Turbulence modulation in non-uniform open-channel clay suspension flows
Turbulence modulation in non-uniform open-channel clay suspension flows
复制标题
非均匀明渠粘土悬浮流中的湍流调制
DOI：
10.1002/essoar.10511877.1
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
De Vet M
中科院分区：
文献类型：
--
作者：
De Vet M
粘土的粘聚性促进粘土絮体和凝胶的形成，相对较小的悬浮粘土浓度可以增强或抑制流动中的湍流。水流自然是非均匀的，在空间和时间上都是变化的，然而非均匀明渠粘土悬浮流的动力学却鲜为人知。为了研究非均匀流条件下粘性粘土悬浮体对水流动力学变化的影响，采用减速和加速粘性粘土悬浮体明渠回流明渠水流进行了新的试验。流动在粘土流动类型之间转换，随着流动适应流速的变化，具有不同程度的湍流增强和衰减。实验结果表明，减速粘土悬浮流比加速粘土悬浮流具有更长的适应时间。粘性沉积物颗粒之间粘性粘结的形成是一个与时间相关的过程，而建立粘性粘性粘结需要更多的时间，如在减速流动中，比在加速流动中打破粘性粘结需要更多的时间。这种滞后性对于浓度较高的减速流来说更为明显，因为减速流流经的湍流增强和衰减的流相种类较多。这些不同的适应时间尺度和相关的粘土流动类型转变可能会影响各种河流和海底环境中的侵蚀和沉积过程。
Cohesive properties of clay promote the formation of clay flocs and gels and relatively small suspended clay concentrations can enhance or suppress turbulence in a flow. Flows are naturally non-uniform, varying in space and time, yet the dynamics of non-uniform open-channel clay suspension flows are poorly understood. To research the influence of suspended cohesive clay on changing flow dynamics under non-uniform flow conditions, new experiments were conducted using decelerating and accelerating clay suspension open-channel flows in a recirculating flume. The flows transition between clay flow types, with different degrees of turbulence enhancement and attenuation as the flow adapts to the change in velocity. The experimental results show that decelerating clay suspension flows have a longer adaptation time than accelerating clay suspension flows. The formation of bonds between cohesive sediment particles is a time-dependent process and establishing clay bonds, as in the decelerating flows, requires more time than breaking them, as in the accelerating flows. This hysteresis is more pronounced for higher concentration decelerating flows that pass through a larger variety of flow phases of turbulence enhancement and attenuation. These different adaptation time scales and associated clay flow type transitions are likely to affect erosional and depositional processes in a variety of fluvial and submarine settings.