title: Penetration of spherical projectiles into wet granular media.
abstract: We measure experimentally the penetration depth d of spherical particles into a water-saturated granular medium made of much smaller sand-sized grains. We vary the density, size R, and velocity U of the impacting spheres, and the size δ of the grains in the granular medium. We consider velocities between 7 and 107 m/s, a range not previously addressed, but relevant for impacts produced by volcanic eruptions. We find that d∝R(1/3)δ(1/3)U(2/3). The scaling with velocity is similar to that identified in previous, low-velocity collisions, but it also depends on the size of the grains in the granular medium. We develop a model, consistent with the observed scaling, in which the energy dissipation is dominated by the work required to rearrange grains along a network of force chains in the granular medium.
authors.affiliation: Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York 14853-6801, USA and Department of Earth and Planetary Science, University of California Berkeley, Berkeley, California 94720-4767, USA.
authors.forename: S P D
authors.initials: SP
authors.lastname: Birch
authors.affiliation: Department of Earth and Planetary Science, University of California Berkeley, Berkeley, California 94720-4767, USA.
authors.forename: M
authors.initials: M
authors.lastname: Manga
authors.affiliation: Department of Earth and Planetary Science, University of California Berkeley, Berkeley, California 94720-4767, USA.
authors.forename: B
authors.initials: B
authors.lastname: Delbridge
authors.affiliation: Department of Earth and Planetary Science, University of California Berkeley, Berkeley, California 94720-4767, USA.
authors.forename: M
authors.initials: M
authors.lastname: Chamberlain
mesh_terms: D008962:Models, Theoretical; D009038:Motion; D010316:Particle Size; D013816:Thermodynamics; D014867:Water
chemical_list: D014867:Water