From splashing to bouncing: The influence of viscosity on the impact of suspension droplets on a solid surface

Schaarsberg, Martin H. Klein; Peters, Ivo R.; Stern, Menachem; Dodge, Kevin; Zhang, Wendy W.; Jaeger, Heinrich M.

doi:10.1103/physreve.93.062609

Cited by 15 publications

(8 citation statements)

References 35 publications

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“…The macrotexture causes the droplet to split after spreading, pushes the split drops away, leading the dewetting dynamics of the droplet to be quite different than what was observed on surfaces without the macrotextures. Moreover, at this higher impact velocity v = 2 m/s ( We = 71~94), splashing is observed for 0% and 40%, but not for 60% and 70% glycerol-water mixtures, due to suppression of the splashing by viscosity 52 , 53 (Fig. 5b , top).…”

Section: Resultsmentioning

confidence: 90%

Effect of superamphiphobic macrotextures on dynamics of viscous liquid droplets

Raiyan

Mclaughlin

Annavarapu

et al. 2018

Sci Rep

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The ability of hydrophobic surfaces to repel impinging liquid droplets is important in applications ranging from self-cleaning of solar panels to avoiding ice formation in freezing rain environments. In quest of maximizing water repellency, modification of droplet dynamics and subsequent reduction of contact time have been achieved by incorporating macrotexture on the superhydrophobic surfaces. However, the dynamics of low temperature water, and other viscous liquid droplets impacting anti-wetting surfaces with macrotextures is not well explored. Here, we investigate the effect of viscosity on the bouncing dynamics of liquid droplets impacting macrotextured superamphiphobic surfaces using various glycerol-water mixtures as model liquids at different impacting conditions. We demonstrate that the changes of reduction in contact times by macrotextures due to the increasing viscosity are in opposite trends at low and at high impact velocities. Since macrotexture executes substantial contact time reduction for the droplets which exhibit splitting after the impact, a preliminary model for predicting the minimum impact velocity to observe droplet splitting by macrotexture is proposed considering the important parameters of an impinging droplet along with the surface characteristics and the macrotexture size. This work aims to provide an insight on several possible outcomes of viscous droplets impacting on the macrotextured surfaces and a model that will help to design the desired superamphiphobic surfaces capable of exhibiting reduced contact time and enhanced repellency of low-temperature water droplets (such as freezing rain) and other viscous liquids (such as oils) under different impacting conditions.

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Section: Resultsmentioning

confidence: 90%

Effect of superamphiphobic macrotextures on dynamics of viscous liquid droplets

Raiyan

Mclaughlin

Annavarapu

et al. 2018

Sci Rep

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“…Since the contact angle affects the strength of the capillary force, here, differently from e.g. [33,34], the variability of the contact angle is taken into account. The bond number Bo (Equation 2), representing the ration of the capillary force to the gravitational force, is also shown along the y-axis as a function the water-ethanol fraction.…”

Section:  Rmentioning

confidence: 99%

Wet granular flow control through liquid induced cohesion

2019

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Liquid has a significant effect on the flow of wet granular assemblies. We explore the effects of liquid induced cohesion on the flow characteristics of wet granular materials. We propose a cohesion-scaling approach that enables invariant flow characteristics for different particles sizes in rotating drums. The strength of capillary forces between the particles is significantly reduced by making the glass beads hydrophobic via chemical silanization. Main results of rotating drum experiments are that liquid-induced cohesion decreases both the width of the flowing region and the velocity of the particles at the free surface, but increases the width of the creeping region as well as the dynamic angle of repose. Also, the local granular temperature in the flowing region decreases with an increase of the capillary force. The scaling methodology in the flow regimes considered (rolling and cascading regimes) yields invariant bed flow characteristics for different particle sizes.

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“…Our demonstration of the validity of the Reynolds-like dilatancy law (4.10) for flow below φ c and the identification of the non-local length scale for estimating the particle stress should help us to better understand the short-time dilation and migration dynamics of suspensions, as observed during impacts (Nicolas 2005;Peters, Xu & Jaeger 2013;Grishaev et al 2015;Boyer et al 2016;Schaarsberg et al 2016), submarine avalanches (Rondon et al 2011;Iverson 2012;Topin et al 2012;Bougouin & Lacaze 2018;Montellà et al 2021), or unsteady two-phase flows in general (Kulkarni et al 2010;Snook et al 2016;Saint-Michel et al 2019;d'Ambrosio et al 2021). For instance, the Darcy-Reynolds model was used successfully to describe the impact of a sphere on a suspension initially prepared above φ c (Jerome et al 2016).…”

Section: Discussionmentioning

confidence: 76%

Transient flows and migration in granular suspensions: key role of Reynolds-like dilatancy

et al. 2022

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We investigate the transient dynamics of a sheared suspension of neutrally buoyant particles in pressure-imposed rheology configuration, subject to a sudden change in shear rate or external pressure. Discrete element method simulations show that, depending on the flow parameters (particle and system size, initial volume fraction), the early stress response of the suspension may differ strongly from the prediction of the suspension balance model based on the steady-state rheology. We show that a two-phase model incorporating the Reynolds-like dilatancy law of Pailha & Pouliquen (J. Fluid Mech., vol. 633, 2009, pp. 115–135), which prescribes the dilation rate of the suspension over a strain scale $\gamma _0$ , captures quantitatively the suspension dilation/compaction over the whole range of parameters investigated. Together with the Darcy flow induced by the pore pressure gradient during dilation or compaction, this Reynolds-like dilatancy implies that the early stress response of the suspension is non-local, with a non-local length scale $\ell$ that scales with the particle size and diverges algebraically at jamming. In regions affected by $\ell$ , the stress level is fixed, not by the steady-state rheology, but by the Darcy fluid pressure gradient resulting from the dilation/compaction rate. Our results extend the validity of the Reynolds-like dilatancy flow rule, initially proposed for jammed suspensions, to flowing suspension below the critical volume fraction at which the suspension jams, thereby providing a unified framework to describe dilation and shear-induced migration. They pave the way for understanding more complex unsteady flows of dense suspensions, such as impacts, transient avalanches or the impulsive response of shear-thickening suspensions.

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From splashing to bouncing: The influence of viscosity on the impact of suspension droplets on a solid surface

Cited by 15 publications

References 35 publications

Effect of superamphiphobic macrotextures on dynamics of viscous liquid droplets

Effect of superamphiphobic macrotextures on dynamics of viscous liquid droplets

Wet granular flow control through liquid induced cohesion

Transient flows and migration in granular suspensions: key role of Reynolds-like dilatancy

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