Interface dynamics at the impact of a drop onto a deep pool of immiscible liquid

Dhuper, Karan; Guleria, Sharey Deep; Kumar, Parmod

doi:10.1016/j.ces.2021.116541

Cited by 15 publications

(7 citation statements)

References 42 publications

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“…33,34 On the other hand, a couple of experimental studies have demonstrated the impact dynamics of a spherical liquid drop onto a bath of immiscible liquid for relatively smaller impact velocities. [35][36][37]42 However, there are no reports as such where the study illustrates the post-impact flow morphologies of an immiscible droplet impacting another immiscible liquid pool at a very high velocity in the literature.…”

Section: ■ Introductionmentioning

confidence: 93%

“…In such systems, the effects of interfacial tensions alongside the density and viscosity contrasts of the fluids across the interfaces play crucial roles in determining the post-impact spatiotemporal dynamics. In this direction, a few recent numerical and experimental studies delve into improving the understanding of the ternary phase drop impacts. − For example, a number of mathematical approaches have been developed to tackle the flow details of the triplet of interfaces using the energy minimization-based finite element (FEM) and lattice-Boltzmann (LBM) methods. ,,,,, Furthermore, the post-impact flow morphologies of a ternary phase droplet impact have also been explored using a diffused interface model when the impact velocity is relatively low. , On the other hand, a couple of experimental studies have demonstrated the impact dynamics of a spherical liquid drop onto a bath of immiscible liquid for relatively smaller impact velocities. − , However, there are no reports as such where the study illustrates the post-impact flow morphologies of an immiscible droplet impacting another immiscible liquid pool at a very high velocity in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Kelvin–Helmholtz Instability Augmented by von Kármán Vortex Shedding during an Oil Droplet Impact on a Water Pool

2023

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The impact of an oil droplet on a water surface has been explored with the aid of computational fluid dynamics simulations. The study reveals the details of the spatiotemporal evolution of such a ternary system with a triplet of interfaces, e.g., air−water, oil−water, and oil−air, when the impact velocity of the oil droplet with the water surface is high. The oil droplet is found to flatten, spread, stretch, and eventually dewet on the water surface of the deep crater to show a host of interesting post-impact flow morphologies. Furthermore, at higher impact velocities, the formation of a biphasic oil−water crown is observed followed by the ejection of secondary water droplets from the crown tip due to capillary instability. The rapidly spreading oil film on the "crater" of the water surface is found to undergo Kelvin−Helmholtz instability before dewetting the same due to cohesion failure. Subsequently, the formation of an array of secondary oil droplets is observed during the process of dewetting. The dominant wavelength evaluated from the linear stability analysis of a representative flow system could faithfully predict the simulated spacing of dewetted oil droplets floating on the crater. Importantly, the variations in Laplace pressure around the curvatures of the undulatory interfaces along with sharp viscosity gradients across the three-phase contact line is found to engender interesting recirculation patterns, which eventually shed to form a coherent wake region in air near the crater. We also uncover the conditions under which the counter-rotating vortices shed along the oil−water interface resembling a von Kaŕmań vortex street.

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Section: ■ Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Kelvin–Helmholtz Instability Augmented by von Kármán Vortex Shedding during an Oil Droplet Impact on a Water Pool

2023

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“…2017; Hasegawa & Nara 2019). However, the literature of drop impacts on immiscible pools is relatively sparse (Yakhshi-Tafti, Cho & Kumar 2010; Dhuper, Guleria & Kumar 2021; Che & Matar 2018; Minami & Hasegawa 2022). Drop impacts on immiscible liquid pools are very important and is found in various industrial, engineering and natural systems.…”

Section: Introductionmentioning

confidence: 99%

On the mechanics of droplet surface crater during impact on immiscible viscous liquid pool

2023

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We study drop impacts on an immiscible viscous liquid pool and investigate the formation of droplet surface craters using experimental and theoretical analyses. We attribute the formation of air craters to the rapid deceleration of the droplet due to viscous drag force. The droplet response to the external impulsive decelerating force induces oscillatory modes on the surface exposed to the air forming capillary waves that superimpose to form air craters of various shapes and sizes. We introduce a non-dimensional parameter ( ${\varGamma }$ ), that is, the ratio of the drag force to the capillary force acting on the droplet. We show that ${\varGamma }$ is directly proportional to the capillary number. We show that droplets forming air craters of significant depths have ${\varGamma }>1$ . Further, we demonstrate that Legendre polynomials can locally approximate the central air crater jet profile. We also decipher that the air crater response time scale ( $T$ ) varies as the square root of impact Weber number ( $T\sim We^{1/2}$ ). Further, we generalize the local droplet response with a global response model for low impact energies based on an eigenvalue problem. We represent the penetrating drop as a constrained Rayleigh drop problem with a dynamic contact line. The air–water interface dynamics is analysed using an inviscid droplet deformation model for small deformation amplitudes. The local and global droplet response theories conform with each other and depict that the deformation profiles could be represented as a linear superposition of eigenmodes in Legendre polynomial basis. We unearth that the droplet response in an immiscible impact system differs from the miscible impact systems due to the presence of such a dynamic contact line.

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“…39,40 Prior art also suggests that, a few numerical models explored the metastable flow morphologies arising from the spherical oil drop impact with an air-water interface where the impact velocity is relatively low. [41][42][43][44] A couple of recent experimental studies have also observed interesting post-impact flow dynamics of a liquid droplet into a pool of immiscible fluids, [45][46][47] where the preimpact shape of the droplet is considered to be spherical. The literature discussed so far suggests that the possible alterations in the spatiotemporal dynamics of post-impact flow morphologies when a non-spherical oil droplet impacts with a quiescent air-water interface hitherto remains unexplored.…”

Section: Introductionmentioning

confidence: 99%

Influence of the pre-impact shape of an oil droplet on the post-impact flow dynamics at air–water interface

2022

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Interface dynamics at the impact of a drop onto a deep pool of immiscible liquid

Cited by 15 publications

References 42 publications

Kelvin–Helmholtz Instability Augmented by von Kármán Vortex Shedding during an Oil Droplet Impact on a Water Pool

Kelvin–Helmholtz Instability Augmented by von Kármán Vortex Shedding during an Oil Droplet Impact on a Water Pool

On the mechanics of droplet surface crater during impact on immiscible viscous liquid pool

Influence of the pre-impact shape of an oil droplet on the post-impact flow dynamics at air–water interface

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