[P-PS02] Regolith Science

[PPS02-03] Energetics of P and S waves in lightly confined granular columns

*Vasu Paliwal¹, Hiroaki Katsuragi², Ishan Sharma³ (1.Department of Mechanical Engineering, IIT Kanpur, Kanpur, India, 2.Department of Earth and Space Science, Osaka University, Osaka, Japan, 3.Department of Mechanical Engineering; Department of Space, Planetary & Astronomical Sciences & Engineering, IIT Kanpur, Kanpur, India)

Keywords:Asteroids, N-body Simulations, Regolith, Planetary Structure

Waves in lightly confined granular media find application in extraterrestrial scenarios involving small bodies like asteroids, where the gravitational pressures may be as low as a few pascals, as in the case of Itokawa. We report findings from discrete element (DE) simulations of pressure (P) and shear (S) wave transmissions through very lightly confined granular columns. We consider both monodisperse and bidisperse granular aggregates. Waves are excited in various ways, e.g. by a continuously driven wall at one end of the column, a short pulse, or a sinusoidal input. Our DE simulations are conducted on LAMMPS and were validated at higher pressures against experiments, as well as simulations on P waves [Sánchez, P, DJ Scheeres and AC Quillen 2022. Transmission of a seismic wave generated by impacts on granular asteroids. Planet. Sci. J. 3: 245]. An important finding is that shear waves do not sustain through the length of the granular column and, in fact, transition into pressure waves.