謝尚賢臺灣大學：土木工程學研究所林立欣Lin, Li-ShinLi-ShinLin2007-11-252018-07-092007-11-252018-07-092005http://ntur.lib.ntu.edu.tw//handle/246246/50228有鑑於離散元素法的模擬隨元素數量增加伴隨而來的龐大計算時間，本研究提出了離散元素法的平行策略，而此平行策略係建立在一個能勝任多種元素形狀與多種元素間力學機制的離散元素模擬的離散元素程式架構，名為VEDO架構(VErsatile Discrete Objects framework)，其設計上將元素模型描述與力學機制演算法兩者抽離，僅在執行期間求解碰撞力學行為時將兩者作動態連結。本研究詳述了平行策略中的各項細節，包括工作量如何分配、處理器間溝通的時機與訊息內容等。 本研究建置出的平行離散元素模擬程式已應用在自充填混凝土砂漿的流動行為模擬。砂漿元素為由混凝土中細骨材、水、粉體共同構成的膠狀溶液，欲作自充填混凝土的流動模擬，可取其離散元素模型為粗骨材元素(代表粗骨材)與砂漿元素的二相組合。然而，砂漿元素為以離散顆粒模擬漿液的虛擬元素，顆粒參數與配比參數的關聯必須先經由砂漿流動試驗數據與砂漿流動模擬結果來建立。由於三維砂漿模擬需要很多的元素數目以致於計算量龐大，本研究建置出的平行離散元素程式藉由多個處理器的分工以減少執行時間，以使三維砂漿模擬能實現。In order to reduce the computation time involved with DEM (Discrete Element Method) simulation with large numer of elements, this research proposes a parallel strategy for a DEM simulation program framework, named VEDO (VErsatile Discrete Objects framework). In the design of VEDO framework, element model description and inter-element mechanism algorithm are separated, so VEDO framework is capable of performing simulations having elements with various shapes and various inter-element mechanisms. The complete detail of the proposed parallel strategy, including how to distribute the work-load, when and by what content will the collaborating processors communicate, is presented in this thesis. For conducting a flow simulation of Self-Compacting Concrete (SCC) using DEM, the element model can be a two-phase combination of arrgegate and mortar particles. The former simulates the real-world coarse aggregates, and the latter simulates the mortar solution composed of fine aggregates, water and cement. Because the mortar particles are “virtual” in the sense that they do not correspond directly to discrete mortar objects in the real world, the relationships between mechanical parameters of the mortar particles and mix proportion must be established in advance from both the results of mortar flow simulation and mortar flow tests. However, mortar flow simulations require huge computation time. Therefore, a parallel DEM program has also been developed in this research to make feasible the three-dimensional flow simulation of motar solution.致謝 i 摘要 iii Abstract v 目錄 vii 圖目錄 ix 表目錄 xiii 第1章 緒論 1 1-1 研究背景與目的 1 1-2 研究方法與步驟 7 1-3 論文組織 9 第2章 模擬工具 11 2-1 VEDO架構的優點 11 2-2 傳統離散元素法程式實作 13 2-3 VEDO架構核心類別的設計 18 2-4 VEDO架構輔助類別的設計 20 2-5 Knight&Anne 25 第3章 平行策略 27 3-1 傳統離散元素程式的平行策略 27 3-1-1 Atom Decomposition 28 3-1-2 Force Decomposition 30 3-1-3 Spatial Decomposition 32 3-2 本研究的平行策略 33 3-2-1 辨認所需的Interaction物件 36 3-2-2 處理器間交換元素作用力局部總合 40 3-2-3 同步化各元素資訊 42 3-2-4 分配Interaction物件 43 3-3 VEDO架構的擴充 54 3-4 平行效率評估 58 第4章 案例研究 75 4-1 自充填混凝土流動性質 76 4-2 砂漿流動性質的模擬方法 80 4-3 砂漿流動模擬 90 第5章 結論與建議 95 5-1 結論 95 5-2 建議 96 參考文獻 98 作者簡歷 1021507811 bytesapplication/pdfen-US離散元素法平行計算parallel computingdiscrete element methodDEMthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/50228/1/ntu-94-R92521605-1.pdf