Stresses in Dilute Solutions of Bead‐Nonlinear‐Spring Macromolecules. III. Friction Coefficient Varying with Dumbbell Extension
Stresses in Dilute Solutions of Bead‐Nonlinear‐Spring Macromolecules. III. Friction Coefficient Varying with Dumbbell Extension
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珠非线性弹簧大分子稀溶液中的应力随哑铃伸展的变化。
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发表时间：
1975
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通讯作者：
R. Tanner
中科院分区：
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作者：
R. Tanner
哑铃悬浮液的力学检查扩展到包括摩擦系数的增加与分子的扩展，无论是在弱流和强流。最有趣的结果发生在稳定的拉伸流动中，其中发现“滞后”回线，使得在一定范围的拉伸速率中，两种拉伸粘度是可能的，其中一种取决于拉伸速率的先前历史。这个结果很有趣，因为它增加了湍流减阻的解释的合理性，这些解释取决于将分子保持在扩展的、高度耗散的配置中。磁滞回线也是感兴趣的，因为它代表了一个有效的无限记忆的选择性类型，这是不兼容的通常假设褪色的记忆通常与简单的流体概念的连续介质力学，虽然我们的稀溶液模型显然是一个简单的流体。在稳态剪切过程中没有发现磁滞回线。
The examination of the mechanics of dumbbell suspensions is extended to include the increase of the friction coefficient with molecular extension, both in weak flows and in strong flows. The most interesting result occurs in steady elongational flows where a “hysteresis” loop is found, so that in a certain range of elongation rates two elongational viscosities are possible, the one occurring depending on the previous history of the elongation rate. This result is of interest because it increases the plausibility of those explanations of turbulent drag reduction which depend on maintaining the molecules in an extended, highly dissipative configuration. The hysteresis loop is also of interest in that it represents an effectively infinite memory of a selective type which is not compatible with the usual hypotheses about fading memory usually associated with the simple fluid concepts of continuum mechanics, although our dilute solution model is clearly a simple fluid. No hysteresis loop was found in steady sh...