SETTLING VELOCITY OF NATURAL PARTICLES
SETTLING VELOCITY OF NATURAL PARTICLES
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DOI：
10.1029/wr018i006p01615
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发表时间：
1982-01-01
影响因子：
5.4
通讯作者：
DIETRICH, WE
中科院分区：
文献类型：
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作者：
DIETRICH, WE
利用以前14项实验研究的数据，建立了一个经验公式，该公式解释了大小、密度、形状和圆度对天然泥沙沉降速度的影响。这一分析是根据四个无量纲参数进行的，即无量纲公称直径D*、无量纲沉降速度W*、Corey形状因子和幂圆度指数。对于高D*(大颗粒或致密颗粒)，圆度和形状因子的变化对沉降速度的影响程度相似。然而，对于自然产生的颗粒来说，圆度的变化要小得多，因此与形状相比，圆度是一个次要的控制因素。对于幂圆度为3.5，Corey形状因子为0.7的典型粗砂，其沉降速度约为球形的0.68，形状和圆度的影响对沉降速度的影响大致相同。在低D*时，形状或圆度对沉降速度的影响要小得多。此外，在低D*时，低圆度导致的沉降速度在低形状因子值时比在高形状因子值时更大。这似乎是由于较平的颗粒上的表面阻力增加所致。
Data from 14 previous experimental studies were used to develop an empirical equation that accounts for the effects of size, density, shape, and roundness on the settling velocity of natural sediment. This analysis was done in terms of four nondimensional parameters, namely, the dimensionless nominal diameterD*, the dimensionless settling velocityW*, the Corey shape factor, and the Powers roundness index. For highD*(large or dense particles), changes in roundness and shape factor have similar magnitude effects on settling velocity. Roundness varies much less for naturally occuring grains, however, and hence is a less important control than shape. For a typical coarse sand with a Powers roundness of 3.5 and a Corey shape factor of 0.7, the settling velocity is about 0.68 that of a sphere of the sameD*, with shape and roundness effects contributing about equally to the settling velocity reduction. At lowD*the reduction in settling velocity due to either shape or roundness is much less. Moreover, at lowD*, low roundness causes a greater decrease in settling velocity at low shape factor values than at high shape factor values. This appears to be due to the increased surface drag on the flatter grains.