流星进入的可变形不规则离散元分析方法

New meteoroid entry method with a deformable non-spherical N-body model

流星进入地球大气层时会发生空中解体和爆炸,威胁地球局部区域乃至全球安全针对流星进入大气演化的超高速动力学仿真研究具有重要意义.为提高预报的精确性,应关注流星体内部结构和非均匀烧蚀等对演化过程和解体后碎片运动的影响。本文提出了一种可变形不规则离散元方法,用于仿真分析流星进入大气层时轨迹和姿态变化、烧蚀、解体和爆轰等现象。利用多面体离散元模型可模拟不同结构的异质流星;通过拉伸多面体模型顶点,仿真流星的粗糙外形和烧蚀形变;利用Jones-Wilkins-Lee状态方程计算烧蚀产生的集中爆轰产物的压力.以Chelyabinsk流星事件中发生轨迹偏离的碎片为例,数值仿真集中爆轰产物的膨胀驱动作用对碎片运动方向和轨迹演化的影响.仿真结果表明,碎片弹出轨迹特征和烧蚀剩余质量均在观测值范围内,验证了新方法的有效性.

Meteoroid disintegration in the atmosphere can produce airbursts that pose regional/global threats to the Earth.Precise dynamical simulation of hypersonic meteoroids is necessary for human safety.An analysis model that includes spatial structures and non-uniform ablation is needed to understand the evolution of meteoroids and provide inference for the deviation of fragments.This paper proposes a new meteoroid entry method to simulate their trajectory,attitude,ablation,fragmentation,and detonation.N-body configurations of deformable polyhedral granules that can alter the structures of heterogeneous meteoroids are introduced.By manipulating the polyhedron vertices,the rugged surfaces of the meteoroid and the volume change under ablation are described quantitatively.The pressure of the concentrated detonation products is modeled using the Jones-Wilkins-Lee equation of state.To verify the effectiveness of the new method,the expansion of the concentrated detonation products is numerically simulated for the Chelyabinsk meteoroid.Different detonation cases are obtained and presented to demonstrate the laterally/vertically-ejected fragments.Characteristics of both the fragments'trajectories and the remained terminal masses satisfy the observed results well.