Collision of a droplet with a hemispherical static droplet on a solid

Fujimoto, Hitoshi; Ogino, Tomoyuki; Takuda, Hirohiko; Hatta, Natsuo

doi:10.1016/s0301-9322(00)00075-6

Cited by 82 publications

(38 citation statements)

References 16 publications

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“…Regardless of this, most previous studies in droplet deposition have focused only on the external dynamics-e.g., the freesurface shape, extent of spreading, and final footprint of the composite droplet [8][9][10][11][12][13]-and only a few works have explored the internal dynamics or mixing [5,7,14,15].…”

Section: Introductionmentioning

confidence: 99%

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

et al. 2013

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The coalescence and mixing of a sessile and an impacting liquid droplet on a solid surface are studied experimentally and numerically in terms of lateral separation and droplet speed. Two droplet generators are used to produce differently colored droplets. Two high-speed imaging systems are used to investigate the impact and coalescence of the droplets in color from a side view with a simultaneous gray-scale view from below. Millimeter-sized droplets were used with dynamical conditions, based on the Reynolds and Weber numbers, relevant to microfluidics and commercial inkjet printing. Experimental measurements of advancing and receding static contact angles are used to calibrate a contact angle hysteresis model within a lattice Boltzmann framework, which is shown to capture the observed dynamics qualitatively and the final droplet configuration quantitatively. Our results show that no detectable mixing occurs during impact and coalescence of similar-sized droplets, but when the sessile droplet is sufficiently larger than the impacting droplet vortex ring generation can be observed. Finally we show how a gradient of wettability on the substrate can potentially enhance mixing.

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Section: Introductionmentioning

confidence: 99%

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

et al. 2013

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“…Manservisi and Scardovelli [5] proposed a finite element method coupled with the interface front-tracking method to investigate the motion of a droplet on horizontal surfaces with different wettability. Fujimoto et al [6] also investigated the collision of a droplet with a hemispherical droplet on a solid surface by experimental and numerical approaches. From their results, it is found that a circular liquid crown appears due to a large pressure gradient near the free surface.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of dynamic behavior of droplet on solid surface by the two-phase lattice Boltzmann method

et al. 2011

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The dynamic behavior of a droplet on a solid surface is simulated by the lattice Boltzmann method (LBM) for two-phase fluids with large density differences; the wetting boundary condition on solid walls is incorporated in this simulation. By using the method, the dynamic behavior of a droplet impinging on a horizontal wall is investigated in terms of various Weber numbers. The dynamic contact angle, the contact line velocity, and the wet length are calculated, and found to be in good agreement with available experimental data. In addition, the method is applied to simulations of the collision of a falling droplet with a stationary droplet on a solid surface. The * Corresponding author. Tel.:+81 26 269 5116; fax:+81 26 269 5116.Email address: masato@shinshu-u.ac.jp (M. Yoshino) 1 Present address: Seiko Epson Corporation, Suwa-shi, Nagano 392-8502, Japan.

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“…Changes in SCA of lapacho wood remained between ~8 and ~15% (Figure 3), while SCA did not vary statistically after plasma treatments (Table 1). This was expected, since different characteristics influence SCA, such as contact angle, droplet diameter, speed of impact and surface roughness (Chandra et al 1996;Fujimoto et al 2001;Kannangara and Shen 2008;Wang et al 2009). From an industrial processing standpoint, the experimental observations in the present paper confirm the feasibility of applying plasma treatment to improve wettability of tropical wood flooring surfaces, and consequently can help to improve the quality of finishing steps.…”

Section: Resultsmentioning

confidence: 95%

Surface wettability of Brazilian tropical wood flooring treated with He plasma

Cademartori

Nisgoski

Magalhães

et al. 2016

Maderas, Cienc. tecnol.

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This study investigated the effect of plasma treatment on changes of surface wettability of wood flooring from two Brazilian tropical species, Hymenaea spp. (rode locus) and Tabebuia spp. (lapacho). Wood flooring samples were plasma treated at low pressure in a helium atmosphere. Energy level was set at 100 W and four glow discharge times (5, 15, 30 and 45 s) were tested. Changes in wettability were investigated by measuring apparent contact angle, droplet volume and spreading contact area. The results showed less susceptibility of lapacho wood to the plasma treatments, while reduction of apparent contact angle in rode locus wood reached up to 76% for longer discharge times. In general, discharge time of 15 s produced the same effect as discharge of 45 s on wettability, which is important for industrial applications. Visual analyses revealed increase of water droplet spreading on lapacho wood surface, even though the variation of spreading contact area was not significant. Plasma treatment is feasible to improve wettability of tropical woods. Nevertheless, these findings should be investigated further due to the intrinsic characteristics of woods from tropical species.

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Collision of a droplet with a hemispherical static droplet on a solid

Cited by 82 publications

References 16 publications

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

Numerical simulation of dynamic behavior of droplet on solid surface by the two-phase lattice Boltzmann method

Surface wettability of Brazilian tropical wood flooring treated with He plasma

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