[P-PS03] 太陽系小天体：太陽系の形成と進化における最新成果と今後の展望

[PPS03-P07] Numerical investigation on the compressive behavior of hierarchical granular piles comprising small aggregates

*荒川 創太¹、古市 幹人¹、西浦 泰介¹ (1.海洋研究開発機構)

キーワード：彗星、粉粒体

Hierarchical granular piles comprising small aggregates are ubiquitous on Earth and in space. In the context of planetary science, comets are thought to be hierarchical granular piles, and their mechanical and thermal properties have been investigated by using laboratory experiments, numerical simulations, and space exploration missions. The compressive strength of hierarchical granular piles and its filling factor dependence are of great importance to understand internal structure of comet nuclei. Laboratory experiments revealed that the response of the filling factor to compressive stress can be described by an S-shaped function (e.g., Blum et al. 2022). Hierarchical granular piles are compressed in two stages: first, the interaggregate macrostructure is compressed, and then, at higher pressures, the constituent aggregates undergo deformation and destruction.

In this study, we explore the compressive behavior of hierarchical granular piles using a numerical simulation code based on the discrete element method, DEPTH (Furuichi et al. 2018). The total number of particles in our simulations reaches up to 26,214,400, and the numerical simulations are conducted on the Earth Simulator (ES4). We successfully reproduce the two-stage compression behavior of hierarchical granular piles. Additionally, we develop a semi-analytical model based on the numerical results. These findings would help us to understand the structure evolution of small bodies in the solar system.