利用離散元素法模擬及分析粒徑大小導致的顆粒流動分離行為

Abstract

本研究針對顆粒流中的尺寸分離現象進行深入探討，特別是分析大顆粒在眾多小顆粒中的運動行為及受力情形。透過離散元素法建立數值模型，本研究模擬並統計了大顆粒在無流體環境下的顆粒流中的受力狀況，以了解其運動機制。數值模擬提供了詳細的數據，使我們能夠精確觀察大顆粒在垂直方向上的位置變化及其所受的各種力的大小和方向。基於這些數據，本研究將大顆粒的運動分為兩類：上升區間與非上升區間，並進一步分析這兩類運動模式之間的差異。 通過比較大顆粒在上升區間和非上升區間的受力情形，我們試圖找出影響大顆粒上升的關鍵機制。研究結果顯示，大顆粒在上升過程中受到的碰撞力和重力的相互作用，對其運動行為有顯著影響。為了驗證這些發現，本研究進一步調整了顆粒的物理參數，觀察這些參數的變化如何影響碰撞力及顆粒的運動行為。除此之外，利用數值模擬的方法，詳細分析了大顆粒在顆粒流中的受力分佈。結果顯示，大顆粒在上升區間內的運動行為顯著不同於非上升區間，這主要歸因於兩區間內顆粒所受力的不同組合和大小。利用碰撞力區分接觸顆粒所扮演的角色，並且在更細分接觸顆粒與大顆粒的相對位置，利用碰撞顆粒位於大顆粒的第幾象限去做分析，如此一來便能清楚地知道接觸顆粒在不同接觸象限所扮演的角色是什麼，以及對大顆粒的碰撞力所扮演的角色。 本研究的結果不僅揭示了大顆粒在顆粒流中上升的機制，還提供了調整顆粒物理參數以控制其運動行為的方法。這些發現對於工程應用和自然現象的預測具有重要意義。例如，在礦物處理、土壤改良和自然災害防治等領域，理解和控制顆粒的運動行為可以提高處理效率和安全性。

This study investigates size segregation in granular flows, focusing on the behavior and force conditions of large particles among smaller particles. Using the Discrete Element Method (DEM), we established a numerical model to simulate and analyze the forces experienced by large particles in a fluid-free granular flow environment. Numerical simulations provide detailed data, allowing precise observation of the vertical positional changes and the forces acting on large particles. Based on these data, we categorized the motion of large particles into ascending and non-ascending intervals and analyzed the differences between these motion patterns. Comparing the force conditions in these intervals, we identified key mechanisms influencing the ascent of large particles. Results indicate that the interaction between collision forces and gravity significantly impacts their motion. To validate these findings, we adjusted particle physical parameters and observed how these changes affect collision forces and particle motion behavior. Additionally, the study analyzed the force distribution on large particles, showing significant differences in motion behavior between ascending and non-ascending intervals. By distinguishing the roles of contact particles through collision forces and quadrant positions, we clarified the impact of contact particles. The findings reveal the mechanisms behind the ascent of large particles and offer methods for adjusting physical parameters to control their motion. These insights are crucial for applications in mineral processing, soil improvement, and natural disaster prevention, enhancing processing efficiency and safety.