article published yes M. Espinosa author Vicente L Diaz Melian author b6798902-eea0-11ea-9cbc-a8e14286c631 A. Serrano-Muñoz author E. Altshuler author ScWa department When a cylindrical object penetrates granular matter near a vertical boundary, it experiences two effects: its center of mass moves horizontally away from the wall, and it rotates around its symmetry axis. Here we show experimentally that, if two identical intruders instead of one are released side-by-side near the wall, both effects are also detected. However, unexpected phenomena appear due to a cooperative dynamics between the intruders. The net horizontal distance traveled by the common center of mass of the twin intruders is much larger than that traveled by one intruder released at the same initial distance from the wall, and the rotation is also larger. The experimental results are well described by the Discrete Element Method (DEM), which reveals that, as the number of intruders horizontally released side-by-side increases, the total energy dissipation per intruder decreases. Finally, DEM simulations demonstrate that the horizontal repulsion is substantially enhanced if groups of intruders are released forming a column near the wall. Springer Nature2022 eng granular matterboundary effectsintruder penetrationsedimentation 1434-5021 1434-7636 2110.15311 00074662300000110.1007/s10035-021-01200-8 241 M. Espinosa, V. L. Diaz Melian, A. Serrano-Muñoz, and E. Altshuler, “Intruders cooperatively interact with a wall into granular matter,” <i>Granular Matter</i>, vol. 24, no. 1. Springer Nature, 2022. Espinosa, M., Diaz Melian, V. L., Serrano-Muñoz, A., &#38; Altshuler, E. (2022). Intruders cooperatively interact with a wall into granular matter. <i>Granular Matter</i>. Springer Nature. <a href="https://doi.org/10.1007/s10035-021-01200-8">https://doi.org/10.1007/s10035-021-01200-8</a> M. Espinosa, V.L. Diaz Melian, A. Serrano-Muñoz, E. Altshuler, Granular Matter 24 (2022). Espinosa, M., Vicente L Diaz Melian, A. Serrano-Muñoz, and E. Altshuler. “Intruders Cooperatively Interact with a Wall into Granular Matter.” <i>Granular Matter</i>. Springer Nature, 2022. <a href="https://doi.org/10.1007/s10035-021-01200-8">https://doi.org/10.1007/s10035-021-01200-8</a>. Espinosa M, Diaz Melian VL, Serrano-Muñoz A, Altshuler E. Intruders cooperatively interact with a wall into granular matter. <i>Granular Matter</i>. 2022;24(1). doi:<a href="https://doi.org/10.1007/s10035-021-01200-8">10.1007/s10035-021-01200-8</a> Espinosa M, Diaz Melian VL, Serrano-Muñoz A, Altshuler E. 2022. Intruders cooperatively interact with a wall into granular matter. Granular Matter. 24(1), 39. Espinosa, M., et al. “Intruders Cooperatively Interact with a Wall into Granular Matter.” <i>Granular Matter</i>, vol. 24, no. 1, 39, Springer Nature, 2022, doi:<a href="https://doi.org/10.1007/s10035-021-01200-8">10.1007/s10035-021-01200-8</a>. 107332022-02-06T23:01:30Z2023-08-02T14:10:13Z