Impact cratering on a granular bed by hydrogel spheres having intermediate property between solid and liquid

Matsuda, Yu; Fukui, Satoru; Kamiya, Ryota; Yamaguchi, Hiroki; Niimi, Tomohide

doi:10.1103/physreve.99.032906

Cited by 9 publications

(7 citation statements)

References 19 publications

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“…force F, as shown in figure 1(b). Now, the Young's modulus Y of the sphere may be determined using the Hertz theory for the deformation of an elastic sphere (Matsuda et al 2019):…”

Section: Experimental Methodsmentioning

confidence: 99%

“…a highly deformable, elastic sphere. Matsuda et al (2019) performed impact experiments onto granular media with packing fraction of 0.618 using elastic hydrogel spheres with a Young's modulus of several kilopascals, the results of which indicate that the crater diameter obeys a power law in the impact kinetic energy with exponent 0.223 when the maximum deformation is smaller than 30 % of the sphere's diameter, and 0.205 for larger maximum deformations, thus indicating a value that, while it is still consistent with solid-sphere impact, lies between those for solid and liquid impactors mentioned above.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogel sphere impact cratering, spreading and bouncing on granular media

Meer

2021

J. Fluid Mech.

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The impact of a hydrogel sphere onto a granular target results in both the deformation of the sphere and the formation of a prominent topographic feature known as an impact crater on the granular surface. We investigate the crater formation and scaling, together with the spreading diameter and post-impact dynamics of spheres by performing a series of experiments, varying the Young's modulus $Y$ and impact speed $U_{0}$ of the hydrogel spheres, and the packing fraction and grain size of the granular target. We determine how the crater diameter and depth depend on $Y$ and show the data to be consistent with those from earlier experiments using droplets and hard spheres. Most specifically, we find that the crater diameter data are consistent with a power law, where the power exponent changes more sharply when $Y$ becomes less than 200 Pa. Next, we introduce an estimate for the portion of the impact kinetic energy that is stored as elastic energy during impact, and thus correct the energy that remains available for crater formation. Subsequently, we determine the deformation of the hydrogel spheres and find that the normalized spreading diameter data are well collapsed introducing an equivalent velocity from an energy balance of the initial kinetic energy against surface and elastic energy. Finally, we observe that under certain intermediate values for the Young's modulus and impact velocities, the particles rebound from the impact crater. We determine the phase diagram and explain our findings from a comparison of the elastocapillary spreading time and the impact duration.

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“…force F, as shown in figure 1(b). Now, the Young's modulus Y of the sphere may be determined using the Hertz theory for the deformation of an elastic sphere (Matsuda et al 2019):…”

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrogel sphere impact cratering, spreading and bouncing on granular media

Meer

2021

J. Fluid Mech.

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“…This indicates that these soft gel spheres act as elastic materials, and we can use the Hertz theory for deformation of an elastic sphere to determine the Young's modulus (Supplemental Eq. 7) 32,34,37 , which in turn can be used to approximate the shear modulus G for the spheres (assuming Poisson's ratio ν = 0.5 under the incompressibility condition). G has values that range in between 6 KPa to 8 KPa, quantifying the softness of the spheres (see supplemental section 0.5 for detailed analysis of G).…”

Section: Dmentioning

confidence: 99%

“…3/2 power law typical for Hertz theory for a linear isotropic elastic sphere. The experimental fit (green dashed line) can then be used to determine the Young's modulus of the sphere material by employing the relation below 37 ,…”

Section: Binary Drop Experimentsmentioning

confidence: 99%

Droplet lift-off from hydrophobic surfaces from impact with soft-hydrogel spheres

Rabbi¹,

Kiyama²,

Allen³

et al. 2021

Preprint

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Droplet impacts on superhydrophobic surfaces may result in complete bouncing, with the absence of contact hysteresis and viscous dissipation leading the droplet to fully rebound off the surface. This rebound usually happens in the retraction phase, when the droplet retracts back after reaching a maximum spread diameter. Here, we present experimental evidence of a novel bouncing phenomenon where a sessile droplet on a hydrophobic surface bounces off the surface in its spreading phase when a soft deformable hydrogel sphere axisymmetrically impacts the droplet. We term this as 'Lift-Off' and propose a simple force balance based on the deformation characteristics of the hydrogel sphere to explain the out-of-plane jump of the droplet during spreading. We observe three different impact regimes, and propose their dependency on a modified elastic 'Mach' number (Ma*) with (Ma*)=0.2 corresponding to the onset of lift-off. We also report on the unique acoustic signatures of lift-off cases, associated with the capture of air-bubbles through the air-borne retracting droplet rim. Concerning the novel lift-off results, this work may have potential applications for drainage and surface cleaning, non-stick surface coating, industrial mixing and plant disease spreading.

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“…The ball indentation technique is a very common method used, for instance, for evaluating hardness and tensile properties of continuum-solids, particularly for assessing the integrity of metallic structures [11,12,13], or for studying the process of formation and the morphology of planetary and lunar craters [14,15,16,17]. The same method has recently been proposed by Hassanpour and Ghadiri for evaluating the flowability of cohesive bulk powders at low compaction levels, in quasi-static conditions and at small scales [18].…”

Section: Introductionmentioning

confidence: 99%