In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. ...In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. This study introduces a polyhedral Discrete Element Method (DEM) tailored for polar ice, incorporating the Gilbert-Johnson-Keerthi (GJK) and Expanding Polytope Algorithm (EPA) for contact detection. This approach facilitates the simulation of the drift and collision processes of floating ice, effectively capturing its freezing and fragmentation. Subsequently, the stability and reli ability of this model are validated by uniaxial compression on level ice fields, focusing specifically on the influence of compression strength on deformation resistance. Additionally, clusters of ice floes nav igating through narrow channels are simulated. These studies have qualitatively assessed the effects of Floe Size Distribution (FSD), initial concentration, and circularity on their flow dynamics. The higher power-law exponent values in the FSD, increased circularity, and decreased concentration are each as sociated with accelerated flow in ice floe fields. The simulation results distinctly demonstrate the con siderable impact of sea ice geometry on the movement of clusters, offering valuable insights into the complexities of polar ice dynamics.展开更多
为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dyna...为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dynamics of multi-body system,MBD)的研究方法,对双轨迹振动筛和岩屑颗粒进行联合仿真计算。探究了2种振型下筛网面上的运动轨迹与抛掷指数、筛分过程中多种岩屑颗粒的运动行为以及筛分性能。研究结果发现:变椭圆轨迹下从入料端至出料端筛面的抛掷指数和振动方向角逐渐减小,有利于实现入料端钻井液固液分离与液相透筛,降低出料端岩屑颗粒的破碎和堵筛概率;稳定筛分时,易透筛颗粒基本处于料层底部或已经透筛,难透筛和不透筛颗粒处于料层的中上层;变椭圆轨迹下多种岩屑颗粒的透筛率均高于直线轨迹、平均透筛时间均短于直线轨迹、平均运移速度均大于直线轨迹。研究成果可为钻井液振动筛的性能提升提供参考。展开更多
文摘In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. This study introduces a polyhedral Discrete Element Method (DEM) tailored for polar ice, incorporating the Gilbert-Johnson-Keerthi (GJK) and Expanding Polytope Algorithm (EPA) for contact detection. This approach facilitates the simulation of the drift and collision processes of floating ice, effectively capturing its freezing and fragmentation. Subsequently, the stability and reli ability of this model are validated by uniaxial compression on level ice fields, focusing specifically on the influence of compression strength on deformation resistance. Additionally, clusters of ice floes nav igating through narrow channels are simulated. These studies have qualitatively assessed the effects of Floe Size Distribution (FSD), initial concentration, and circularity on their flow dynamics. The higher power-law exponent values in the FSD, increased circularity, and decreased concentration are each as sociated with accelerated flow in ice floe fields. The simulation results distinctly demonstrate the con siderable impact of sea ice geometry on the movement of clusters, offering valuable insights into the complexities of polar ice dynamics.
文摘为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dynamics of multi-body system,MBD)的研究方法,对双轨迹振动筛和岩屑颗粒进行联合仿真计算。探究了2种振型下筛网面上的运动轨迹与抛掷指数、筛分过程中多种岩屑颗粒的运动行为以及筛分性能。研究结果发现:变椭圆轨迹下从入料端至出料端筛面的抛掷指数和振动方向角逐渐减小,有利于实现入料端钻井液固液分离与液相透筛,降低出料端岩屑颗粒的破碎和堵筛概率;稳定筛分时,易透筛颗粒基本处于料层底部或已经透筛,难透筛和不透筛颗粒处于料层的中上层;变椭圆轨迹下多种岩屑颗粒的透筛率均高于直线轨迹、平均透筛时间均短于直线轨迹、平均运移速度均大于直线轨迹。研究成果可为钻井液振动筛的性能提升提供参考。
