Phenomenology and kinetics of sessile droplet evaporation on convex contours

Paul, Arnov; Dash, Rajib Kumar; Dhar, Purbarun

doi:10.1016/j.ijthermalsci.2023.108194

Cited by 8 publications

(9 citation statements)

References 39 publications

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“…Thus, we observe that the conjugate heat transfer effect plays a substantial role only when the thermal conductivity and thickness of a solid substrate are comparable with that of a liquid droplet. However, we validate the present work with our recent experimental studies [14,18] where the sessile water droplets were placed over aluminium substrates. Now, the thermal conductivity of aluminium is three order of magnitude higher than that of water.…”

Section: Formulation Of the Physical Problemsupporting

confidence: 86%

“…We vary the grid points from 89 119 to 121 852, and the maximum variation in evaporation rate was obtained as 0.06%, thereby giving grid-independent results beyond 89 119 elements. We have validated the computations with the experimental observations from our recent studies [14,18], as shown in figure 2 a,b . The numerical results closely match the experimental data for both concave and convex substrate curvatures.…”

Section: Computational Scheme and Validationsupporting

confidence: 70%

“…Also, the substrate thickness in those studies were much higher than the height of droplets. For instance, in the experimental studies [14,18] the ratio of substrate thicknesses varies in the range ls/ll≈3−12. Thus, the effect of thermal conductivities will dominate and the ratio lskl/llks∼Ofalse(10−2false).…”

Section: Formulation Of the Physical Problemmentioning

confidence: 99%

“…[35] showed that the initial transient regime solely depends on liquid properties and substrate or the ambient only play minor roles. But it is evident from our group's previous studies [18,36] that the geometrical features of the droplet–substrate system appreciably alter the evaporation mechanism of sessile droplets. Such conditions may significantly affect the associated thermo-fluidic transport.…”

Section: Introductionmentioning

confidence: 96%

“…Typically, sessile droplets evaporate mostly via constant contact angle mode on superhydrophobic (SH) flat surfaces, and by constant contact radius (CCR) mode on hydrophilic flat surfaces [16,17]. This pinning behaviour of the contact line becomes more prominent on concave substrates, while the de-pinning tendency is frequent on convex substrates [18]. This stick-slip behaviour is also significantly noticeable with increased inclination of the substrates [19].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Droplet evaporation on curved surfaces: transients of internal and external transport phenomena

Paul,

Mondal,

Dhar

2024

Proc. R. Soc. A.

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We explore the transient evolution of thermo-fluid-dynamics of evaporating sessile droplets over curved substrates in the liquid and gaseous domains. A computational model using the Arbitrary Lagrangian-Eulerian framework is adopted. The governing equations in both liquid and gaseous domains are solved in a fully coupled manner, considering coupled effects of evaporative cooling and heat advection due to bulk fluid motion. This bulk motion in the liquid domain is caused by natural advection due to thermal actuations such as thermal Marangoni flow and buoyancy-driven convection. For the gaseous domain, the additional effects of solutal convection (due to vapour-concentration variation), Stefan flow and interfacial viscous stresses are also considered. To depict a generalized role of substrate curvature, both concave and convex surfaces with curvatures over a wide range are studied. The surface wettability effects are also explored by varying the true contact angle of the droplets. Computational predictions on evaporation rate and internal flow field are validated against experimental results from literature. The interplay of wetting state and substrate curvature is noted to substantially affect the evaporation process and its thermo-fluidics. The convex curvature significantly augments internal advection while the same is weakened over concave substrates due to altered mass loss rate. Consequently, the duration of multi-vortex Marangoni flows in the development stages of evaporation and the advection in the external gaseous domain is markedly different for different curvatures. Further, on superhydrophobic curved surfaces, the effects of re-distributed evaporative fluxes play a major role. In such cases, the reduced mass flux over a large interfacial area near the periphery expedites the stable state Marangoni and external flow features.

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Section: Formulation Of the Physical Problemsupporting

confidence: 86%

Section: Computational Scheme and Validationsupporting

confidence: 70%