在密集悬浮中直接观察动态剪切阻塞
Ivo R Peters1, Sayantan Majumdar1, Heinrich M Jaeger1
1James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
Nature
|April 5, 2016
概括
密集的悬浮体会出现剪切阻塞,这种现象是剪切应力,而不是剪切速率,控制液态和固态之间的过渡. 这项研究将稳定状态和短暂的行为统一在一个动态的剪切干扰框架下.
科学领域:
- 物理
- 材料科学
- 病理学
背景情况:
- 硬颗粒的密悬浮表现出非牛顿式的行为,如剪切加厚和冲击诱导的固化.
- 这些现象通常与阻塞过渡有关,但现有的模型难以将稳定状态流与过渡固化和密度变化相协调.
研究的目的:
- 系统地探索密集悬浮的稳定状态和过渡状态,以连接剪切加厚和堵塞.
- 建立一个统一的框架,解释粒子密度,剪切应力和密集悬浮中的阻塞过渡之间的关系.
主要方法:
- 在稳定状态和过渡状态中对密度悬浮进行实验研究.
- 直接追踪短暂的剪切阻塞前线.
- 粒子密度的系统变化和施加的剪切应力.
主要成果:
- 通过短暂的剪切阻塞面,可以通过纯粹的剪切,而不是压缩来实现完全堵塞的固体状况.
- 确定剪切应力作为关键控制参数,而不是剪切速率.
- 用粒子密度和剪切应力绘制状态图,确定不连续的剪切加厚为边缘堵塞状态.
结论:
- 开发了基于动态剪切干扰的密集悬挂行为的统一框架.
- 通过剪切阻塞过程连接稳定状态剪切加厚和暂时凝固.
- 拟议的框架与现有的实验和模拟数据一致.
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