在功率定律流体中研究squirmer的沉积特征
Amin Ullah1, Jianzhong Lin2,3, Yuxiang Yin1
1State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou, 310027, China.
The European physical journal. E, Soft matter
|October 14, 2024
概括
这项研究从数值上研究了squirmer特征如何影响它们在功率定律流体中的沉积. 拖拉机类型和流体特性显著影响沉积模式和速度,在某些流体中,拉拉机的沉积速度比推拉机快.
科学领域:
- 流体动力学 流体动力学
- 非牛顿流体力学 不牛顿流体力学
- 计算物理 计算物理
背景情况:
- 了解复杂液体中的微游泳器行为对于各种应用至关重要.
- 斯奎默模型被用来研究在流体环境中的自行粒子.
- 动力定律流体表现出非线性粘度,影响粒子动态.
研究的目的:
- 为了数值分析一个squirmer的沉积特征在一个垂直通道充满了动力法流体.
- 为了研究流浪者游泳类型,自动推进力,流体体质 (动力定律指数) 和密度比对沉积的影响.
- 识别和描述不同的沉积模式.
主要方法:
- 二维格子博尔茨曼法 (LBM) 用于数值模拟.
- 模拟涵盖了一系列参数:游泳类型 (β:-5至5),自行推进强度 (α:0.5至1.1),功率定律指数 (n:0.5至1.5),密度比 (γ:1.01,1.5,2.3).
- 分析的重点是确定不同的结算模式及其对各种参数的依赖性.
主要成果:
- 观察到四种不同的沉积模式:稳定的中心下降,墙壁下降,大幅度振荡和中心线振荡.
- 与剪切加厚 (n>1) 流体相比,Squirmer动态显示了剪切稀释 (n<1) 和牛顿 (n=1) 流体的波动增加.
- 拉拉器 (β>0) 在剪切稀释和牛顿流体中表现出比推拉器 (β<0) 更快的沉积,拉拉器表现出小振荡,推拉器表现出大振荡.
结论:
- 在动力定律流体中的沉积对其游泳行为和流体的质性质非常敏感.
- 拉杆式杆在较少粘性液体中表现出更高的沉积效率,而推杆式杆则表现出更复杂的振荡运动.
- 更高的密度比率 (γ) 会导致更明显的波动,这表明在更大的密度不匹配时,不稳定性会增加.
相关概念视频
01:20Stokes' Law
1.2K
Viscous forces, like friction, are intermolecular forces that resist the relative motion of molecules over each other. When a solid body moves through a liquid, viscous forces drag it in the opposite direction. The force's magnitude depends on the solid's shape and size, as well as its speed and the liquid's coefficient of viscosity, density and temperature.
The expression for the force on a solid spherical object in a fluid is called Stokes' law. Stokes' law is valid only...
The expression for the force on a solid spherical object in a fluid is called Stokes' law. Stokes' law is valid only...
1.2K
01:30Typical Model Studies
342
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.
342
01:17Accelerating Fluids
1.0K
When a fluid is in constant acceleration, the pressure and buoyant force equations are modified. Suppose a beaker is placed in an elevator accelerating upward with a constant acceleration, a. In the beaker, assume there is a thin cylinder of height h with an infinitesimal cross-sectional area, ΔS.
The motion of the liquid within this infinitesimal cylinder is considered to obtain the pressure difference. Three vertical forces act on this liquid:
The motion of the liquid within this infinitesimal cylinder is considered to obtain the pressure difference. Three vertical forces act on this liquid:
1.0K
01:18Newtonian Fluid: Problem Solving
199
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...
199
01:20Characteristics of Fluids
3.8K
When a force is applied parallel to the top surface of a solid, it resists the applied force due to the internal frictional forces between the layers of the solid known as shearing resistance. However, when the force is removed, the shearing forces restore the original shape of the solid. Other deformation forces also cause temporary changes in shape if the forces are not beyond a threshold magnitude. Solids tend to retain their shape, making the study of their rest and motion easier. Beyond...
3.8K
01:27Energy Considerations in Open Channel Flow
81
Open channel flow, where a fluid flows with a free surface exposed to the atmosphere, is primarily governed by gravitational and surface effects, distinguishing it from closed conduit or pipe flow. In open channels such as rivers, canals, and artificial channels, energy analysis provides valuable insights into flow behavior and the relationship between depth, velocity, and slope.Specific Energy and Flow DepthIn open channel flow, the specific energy, E, combines the gravitational potential...
81