Nonlinear Sound Propagation in Granular Media (SOUND)

abstract

Sound propagation in granular systems is a complex wave phenomena (e.g., multiple sound scattering, nonlinear acoustics), but also it may be used as a non-invasive tool to probe the packing structure and the mechanical properties [1-2]. Under weak compression and relatively strong excitation, the nonlinear nature of particle interaction becomes very important and is reflected by a transition of the propagation regime. Numerical simulation showed that the wave speed increases with the excitation amplitude according to a power law dependence [3]. This dependence is a trademark of the soliton-like shock wave in the highly nonlinear regime and was later partially verified by ground experiments [4]. The current limitation of such experiments is that the weight of the particles always causes some compression of the system, and a marginal or unjammed state proposed in [3] can not be reached for three-dimensional systems. Low gravity condition in this case becomes essential to realize this highly nonlinear regime. Therefore we propose building a nonlinear sound excitation and detection setup for low gravity facilities to fully investigate the wave speed and the dissipation under close-to-zero compression.

• [1] C. Liu and S. R. Nagel, "Sound in sand", Phys. Rev. Lett., vol. 68, pp. 2301-2304, Apr. 1992.
• [2] X. Jia, C. Caroli, and B. Velicky, "Ultrasound propagation in externally stressed granular media", Phy. Rev. Lett., vol. 82, pp. 1863-1866, Mar. 1999.
• [3] L. R. Gomez, A. M. Turner, M. van Hecke, and V. Vitelli, "Shocks near Jamming", Phys. Rev. Lett., vol. 108, pp. 058001, Jan. 2012.
• [4] S. van den Wildenberg, R. van Loo, and M. van Hecke, "Shock waves in weakly compressed granular media", Phys. Rev. Lett. 111, 218003, Nov. 2013

experiment year: 2017
number of catapult launches: 10

experiment year: 2015
number of catapult launches: 2
number of drops: 6

experiment year: 2014
number of catapult launches: 8