since 2006, where he was promoted as senior engineer in 2014. He participated a joint research project of NWO-NSFC between the Netherlands and China, for which he started his PhD study in IHE Delft and TU Delft in the Netherlands 2014 - 2018, working on the topic of sediment alluvial process in wave-current bottom boundary layer.