Droplet impact on a dry surface: triggering the splash with a small obstacle

Josserand, Christophe; Moyne, Luis Le; Troeger, R.; Zaleski, Stéphane

doi:10.1017/s0022112004002393

Cited by 75 publications

(45 citation statements)

References 30 publications

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“…9 In other papers, the authors apparently refer interchangeably to the central part of the lamella and the curved end where surface tension acts. 8,[10][11][12] c͒ measurements of the rim thickness, which we report here, can be viewed as constraints on possible simplified models. Despite the theoretical predictions and relevance of the lamella thickness to understanding both spreading and splashing phenomena, there have been relatively few direct measurements, particularly at the time scale relevant for splashing.…”

Section: Introductionmentioning

confidence: 84%

“…It is common in recent theories of splashing to assume that the lamella thickness is proportional to the thickness, ͱ t, of a viscous boundary layer, where is the kinematic viscosity of the liquid and t is the time after impact. [8][9][10][11][12] This same idea has also been used for film thickness after impact on a thin liquid film. 13 A functional form for the lamella thickness is also essential for theories of film spreading after droplet impact.…”

Section: Introductionmentioning

confidence: 99%

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Thickness of the rim of an expanding lamella near the splash threshold

2010

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The evolution of the ejected liquid sheet, or lamella, created after impact of a liquid drop onto a solid surface is studied using high-speed video in order to observe the detailed time evolution of the thickness of the rim of the lamella. Since it has been suggested that splashing behavior is set at very early times after impact, we study early times up to D 0 / U 0 , where D 0 and U 0 are the diameter and speed of the impacting drop, respectively, for different liquid viscosities and impact speeds below the splashing threshold. Within the regime of our experiments, our results are not consistent with the idea that the lamella rim grows similar to the boundary layer thickness. Rather, we find that the rim thickness is always much larger than the boundary layer thickness, and that the rim thickness decreases with increasing impact speed. For lower impact speeds, the increase in the rim thickness is consistent with a ͱ t response over the limited time range available, but the dependence is not simply proportional to ͱ , where is the kinematic viscosity, and there is a strong dependence of the rim thickness on the impact speed U 0 . Scaling of the rim height using a balance of inertial and surface tension forces provides some collapse of the data at lower impact speeds. We also observe an unusual plateau behavior in thickness versus time at higher impact speeds as we approach the splash threshold.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Thickness of the rim of an expanding lamella near the splash threshold

2010

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“…The influence of the substrate on the spreading and splashing has been studied in [126,[137][138][139][140][141]. Recent research by Nagel's and Brenner's groups has identified that the compressibility of the gas, here air surrounding the droplet [142,143] affects the splashing.…”

Section: An Example Of Current Capabilities Of Computational Fluid Dymentioning

confidence: 99%

Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

Attinger

Moore

Donaldson

et al. 2013

Forensic Science International

154

139

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This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses. Keywordsbloodstain pattern analysis, review, dimensionless number, drop generation, trajectory, impact, stain Disciplines Laboratory and Basic Science Research | Other Mechanical EngineeringComments NOTICE: this is the author's version of a work that was accepted for publication in Forensic Science International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Forensic Science International, [231, 1-3, (2013) Abstract: This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses.

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“…However, some authors have looked at smooth solid substrates containing a single obstacle (Delbos et al 2010;Ding & Theofanous 2012;Lorenceau & Quéré 2003;Roisman et al 2010;Josserand et al 2005), e.g., the impact of a droplet near an open-ended hole (pore), revealing different flow behaviour depending on the impact location. For a centred impact, the inner part of the droplet will enter the pore and the remaining liquid will spread (Delbos et al 2010;Ding & Theofanous 2012).…”

Section: Introductionmentioning

confidence: 99%

Exploring droplet impact near a millimetre-sized hole: comparing a closed pit with an open-ended pore

2015

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We investigate drop impact dynamics near closed pits and open-ended pores experimentally. The resulting impact phenomena differ greatly in each case. For a pit, we observe three distinct phenomena, which we denote as: a splash, a jet and an air bubble, whose appearance depends on the distance between impact location and pit. Furthermore, we found that splash velocities can reach up to seven times the impact velocity. Drop impact near a pore, however, results solely in splashing. Interestingly, two distinct and disconnected splashing regimes occur, with a region of planar spreading in-between. For pores, splashes are less pronounced than in the pit case. We state that, for the pit case, the presence of air inside it plays the crucial role of promoting splashing and allowing for air bubbles to appear.

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Droplet impact on a dry surface: triggering the splash with a small obstacle

Cited by 75 publications

References 30 publications

Thickness of the rim of an expanding lamella near the splash threshold

Thickness of the rim of an expanding lamella near the splash threshold

Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

Exploring droplet impact near a millimetre-sized hole: comparing a closed pit with an open-ended pore

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