在流量停止后,粘弹性流体的异质性诱导的收缩
Patrick J McCauley1, Satish Kumar1, Michelle A Calabrese1
1Department of Chemical Engineering and Materials Science, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, USA. kumar030@umn.edu.
Soft matter
|May 29, 2024
概括
复杂流体的流量逆转发生在弹性和流量异质性同时发展时. 一种新的方法通过测量切断停止后的流体收缩来量化流动异质性,支持这个假设.
科学领域:
- 风病学和软物质物理学.
- 复杂的流体动力学.
- 粘弹性和非牛顿流体行为.
背景情况:
- 复杂的流体,如虫状菌体 (WLMs),在剪切启动过程中可以表现出异质的流量和流量逆转.
- 流量逆转假设发生在流体具有显著的弹性并且在压力过度后发展异质流量时.
- 现有的方法缺乏在剪切启动过程中对流量异质性的定量评估.
研究的目的:
- 开发和验证一种用于测量复杂流体流动异质性的新方法.
- 通过实验验证将流量逆转与弹性和即时流量异质性联系在一起的假设.
- 提供对粘弹性系统中空间异质流量的定量见解.
主要方法:
- 开发了一种新的技术来测量流量异质性,通过使用粒子跟踪速度计在流量停止时量化流体收缩.
- 在凝类和流体类WLM启动期间在关键时间点停止剪流.
- 在收缩过程中分析速度概况,以推断流动异质性的程度.
- 理论上分析异质库埃特流,使用上方对流的麦克斯韦和杰曼-库克-贝里斯模型.
主要成果:
- 新方法通过流体收缩测量成功量化了流动异质性.
- 观察到,在凝状的WLM中,流量异质性在流量逆转之前更早地发展.
- 实验结果支持这样一个假设:显著的弹性和即时的流量异质性驱动流量逆转.
- 理论模型证实,质性质的差异可以诱导显著的流体收缩.
结论:
- 开发的粒子跟踪速度测量方法提供了关于复杂流体流动异质性的定量数据.
- 实验结果验证了在粘弹性流体中逆流的拟议标准.
- 这种技术适用于研究各种复杂流体中的异质流量,无论流量逆转是否发生.
相关概念视频
01:21Plastic Behavior
196
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and...
196
01:17Viscosity
5.8K
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
5.8K
01:18Residual Stresses in Bending
160
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
160
01:18Newtonian Fluid: Problem Solving
218
Newtonian fluids exhibit a constant viscosity, meaning their shear stress and shear strain rate are directly proportional. This property ensures a predictable and stable response to applied forces, maintaining a linear relationship between force and flow. Examples include water, air, and light oils, consistently demonstrating this proportional behavior regardless of external conditions.
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
218
01:27Types of Fluids
235
Fluids can be classified into Newtonian and non-Newtonian fluids based on their response to shear stress. Newtonian fluids have a linear relationship between shear stress and the shear strain rate, following Newton's law of viscosity. Their viscosity remains constant regardless of the shear rate, making their behavior predictable and easier to analyze. Common examples include water, air, oil, and gasoline.
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and...
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and...
235
02:57Surface Tension, Capillary Action, and Viscosity
27.7K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
27.7K