Direct measurements of shear-induced particle migration in suspensions of bimodal spheres
Direct measurements of shear-induced particle migration in suspensions of bimodal spheres
复制标题
双峰球体悬浮液中剪切引起的颗粒迁移的直接测量
DOI：
10.1007/bf00437303
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发表时间：
1994
期刊：
影响因子：
2.3
通讯作者：
A. Graham
中科院分区：
文献类型：
--
作者：
D. Husband;L. Mondy;E. Ganani;A. Graham
文献中报道的各种研究已经确定，最初混合良好的悬浮液受到非均匀剪切流的影响，可以获得各向异性的颗粒结构。还表明，非均匀剪切导致单峰球悬浮液的分解，即固体浓度的梯度形成。本研究的目的是确定非均匀剪切流对双峰颗粒悬浮液的影响，特别是确定固体浓度梯度是否伴随着粗颗粒相对于细颗粒的尺寸偏析。我们采用了最简单、最直接的方法来测定固体相对浓度：透明悬浮液中示踪颗粒的目测和粗、细固体组分的物理分离。研究了三种不同类型的非均匀剪切流动，每种情况下的数据都支持两个主要结论：1)悬浮颗粒从高剪切速率区域迁移到低剪切速率区域；2)粗颗粒比细颗粒迁移得快得多，导致最初混合良好的悬浮颗粒的尺寸偏析。虽然前一结论与文献中报道的其他研究一致，但据我们所知，本文提供了第一个支持后一结论的数据，并在有限程度上量化了后一结论。
A variety of studies reported in the literature have established that initially well mixed suspensions subjected to non-homogeneous shear flows attain an anisotropic particulate structure. It has also been shown that non-homogeneous shearing causes suspensions of unimodal spheres to demix, i.e., gradients in solids concentration are formed. The objective of this study was to determine the effect of non-homogeneous shear flows on suspensions of bimodal particles, and specifically, to determine if the solids concentration gradients which develop are accompanied by size segregation of the coarse with respect to the fine fraction. We used the simplest and most direct methods to determine the relative solids concentrations: visual observation of tracer particles in transparent suspensions and physical separation of the coarse and fine solid fractions. Three different types of non-homogeneous shear flows were examined, and in each case the data support two main conclusions: 1) suspended particles migrate from regions of high shear rate to regions of low shear rate, and 2) the coarse fraction of particles migrates much faster than the fine fraction, leading to size segregation of initially well-mixed suspensions. While the former conclusion is consistent with other studies reported in the literature, to our knowledge this paper provides the first data supporting and, to a limited extent, quantifying the latter conclusion.