Penetration depth scaling for impact into wet granular packings

Abstract

We present experimental measurements of penetration depths for the impact of spheres into wetted granular media. We observe that the penetration depth in the liquid saturated case scales with projectile density, size, and drop height in a fashion consistent with the scaling observed in the dry case, but with smaller penetrations. Neither viscous drag nor density effects can explain the enhancement to the stopping force. The penetration depth exhibits a complicated dependence on liquid fraction, accompanied by a change in the drop-height dependence, that must be the consequence of accompanying changes in the conformation of the liquid phase in the interstices. Disciplines Physical Sciences and Mathematics | PhysicsThis journal article is available at ScholarlyCommons: https://repository.upenn.edu/physics_papers/591PHYSICAL REVIEW E 91, 022202 (2015) Penetration depth scaling for impact into wet granular packings We present experimental measurements of penetration depths for the impact of spheres into wetted granular media. We observe that the penetration depth in the liquid saturated case scales with projectile density, size, and drop height in a fashion consistent with the scaling observed in the dry case, but with smaller penetrations. Neither viscous drag nor density effects can explain the enhancement to the stopping force. The penetration depth exhibits a complicated dependence on liquid fraction, accompanied by a change in the drop-height dependence, that must be the consequence of accompanying changes in the conformation of the liquid phase in the interstices.

Penetration in bimodal, polydisperse granular material

“…Further investigations under reduced pressure would be helpful in pinpointing how the smaller grains cause the lubrication and how important the airflow is. The impact dynamics for multicomponent granular media [14,21,22,32] appears to exhibit a complex dependence on the composition of the granular bed and therefore needs to be explored further by systematic variation of the composition and the packing fraction.…”

“…Scalings for deeper penetrations generally take the form δ/D 0 ∝ (ρ 0 /ρ g ) β (H/D 0 ) α , where both exponents are found to be dependent on the geometry of the container and, in particular, the container-to-sphere diameter ratio [20]. Recently, the effect of cohesion by mixing glass beads with water was studied [21,22], showing that the penetration depth exhibited a nonmonotonic dependence on the initial moisture content in the granular bed, whereby the cohesion from interparticle liquid bridges can play a dual role of creating a lower bulk density but also more internal friction, depending on the grain size and impact speed. In this sense, altering the composition of the bed can either "lubricate" or "stiffen" the granular bed.…”

“…In this sense, altering the composition of the bed can either "lubricate" or "stiffen" the granular bed. In this communication, we thus seek to extend the premise of lubricating the granular media [21,22] and pose the fundamental question: can smaller grains be used to lubricate the impact and increase penetration into granular material?…”

Penetration of spherical projectiles into wet granular media

“…This includes numerous empirical scaling studies for dry [2][3][4][5][6][7][8][9][10][11][12][13][14][15] and wet media [16][17][18][19][20][21], identifying the development of a network of force chains between solid grains during compression [1,12,14,15,[22][23][24], applying jamming or shear thickening models [16,25,26], and various other studies that apply macroscopic rheological models to generalize the behavior of wet sand [21,27].…”

“…We perform a small number of experiments with a second sphere size. Previous studies have considered particles that accelerate during free fall [2,[4][5][6][7]12,13,18,20,21], hence velocities less than ∼10 m/s, or very high velocities, greater than 5 km/s, to model impacts onto planetary surfaces [28]. We explore a velocity range not yet considered, but a velocity range that characterizes impacts produced by volcanic eruptions [17,29].…”