Nuclear magnetic resonance imaging investigation of sedimentation of concentrated suspensions in non-Newtonian fluids
Nuclear magnetic resonance imaging investigation of sedimentation of concentrated suspensions in non-Newtonian fluids
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DOI：
10.1122/1.550895
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发表时间：
1998-12
影响因子：
3.3
通讯作者：
S. Bobroff;R. Phillips
中科院分区：
文献类型：
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作者：
S. Bobroff;R. Phillips
核磁共振成像用于研究几种非牛顿流体的沉降速率。研究表明，流体中的剪切稀化或弹性都会导致随时间变化的沉降速率，这是通过悬浮液-上清液界面的运动来测量的。沉降在过程开始时最快，随着时间的推移，沉降速度逐渐减慢。悬浮液垂直截面的二维图像清楚地显示了粘弹性流体沉降过程中非均匀微观结构的发展。细长的颗粒柱在重力方向上形成，这些颗粒柱被大小相当的纯流体区域分隔开。这种结构在牛顿流体的沉降中不存在，其中悬浮液微观结构在整个过程中是均匀的。
Nuclear magnetic resonance imaging is used to study rates of sedimentation in several non-Newtonian fluids. It is shown that either shear thinning or elasticity in a fluid can result in a time-dependent sedimentation rate, as measured by the motion of the suspension–supernatant interface. Sedimentation is most rapid at the beginning of the process, and grows steadily slower in time. Two-dimensional images of vertical sections of suspension show clearly the development of a nonhomogeneous microstructure during sedimentation in a viscoelastic fluid. Elongated columns of particles form in the direction of gravity, and these columns are separated by comparably sized regions of pure fluid. Such structures are not present in sedimentation in Newtonian fluids, where the suspension microstructure is homogeneous for the duration of the process.