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Pan, Y.; Yin, S.; Chen, Y.; Yang, Y.; Xu, Z., and Xu, C., 2019. A practical method to scale the sedimentary parameters in a lightweight coastal mobile bed model. Journal of Coastal Research, 35(6), 1351–1357. Coconut Creek (Florida), ISSN 0749-0208. The coastal mobile bed model (CMBM) is an important approach to understand coastal sedimentary processes. The scaling of sedimentary parameters in a reduced-scale CMBM is one of the key procedures ensuring the reliability of the model, and the scaling relationships should be derived according to the similarity of dominant sedimentary process, with some less important similarity relationships relaxed. For a CMBM of which the processes of mobilization and fall of sediment are in transitional conditions, the scaling of sedimentary parameters is especially difficult because no mechanism dominates and the relationships between parameters are complicated. This paper proposes a local curve-fitting (LCF) method to avoid complicated relationships in deriving scaling relationships by fitting the complicated expressions with a simple relationship in the study range so that the scaling relationships can satisfy corresponding similarity criterion. The LCF method is introduced via the scaling of a reduced-scale profile model of the evolution of a submerged berm under the effects of small waves. The scaling relationships are derived according to the similarities of sediment mobilization, similarities of the fall of sediment, and Froude criterion. A mobile bed model was created based on the calculated of the LCF method, and the model results show the same evolution trend with field data, which proves the reasonability and validity of the LCF method. The LCF method provides a practical method to facilitate the deriving of scaling relationships of a CMBM of which the processes of mobilization and fall of sediment are in transitional conditions. It also provides a reference for other reduced-scale laboratory tests with complicated relationships between parameters but with limited study ranges. [ABSTRACT FROM AUTHOR]

ABSTRACT Xu, C.Y.; Chen, Y.P., and Yu, L.L., 2018. Numerical Studying on The Sedimentary Processes at A Mudflat Near Yangtze River. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1201–1205. Coconut Creek (Florida), ISSN 0749-0208. A two-phase model for studying the sedimentation processes is presented. The simple flocculation model is incorporated in the two-phase model to take account the flocculation effects on the settling velocity and thus the distribution of suspended sediment concentration. The model is applied to study the sedimentation processes at a mudflat and the suspended sediment concentration is presented and compared with measured data. The results show that it is important to include the flocculation effects in predicting the vertical profile of sediment concentration. [ABSTRACT FROM AUTHOR]

Flocculation is an integral part for cohesive sediment transport processes as it will further influence other processes such as settling, deposition as well as erosion processes. To understand the impacts of flocculation on entrainment process of fluid mud with different salinities, a series of entrainment and sedimentation experiments were conducted. Entrainment experiments were conducted under constant hydrodynamic conditions driven by a shear ring on the top of an annular flume. While the sedimentation experiments were conducted within cylinders with different diameters. Results show that fluid mud samples with different salinities can form different distributions of sediment concentration in the vertical direction, which will significantly influence the entrainment rate of fluid mud. Results also show that entrainment rate of fluid mud with higher salinity (E18) is smaller than that of fluid mud with lower salinity (E4) in the upper layer of fluid mud. Sedimentation tests show that the settling rate of fluid mud sample with higher salinity is enhanced and the gelling concentration is reached at a lower sediment concentration. These two mechanisms cause the different distributions of sediment concentration for fluid mud under different flocculation states. Accordingly, the mud characteristics such as density, viscosity, yield strength, buoyancy effects and eventually the entrainment rate vary with different fluid mud samples (the initial sediment concentrations are the same). An effort has also been made to predict the entrainment rate with existing equation. The good agreement between from equation and experimental results further demonstrates that the flocculation process should be considered when calculating the entrainment rate, as accurate prediction of the entrainment rate of fluid mud requires the details of sediment concentration and rheological properties of fluid mud in the vertical direction. • Entrainment and sedimentation tests were conducted in this study. • The flocculation effects will enhance the settling of fluid mud layer. • Fluid mud with higher salinity reaches gelling point at low concentration. • Flocculation effects make the sediment distributed uniformly in the mud layer. • Vertical structure has to be considered to get realistic entrainment rate. [ABSTRACT FROM AUTHOR]