| Abstract: |
Dust, the material of planets, is considered to be an aggregate composed of monomers, and dust aggregates are thought to grow by collisional sticking, but their growth process remains unclear. Dust aggregate collisions have been performed using DEM (Discrete Element Method) to study the collision process and properties, such as the critical velocity, above which dust aggregates cannot grow. The results of the collisions are thought to depend on the interaction between the dust monomers. The Johnson-Kendall-Roberts (JKR) theory and the Dominik & Tielens (DT) model, which describe the forces and torques between elastic spheres, are used to simulate dust aggregate collisions. However, it has been pointed out that for small particles such as dust monomers, effects due to molecular motion appear, resulting in viscous dissipative behavior. It is essential to evaluate the effects of molecular motion because it is expected to dissipate translational kinetic energy during collisions and affect the collision results. It has also been suggested that the motion of monomers rolling on each other's surface dissipates the most kinetic energy in the collisions of dust aggregates. Then, the interaction between the monomers should be investigated based on microphysics. In this talk, I will present our work on the head-on collision process and the rolling motion of dust monomers using molecular dynamics simulations. In particular, I will discuss the influence of molecular motion by comparing it to existing contact models and present our proposed new interaction model.
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