Natural convection in droplet evaporation

Hegseth, John; Rashidnia, N.; Chai, A. T.

doi:10.1103/physreve.54.1640

Cited by 108 publications

(56 citation statements)

References 5 publications

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“…For a rapidly evaporating droplet, for example, the flow may be mainly generated by the Marangoni effect. 16,32 Recently, the evaporation characteristics of the water droplet were also observed and found to depend on various surrounding conditions such a) Author to whom correspondence should be addressed. Electronic mail: hclim@pusan.ac.kr Phys.…”

Section: Introductionmentioning

confidence: 99%

Evaporation-induced saline Rayleigh convection inside a colloidal droplet

et al. 2013

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Inside evaporating two-component sessile droplets, a family of the Rayleigh convection exists, driven by salinity gradient formed by evaporation of solvent and solute. In this work, the characteristic of the flow inside an axisymmetric droplet is investigated. A stretched coordinate system is employed to account for the effect of boundary movement. A scaling analysis shows that the flow velocity is proportional to the (salinity) Rayleigh number (Ras) at the small-Rayleigh-number limit. A numerical analysis for a hemispherical droplet exhibits the flow velocity is proportional to the non-dimensional number \documentclass[12pt]{minimal}\begin{document}$Ra_s^{1/2}$\end{document}Ras1/2, at high Rayleigh numbers. A self-similar condition is established for the concentration field irrespective of the Rayleigh numbers after a moderate time, and the flow field is invariant with time at this stage. The scaling relation for the high Rayleigh numbers is verified experimentally by using aqueous NaCl droplets.

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Section: Introductionmentioning

confidence: 99%

Evaporation-induced saline Rayleigh convection inside a colloidal droplet

et al. 2013

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“…-the conduction heat transfer into the wall, -the convective heat transfer induced by the surface tension gradients and the natural convection due to the temperature gradients in the liquid drop, -the liquid/wall molecular interactions, coupled with the substrate surface roughness, which tend to Hegseth (Hegseth et al 1996(Hegseth et al ) 1996 Exp. Ethanol, polystyrene particles -Chandra (Chandra et al 1996) 1996 Exp.…”

Section: Introductionmentioning

confidence: 99%

“…There are a few experimental studies that attempt to give further understanding of the drop evaporation using specific techniques. Hegseth et al (1996) and Kang et al (2003) have used PIV to visualize the fluid flow inside the drop, by charging the ethanol drop with polystyrene particles. Whilst Zhang and Chao (2001) have used a laser shadowgraphy method to visualize the fluid flow.…”

Section: Introductionmentioning

confidence: 99%

Evaporation of Ethanol Drops on a Heated Substrate Under Microgravity Conditions

Brutin

Zhu

Rahli

et al. 2010

Microgravity Sci. Technol.

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We present in this paper results obtained from a parabolic flight campaign regarding ethanol sessile drop evaporation under reduced gravity conditions. Drops are created using a syringe pump by means of injection through a PTFE (polytetrafluoroethylene) substrate. The drops are recorded using a video camera and an infrared camera to observe the thermal motion inside the drop and on the heating substrate. The experimental set-up presented in this paper enables the simultaneous visualization and access to the heat flux density that is transferred to the drop using a heat flux meter placed between the heating block and the PTFE substrate. We evidence original thermal spreading phenomena during the ethanol drop creation on a heated PTFE substrate. The drop exhibits specific behaviour which is discussed here. This work is performed in the frame of a French-Chinese collaboration (project IM-PACHT) for future experiments in a Chinese scientific satellite.

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“…18,19 Such flows are characterized by the Marangoni number Ma ≡ |dσ/dT|ΔTR/(ηα), where dσ/dT is the change of the interfacial tension with temperature, ΔT is a temperature difference, R the radius of the droplet, a the dynamic viscosity and α the thermal diffusivity. An upper bound for Ma for hexane as used in our experiments is 5, far below the critical number of 80 reported for the onset of Marangoni flows, 19 which excludes Marangoni flows as an explanation for the formation of different supraparticles. Pickering-Ramsden emulsions with nanoparticles trapped at the liquid-liquid interfaces 20,21 can also be excluded as structure-directing mechanism.…”

Section: Resultsmentioning

confidence: 99%

Pressure-controlled formation of crystalline, Janus, and core–shell supraparticles

et al. 2016

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aBinary mixtures of nanoparticles self-assemble in the confinement of evaporating oil droplets and form regular supraparticles. We demonstrate that moderate pressure differences on the order of 100 kPa change the particles' self-assembly behavior. Crystalline superlattices, Janus particles, and core-shell particle arrangements form in the same dispersions when changing the working pressure or the surfactant that sets the Laplace pressure inside the droplets. Molecular dynamics simulations confirm that pressuredependent interparticle potentials affect the self-assembly route of the confined particles. Optical spectrometry, small-angle X-ray scattering and electron microscopy are used to compare experiments and simulations and confirm that the onset of self-assembly depends on particle size and pressure. The overall formation mechanism reminds of the demixing of binary alloys with different phase diagrams.

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Natural convection in droplet evaporation

Cited by 108 publications

References 5 publications

Evaporation-induced saline Rayleigh convection inside a colloidal droplet

Evaporation-induced saline Rayleigh convection inside a colloidal droplet

Evaporation of Ethanol Drops on a Heated Substrate Under Microgravity Conditions

Pressure-controlled formation of crystalline, Janus, and core–shell supraparticles

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