Substrate impact on flow induced particle motion in laminar shear flow

层流剪切流中基质对流动引起的颗粒运动的影响

• 批准号: 269455552
• 负责人: Professor Dr. Andreas Wierschem
• 金额: --
• 依托单位: Lehrstuhl für Strömungsmechanik (LSTM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/269455552?language=en
• 关键词: Substrate; impact; flow; induced; particle

Flow induced detachment and motion of solid particles on a fixed substrate or granular bed is of fundamental relevance in numerous natural and industrial systems. As examples sediment and granular transport in filtration, natural watercourses and piping systems, particle transport in the respiratory system, and the cleaning of surfaces may be mentioned. In microfluidics, spherical particles are progressively used as information carrier or for actuators like valves or pumps. Therefore, an important precondition is the controlled positioning of particles. While the motion of single particles on smooth walls is quite well understood, this does not hold for structured surfaces and granular beds. Despite numerous studies concerning the onset of particle motion, the motion itself or rather the material transport, these technologically important processes are still not well described. This is due to the fact that particle removal has been studied exclusively for disordered sediment layers and has been tried to describe using not well-defined parameters in the existing models. Since the precise particle arrangement is ignored, the effects of substrate geometry, exposure to the flow and shading by neighboring particles remains unclear. Hence, the impact of substrate geometry and of neighboring particles on the onset of particle motion and the motion along the substrate itself remains unclear.Granular beds hinder particle motion in two ways: On the one hand, the uneven substrate poses an obstacle, which downstream contact angle has to be overcome, on the other hand, its shades the particle against the flow. In an analogue manner, neighboring particles serve as an additional hindrance. Starting from this observation, we plan to vary the relevant parameters. The aim of the project is to describe the onset of particle motion and the motion along the substrate itself in laminar shear flows quantitatively in a model without recourse to not well-defined parameters.

在许多自然和工业系统中，固体颗粒在固定基质或颗粒床上的流动诱导分离和运动具有基本的相关性。例如，过滤、天然水道和管道系统中的沉积物和颗粒输送，呼吸系统中的颗粒输送以及表面清洁。在微流体中，球形颗粒逐渐被用作信息载体或用于阀门或泵等致动器。因此，一个重要的先决条件是粒子的受控定位。虽然单个颗粒在光滑壁面上的运动已经很好地理解了，但对于结构化表面和颗粒床，这并不成立。尽管有许多关于粒子运动开始的研究，运动本身或更确切地说是物质传输，这些技术上重要的过程仍然没有得到很好的描述。这是由于这样一个事实，即颗粒去除已专门研究无序沉积层，并已试图描述使用现有模型中没有明确定义的参数。由于忽略了精确的颗粒排列，基底几何形状、暴露于流动和相邻颗粒的遮蔽的影响仍然不清楚。因此，基质几何形状和相邻颗粒对颗粒运动开始和沿着基质本身运动的影响仍然不清楚。颗粒床以两种方式阻碍颗粒运动：一方面，不均匀的基质构成障碍，必须克服下游接触角，另一方面，它遮挡颗粒的流动。以类似的方式，相邻的粒子充当额外的阻碍。从这一观察出发，我们计划改变相关参数。该项目的目的是在一个模型中定量地描述颗粒运动的开始和沿着基底本身的运动，而不依赖于没有明确定义的参数。

项目成果

Shear-induced incipient motion of a single sphere on uniform substrates at low particle Reynolds numbers

• DOI: 10.1017/jfm.2017.370
• 发表时间: 2017-07
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: J. R. Agudo;C. Illigmann;G. Luzi;A. Laukart;Antonio Delgado;Andreas Wierschem

Effect of particle size ratio on shear-induced onset of particle motion at low particle Reynolds numbers: From high shielding to roughness

• DOI: 10.1063/1.5108800
• 发表时间: 2019-06
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: N. Topic;S. Retzepoglu;M. Wensing;C. Illigmann;G. Luzi;J. R. Agudo;A. Wierschem