以離散元素法及計算流體力學雙向耦合模擬顆粒體在液體儲槽內的卸載流動行為

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Title:	以離散元素法及計算流體力學雙向耦合模擬顆粒體在液體儲槽內的卸載流動行為
Authors:	蕭佑衡;Hsiao, Yu-Heng
Contributors:	機械工程學系
Keywords:	雙向流耦合未解析法離散元素法與計算流體力學;液體中儲槽顆粒體卸載行為;阻力模型;液體黏滯性;置入物;粒子溫度;Unresolved CFD-DEM;granular silo flows in liquid;drag models;liquid viscosity;inserts;granular temperature
Date:	2024-10-04
Issue Date:	2025-04-09 18:24:28 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究採用未解析法的計算流體力學與離散元素法雙向流耦(Unresolved CFD-DEM)模擬顆粒體在液體儲槽中卸載的流動行為，探討在不同流體阻力模型、液體黏滯係數與儲槽置入物對顆粒體流動行為的影響，進一步分析顆粒體在液體儲槽中的速度分布、粒子溫度、擾動速度分布與容器中底部壓力分佈。研究結果顯示：(1) 三種阻力模型Di Felice、Gidaspow, Bezburuah & Ding與Wen & Yu model的結果差異性甚微；(2)顆粒體在液體中卸載速度隨液體黏滯性越高而越小，且顆粒流速越大造成的粒子溫度也越大；(3)容器底部壓力僅在高黏滯性液體與較大儲槽開口發生壓降現象；(4)顆粒體卸載速度隨置入物安裝位置越高而越快，擾度速度分布隨置入物安裝位置越低而越集中；(5)儲槽置入物高度，對顆粒體卸載的流動行為影響甚微；(6)顆粒體卸載速度隨置入物寬度越寬而越小；(7)顆粒體卸載過程末端質量流率上升主要由顆粒間碰撞接觸力增加所引起，末端質量流率上升越顯著顆粒粒子溫度越大。;This study employs an unresolved Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach to simulate the discharge behavior of granular materials in storage silos submerged in liquid. It investigates the effects of various drag models, liquid viscosity, and silo inserts on granular silo flows. Furthermore, the explored physical properties include the velocity distribution of the granular material, granular temperature, fluctuating velocity distribution, and pressure distribution at the bottom of the container. The major findings are summarized below: (1) The differences among the three drag models—Di Felice, Gidaspow, Bezburuah & Ding, and Wen & Yu—are minimal in the scenario studied here; (2) The discharge velocity of the granular materials in the liquid decreases as liquid viscosity increases, and higher granular flow velocity results in higher granular temperatures; (3) Pressure deep at the bottom of the container occurs only in high-viscosity liquids and with larger silo openings; (4) The discharge velocity of the granular materials increases with higher insert positions, while the fluctuating velocity distribution becomes more concentrated with lower insert positions; (5) The height of the silo insert has a minimal impact on the discharge flow behavior of the granular materials; (6) The discharge velocity of the granular materials decreases as the width of the insert increases; (7) The increase in mass flow rate near the end of the discharge process is primarily due to the increased contact force between colliding particles, and the greater the increase in mass flow rate, the higher the granular temperature.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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