Direct Determination of Apparent Slip for a Ducted Flow of Polyacrylamide Solutions
Direct Determination of Apparent Slip for a Ducted Flow of Polyacrylamide Solutions
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直接测定聚丙烯酰胺溶液管道流的表观滑移
DOI：
10.1122/1.549952
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发表时间：
1987
影响因子：
3.3
通讯作者：
W. Schauerte
中科院分区：
文献类型：
--
作者：
H. Müller;H. Löbl;W. Schauerte
在距离管壁0.15 μm处测量了阴离子聚丙烯酰胺（Praestol，来自Stockhausen公司，浓度c0=0.25重量百分比）水溶液的流速分布。可以根据流动曲线重新计算所测得的剖面。将剖面外推至管壁，得到有限的速度值（滑移速度vs）。这种滑移现象不能仅根据流动曲线提前计算出来。在所检测的壁面剪切应力τw范围内，对于给定的聚合物浓度，vx与τw的关系是线性的，没有阈值。在溶液中加入毛细管活性物质或强电解质，滑移速度减小；二价阳离子（ca++）比一价阳离子（Na+）有效十倍。随着离壁面距离的增加，流速从v=0增加到v=vs发生在与壁面接壤的流体层内（或吸附的宏观颗粒层内）。
Velocity profiles were measured up to a minimum distance of 0.15 μm from the wall for tube flow of aqueous solutions of anionic Polyacrylamides (Praestol from the Stockhausen Corporation, at a concentration c0=0.25 percentage by weight). The profiles measured could be recalculated on the basis of the flow curve. Extrapolation of the profile to the wall resulted in finite velocity values (slip‐velocity vs). This slip phenomenon could not be calculated in advance on the basis of the flow curve alone. Within the range of wall shear stress τw examined, the dependence of vx on τw was linear for a given polymer concentration and exhibited no threshold. The slip velocity vs decreased if capillary active substances or strong electrolytes were added to the solution; divalent cations (Ca+ +) being ten times more effective than mono‐valent ones (Na+). The increment of flow velocity from v=0 to v=vs with increasing distance from the wall occurs within a fluid layer which borders the wall (or a layer of adsorbed macro...