SPH粒子初始化均布方法及其均布质量评价

光滑粒子流体动力学(SPH)是一种拉格朗日型无网格粒子法，粒子均布程度是影响SPH分析精度和稳定 性的重要因素．本文基于射线法提出了一种在异形多边形区域内均布SPH粒子的方法，先在多边形的最小外包 矩形范围内均布粒子，再通过射线法和辅助筛选条件保留区域内的粒子；通过生成粒子的Voronoi多边形计算 其变异系数值(Cv)，作为SPH粒子均布质量的评价标准，其值越小，粒子均布质量越高．为验证该方法提高分 析精度的有效性，基于爆轰侵彻的经典实验，建立由经典三角形和四边形均布粒子法构建的模型甲、模型乙和 本文模型丙，用 LS-DYNA 中的 SPH 模块进行仿真分析．研究表明，模型丙的 Cv 分别比模型甲和模型乙低 4.88 %和5.22 %；模型甲、乙和丙射流头部速度分别为5 960、5 900和6 060 m/s，较经典实验的6 100 m/s分别 相差2.3 %、3.3 %和0.7 %，相对于模型甲和模型乙，模型丙计算精度提高了1.6 %和2.6 %．因此，本文方法可 快速有效地均匀布置SPH粒子，提高分析精度

Equi-Distribution of SPH Particle Initialization and Its Quality Evaluation

Smooth particle hydrodynamics (SPH) is a Lagrangian meshless particle method. The equi-distribution quality of particles is an important factor affecting the accuracy and stability of SPH analysis. In this paper, a method of equi-distribution SPH particles in the region of heteromorphic polygon is proposed based on ray casting algorithm. Firstly, the particles are uniformly distributed in the minimum enclosing rectangular range of polygon, and then the particles are retained in the region by ray casting and auxiliary screening condition.The variation coefficient value (Cv) of the Voronoi polygon generated by the particles is calculated, which is used as the evaluation standard of SPH particle equi-distribution quality. The smaller the value is, the higher the particle equi-distribution quality will be. In order to verify the effectiveness of this method in improving the analysis accuracy, model A, model B and model C were established in this paper by the classical triangle and quadrilateral uniformly distributed particle method based on the classical experiments of detonation penetration. The SPH module in LS-DYNA was used for simulation analysis. The results show that Cv of model C is 4.88 % and 5.22 % lower than that of model A and B, respectively.The jet head velocities of model A, model B and model C are 5 960, 5 900 and 6 060 m/s respectively, which are 2.3 %, 3.3 % and 0.7 % different from those of the classical experiment of 6 100 m/s respectively. Compared with model A and model B, the accuracy of model C is improved by 1.6 % and 2.6 %, respectively. Therefore, the method presented in this paper can quickly and effectively uniformly arrange SPH particles and improve the analysis accuracy