Granular impact drag force and its material-dependent scaling


Experimental result of the granular impact dynamics for various kinds of projectiles and granular media will be reported. The granular impact drag force can be modeled by the sum of inertial drag and frictional drag [1]. In this study, we investigate the material properties dependence of the coefficients in the drag force model [2]. Spherical or cylindrical projectiles are dropped onto non-cohesive dry granular media, and their deceleration processes are captured precisely. Using those dynamic data, we find material-dependent scaling for the granular impact stopping force which consists of inertial and frictional drag. The inertial drag scaling is similar to fluids. However, the frictional drag scaling cannot be explained by the combination of hydrostatic pressure and Coulomb friction law. The frictional drag scales as square-root of the density of granular medium and projectile.

[1] H. Katsuragi and D. J. Durian, Nat. Phys. 3, 420, (2007).
[2] H. Katsuragi and D. J. Durian, arXiv:1304.4212, (2013).

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