2013-01-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/678525摘要：受惠於現今計算技術的快速發展，工程師已越來越有機會在電腦上模擬土石流的複雜行為、並評估 其影響。然此類模擬涉及對基礎固體與流體力學的知識的理解與應用、對流體與固體間互制行為的進一 步瞭解與掌握、以及新興計算技術的整合應用。 本子計畫以離散元素法(Discrete Element Method, DEM)之理論基礎出發，配合自行發展的離散元素 模擬(Discrete Element Simulation)系統-VEDO，進一步導入計算流體動力學(Computational Fluid Dynamics, CFD)理論來擴展VEDO 系統，以完成CFD-DEM 耦合分析之土石流模擬。本研究擬使用兩種CFD 的計 算模式：晶格波茲曼法(Lattice-Boltzmann Method, LBM)與壓力隱式分割法(Pressure Implicit with Splitting of Operators, PISO)來描述流體的行為，再搭配DEM 以創造出三種不同模擬精度與計算效率的模擬方 法：(a) 單純DEM，(b) LBM-DEM，(c) PISO-DEM。此外，本子計畫團隊將以過去對平行計算技術與多 面體碰撞檢測法所累積的豐富發展與應用經驗，來提昇所發展的CFD-DEM 模擬平台的效能與擴充性。 本子計畫擬以數個數值案例，搭配子計畫五(楊馥菱教授主持)的實驗，來驗證模擬結果，案例包括： 乾濕顆粒流的崩塌行為、由暫態至穩態的混合流行為、砂湧(quick sand)現象、土壤液化(soil liquefaction) 現象、流固混合流之潰壩行為、流固混合流對結構之衝擊等。目標是要發展出一套最先進的高效能演算 法及模擬平台，來有效模擬與預測非穩定流固混合流，並應用於布唐布那斯溪的土石流模擬分析實務上。<br> Abstract: With the rapid advancement of computational power in modern IT technology, it is now feasible to simulate the complex behavior of debris flows and evaluate its influence computationally. However, realization of such a simulation requires integration of sound theoretical knowledge on solid and fluid mechanics, in-depth understanding of solid-liquid interaction behaviors, and advanced application of novel computing technologies. This subproject extends an in-house Discrete Element Simulation (DES) system, called VEDO, which is based on the Discrete Element Method (DEM), to couple with a Computational Fluid Dynamics (CFD) solver for CFD-DEM hybrid simulation of debris flow behaviors. Two CFD schemes, the Lattice-Boltzmann Method (LBM) and the Pressure Implicit with Splitting of Operators (PISO) are adopted together with DEM to provide three types of simulation approaches: (a) pure DEM, (b) LBM-DEM, and (c) PISO-DEM simulations with different levels of solution accuracy and computational efficiency, respectively. The research team of this subproject will take advantage of past experiences on application of parallel computing techniques and development of DEM solutions (e.g., method for contact detection between polyhedral in DES) to ensure high computational efficiency, software extensibility, and application flexibility of the proposed CFD-DEM simulation platform. This subproject will compare the simulation results with the experimental results from the subproject 5 (PI: Prof. F. L. Yang) using several numerical case studies on, for example, avalanche of dry and wet mixtures, transient-to-steady bulk behavior, quick sand phenomenon, soil liquefaction phenomenon, water dam breakage with solid particles, and impact of wave or particles on structure. The focus of this subproject is to develop an highly efficient simulation platform with effective algorithms for modeling and predicting unsteady solid-liquid flows that can be practically applied to simulation of the debris flow behaviors in Putunpunas canyon and its surrounding area.離散元素模擬計算流體動力學流固混合流土石流流體或顆粒對結構之衝擊Discrete Element SimulationComputational Fluid Dynamicssolid-liquid flowdebris flow優勢重點領域拔尖計畫/子計畫3-發展高效率演算法以有效模擬與預測非穩定流固混合流