內部結構對通過窄管粒子之動態過程的影響

Abstract

粒子透過形變穿透進入狹窄通道的行為，是特定領域中非常重要的研究課題，然而其動態研究卻非常稀少。本研究採用結構單純的玩具模型進行模擬及分析，試著找出內部結構如何影響粒子穿透的行為。在此論文中，我們尤其關注內部結構對粒子形變與穿透所需時間的影響。 我們使用二維晶格波茲曼法來建模流體、單層彈簧模型模擬粒子形變。我們考慮具單棒狀內部結構的粒子。我們的模擬結果顯示，粒子的穿透過程涉及粒子變形和內部結構的重新定向過程。此重新定向過程的旋轉速度，決定穿透時間受粒子傾斜角度影響的程度。此外，內部結構的物理性質，例如彈性硬度、彎曲硬度、或兩者之間的比值都會影響具單棒狀內部結構粒子的穿透時間和穿透模式。 我們通過追蹤粒子在穿透過程中不同區域的位能變化，提出傾斜角度影響穿透時間的物理解釋。並且我們的結果與一些先前的實驗在質性上吻合，證明了我們系統的可靠性。

The deformation and transition behaviors of particles are very important research topics that give a few specific fields. However, there are few studies about them. This thesis used a simple model to simulate and analyze such processes and try to find out how the inner structure affects the transit physics of soft particles. I investigated the effect of particle inner structure on particle deformation and the time required to enter and pass through a constrictive tube which diameter smaller than the particle diameter. We used the 2D lattice Boltzmann method to model the fluid flow, and a single-layered spring model for particle deformation. We considered particles with inner beams. Our results show that the transit time for a particle with an inner beam strongly depends on the beam tilt angle as the particle enters the tube. Furthermore, the transit process involves particle deformation and reorientation of the beam to align with the constriction geometry. The properties of the inner structure, such as the elastic constant, the bending constant, and the ratio of them, will affect the transit time and the transit process. We analyzed the transit energy by tracing the change in potential energy of different parts of a particle to find the physical explanations of the relationship between the transit time and the tilt angle. Our results capture the qualitative physics with previous experiments.