For problems in astrophysics, planetary science and beyond, numerical simulations are often limited to simulating fewer particles than in the real system. To model collisions, the simulated particles (aka superparticles) need to be inflated to represent a collectively large collisional cross section of real particles. Here we develop a superparticle-based method that replicates the kinetic energy loss during real-world collisions, implement it in an $N$-body code and test it. The tests provide interesting insights into dynamics of self gravitating collisional systems. They show how particle systems evolve over several free fall timescales to form central concentrations and equilibrated outer shells. The superparticle method can be extended to account for the accretional growth of objects during inelastic mergers.

中文翻译：

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模拟碰撞的超粒子方法

对于天体物理学、行星科学及其他领域的问题，数值模拟通常仅限于模拟比真实系统中更少的粒子。为了模拟碰撞，模拟粒子（又名超粒子）需要膨胀以表示真实粒子的整体大碰撞截面。在这里，我们开发了一种基于超粒子的方法，该方法可以复制真实世界碰撞期间的动能损失，在 $N$-body 代码中实现它并对其进行测试。这些测试提供了对自引力碰撞系统动力学的有趣见解。它们展示了粒子系统如何在几个自由落体时间尺度上演化以形成中心浓度和平衡外壳。超粒子方法可以扩展到解释非弹性合并过程中物体的增生增长。