A computational investigation of the interstitial flow induced by a variably thick blanket of very fine sand covering a coarse sand bed
A computational investigation of the interstitial flow induced by a variably thick blanket of very fine sand covering a coarse sand bed
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对覆盖粗砂床的不同厚度的极细砂层引起的间隙流的计算研究
DOI：
10.1007/s00367-017-0502-x
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发表时间：
2017
影响因子：
2.1
通讯作者：
Bartzke
中科院分区：
文献类型：
--
作者：
Bartzke
相对于由均匀粒度分布组成的床，覆盖沉积物床可具有不同的床移动性特征。大多数影响床移动性的过程都是在床的附近甚至床本身内进行的。为了模拟模拟实验的一般条件，采用耦合有限差分法水流模型和离散单元法颗粒模型，建立了高分辨率的三维"水槽“数值模型。该方法被应用于调查的物理过程中覆盖的沉积物床的影响下，变化的流速。四组模拟，其中均匀大颗粒（600 μm）的基质被不同厚度的小颗粒层（80 μm）覆盖;覆盖层厚度约为80、350、500和700 μm）。所有床都经受五种预定流速（U1-5=10-30 cm/s）。流体剖面，相对颗粒距离和孔隙度的变化，床内的每种配置进行了测定。数据显示，随着覆盖层厚度的增加，越来越多的小颗粒积聚在最靠近表面的较大颗粒之间的压痕中。这导致孔隙率降低和进入床的流量减少。此外，随着覆盖层厚度的增加，越来越多的较小颗粒被迫进入较大颗粒之间的孔隙空间，导致孔隙率进一步降低。这最终导致间隙流（其通常允许床的较深部分中的颗粒夹带）减少到使床稳定的程度。
Blanketed sediment beds can have different bed mobility characteristics relative to those of beds composed of uniform grain-size distribution. Most of the processes that affect bed mobility act in the direct vicinity of the bed or even within the bed itself. To simulate the general conditions of analogue experiments, a high-resolution three-dimensional numerical ‘flume tank’ model was developed using a coupled finite difference method flow model and a discrete element method particle model. The method was applied to investigate the physical processes within blanketed sediment beds under the influence of varying flow velocities. Four suites of simulations, in which a matrix of uniform large grains (600 μm) was blanketed by variably thick layers of small particles (80 μm; blanket layer thickness approx. 80, 350, 500 and 700 μm), were carried out. All beds were subjected to five predefined flow velocities (U1–5=10–30 cm/s). The fluid profiles, relative particle distances and porosity changes within the bed were determined for each configuration. The data show that, as the thickness of the blanket layer increases, increasingly more small particles accumulate in the indentations between the larger particles closest to the surface. This results in decreased porosity and reduced flow into the bed. In addition, with increasing blanket layer thickness, an increasingly larger number of smaller particles are forced into the pore spaces between the larger particles, causing further reduction in porosity. This ultimately causes the interstitial flow, which would normally allow entrainment of particles in the deeper parts of the bed, to decrease to such an extent that the bed is stabilized.
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影响因子：
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