Experimental investigation into the impact of a liquid droplet onto a granular bed using three-dimensional, time-resolved, particle tracking

Abstract

(2014) 'Experimental investigation into the impact of a liquid droplet onto a granular bed using three-dimensional, time-resolved, particle tracking.', Physical review E., 89 (3). 032201.Further information on publisher's website:http://dx.doi.org/10.1103/PhysRevE.89.032201Publisher's copyright statement:Reprinted with permission from the American Physical Society: Physical Review E 89, 032201 c 2014 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. An experimental investigation into the interaction that occurs between an impacting water droplet and a granular bed of loose graded sand has been carried out. High-speed imaging, three-dimensional time-resolved particle tracking, and photogrammetric surface profiling have been used to examine individual impact events. The focus of the study is the quantification and trajectory analysis of the particles ejected from the sand bed, along with measurement of the change in bed morphology. The results from the experiments have detailed two distinct mechanisms of particle ejection: the ejection of water-encapsulated particles from the edge of the wetted region and the ejection of dry sand from the periphery of the impact crater. That the process occurs by these two distinct mechanisms has hitherto been unobserved. Presented in the paper are distributions of the particle ejection velocities, angles, and transport distances for both mechanisms. The ejected water-encapsulated particles, which are few in number, are characterized by low ejection angles and high ejection velocities, leading to large transport distances; the ejected dry particles, which are much greater in number, are characterized by high ejection angles and low velocities, leading to lower transport distances. From the particle ejection data, the momentum of the individual ballistic sand particles has been calculated; it was found that only 2% of the water-droplet momentum at impact is transferred to the ballistic sand particles. In addition to the particle tracking, surface profiling of the granular bed postimpact has provided detailed information on its morphology; these data hav...

Granular impact cratering by liquid drops: Understanding raindrop imprints through an analogy to asteroid strikes

“…The fraction of energy for ejecting particles is then E eject ≡ f · E, with f < 1 automatically satisfied by construction. E eject is consistent with recent experiments that estimate the momentum of ejected particles (21). Finally, an energy scaling argument similar to that used for solid-sphere impacts can be applied: instead of E, E eject lifts granular particles in a crater of volume V c to a height determined by d c , i.e., E eject ≈ ϕρ sand V c gd c , where ϕ = 0:60 is the volume fraction of the bed and ρ sand is the particle density.…”

“…Here, d c is the depth of crater, defined as the vertical distance between the rim and the bottom floor of the crater. Previous studies reported the depth of crater in the presence of granular residues (17,21), which, however, does not reflect the true bottom of a crater underneath the granular residues. Here, to detect d c without the optical obstruction of granular residues in the center of crater, we focus on the range of E where the liquid marble bounces off the surface (Fig.…”

“…Although several recent experiments have been attempted to investigate the morphology of liquid-drop impact craters (17)(18)(19)(20)(21), a coherent picture for describing various features of the impact craters is still lacking. Even for the most straightforward impact-energy (E) dependence of the size of liquid-drop impact craters, the results remain controversial and incomplete (17,19,20).…”

Sediment connectivity: a framework for understanding sediment transfer at multiple scales

“…For example, detachment by raindrop impact is a relatively inefficient process. Long et al (2014) have estimated that only 2-4 % of raindrop-impact momentum is transferred to movement as splash. As shallow, surface flows start to occur, the effects of rainfall and flow energy initially combine (Parsons et al, 1993), but then as the flow depth increases the energy reaching the bed from raindrop impact exponentially decreases (Torri et al, 1987) so by then, flow detachment dominates (Parsons et al,.…”

The impact of raindrops on sand

“…It is only in the last decade, that drop impact on sand started to draw the attention of physicists, with studies focused on rain showers [12,13] or single drop impact [14][15][16][17][18][19][20][21].…”