Influence of particle rotation on the oblique penetration in granular media

The rotation of a particle has significant influence on the dynamic response of a granular bed subjected to the oblique impact of a spherical projectile. Based on the discrete element method, the dynamical behavior of two-dimensional granular media impacted obliquely by rotating particles has been examined in this work, especially for the influence of rotational angular velocity on its penetration depth. The simulations show that the incident rotational velocity will not only act on the characteristics of velocity distribution of the bed after impacting, but also influence the trajectory of the projectile qualitatively. For low angular velocities, particle rotations will significantly increase the vertical penetration depths, while the different directions of rotation will exert opposite effects on the horizontal penetration depths. In addition, the influence of particle rotation on its penetration depth will be enhanced with increasing angular velocity, but such effect will reach an asymptotic plateau for sufficiently large angular velocities. This indicates that the angular velocity has an obvious criticality. Furthermore, the variation of critical angular velocity may be linear with the impact velocity and square with the impacting angle, approximately. Finally, the influence of the initial particle rotation on the scaling law of penetration depth is also considered, and we find that the linear scaling with impact velocity is still applicable for most impact conditions.