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The effects of flocculation on the entrainment of fluid mud layer
Estuarine, Coastal and Shelf Science ( IF 2.8 ) Pub Date : 2020-04-27 , DOI: 10.1016/j.ecss.2020.106784
Chunyang Xu , Yongping Chen , Yi Pan , Lili Yu

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.



中文翻译:

絮凝对夹带液泥层的影响

絮凝是粘性沉积物输送过程不可或缺的一部分,因为它将进一步影响其他过程,例如沉降,沉积以及侵蚀过程。为了了解絮凝对不同盐度流体泥浆夹带过程的影响,进行了一系列夹带和沉降实验。在环形水槽顶部的剪切环驱动下,在恒定的流体动力学条件下进行夹带实验。而沉降实验是在具有不同直径的圆柱体内进行的。结果表明,不同盐度的泥浆样品在垂直方向上可形成不同的泥沙浓度分布,这将显着影响泥浆的夹带率。结果还表明,在上层泥浆中,盐度较高的泥浆(E18)的夹带率比盐度较低的泥浆(E4)的夹带率小。泥沙试验表明,盐度较高的流体泥浆样品的沉降速率提高,在较低的泥沙浓度下达到胶凝浓度。这两种机理导致了在不同絮凝状态下流体泥浆中泥沙浓度的不同分布。因此,泥浆的特性,例如密度,粘度,屈服强度,浮力效应以及最终的夹带率随不同的流体泥浆样品而变化(初始沉积物浓度相同)。还努力用现有方程式预测夹带率。

更新日期:2020-04-27
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