Experimental analysis on the shape and evaporation of water drops on high effusivity, microfinned surfaces

Guilizzoni, Manfredo; Sotgia, G.

doi:10.1016/j.expthermflusci.2009.09.006

Cited by 19 publications

(9 citation statements)

References 64 publications

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“…The efforts to experimentally visualize the resulting dropsurfaces interface have been, up to now, limited to non-intrusive methods (as they should not alter the system dynamics and the fluid equilibrium), usually derived from optical applications. 9 In these cases, the focal path-length, the magnification, and the medium opaque to visible wavelength emerge as major limitations, in addition to the fact that bi-dimensional images only are acquired, which may misrepresent the local information. The presence of multiple grooves can lead to significantly scattered data close to the contact line due to the prevalence of hysteresis on patterned surface, 10 and their projection on a bidimensional image yields in an unfocused region in the view parallel to the grooves.…”

Section: Introductionmentioning

confidence: 99%

A novel technique for investigation of complete and partial anisotropic wetting on structured surface by X-ray microtomography

Santini

Guilizzoni

Fest-Santini

et al. 2015

Review of Scientific Instruments

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An experimental study about the anisotropic wetting behavior of a surface patterned with parallel grooves is presented as an application example of a novel technique for investigation of complete and partial anisotropic wetting on structured surface by X-ray microtomography. Shape of glycerin droplets on such surface is investigated by X-ray micro computed tomography (microCT) acting as a non-intrusive, full volume 3D microscope with micrometric spatial resolution. The reconstructed drop volumes enable to estimate the exact volumes of the drops, their base contours, and 3D static contact angles, based on true cross-sections of the drop-surface couple. Droplet base contours are compared to approximate geometrical contour shapes proposed in the literature. Contact angles along slices parallel and perpendicular to the grooves direction are compared with each other. The effect of the sessile drop volume on the wetting behavior is discussed. The proposed technique, which is applicable for any structured surface, enables the direct measure of Wenzel ratio based on the microCT scan in the wetted region usually inapproachable by any others. Comparisons with simplified models are presented and congruence of results with respect to the minimum resolution needed is evaluated and commented.

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Section: Introductionmentioning

confidence: 99%

A novel technique for investigation of complete and partial anisotropic wetting on structured surface by X-ray microtomography

Santini

Guilizzoni

Fest-Santini

et al. 2015

Review of Scientific Instruments

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“…Evaporation from porous media is of great interest to numerous industrial applications including the drying of agricultural and pharmaceutical products, light oil recovery, soil remediation, construction [23], drop or spray deposition in industrial, agricultural and biomedical environments and the cooling of metallic and ceramic surfaces and of electronic devices [21]. Several experimental studies [24,25] and theoretical models [24,25], [26] were developed to understand solvent evaporation from three-dimensional pore networks.…”

Section: Introductionmentioning

confidence: 99%

“…Although the spreading and wetting topic is meticulosity presented, the problematic of evaporation from the pores is not discussed. Also the wetting at nanometer scale raises the necessity to investigate the flow of liquids inside nanochannels, as channel wettability plays an integral role in the flow of liquids through it[21]. A coherent theoretical framework relating wettability to fluid flow in nanochannels is still missing despite a large number of experimental papers having been published[22].The capillarity of nanotubes is directly related to the surface energies of interaction between the liquid and the solid surface.…”

mentioning

confidence: 99%

Liquid droplet evaporation from buckypaper: On the fundamental properties of the evaporation profile

Schuszter

Bogya

Horváth

et al. 2015

Microporous and Mesoporous Materials

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“…The impact dynamics of liquid drops on groove-textured solid surfaces has received academic interest in recent years in view of their anisotropic wettability behavior. [23][24][25][26] On a groove-textured solid surface, the spreading and receding processes of the drop liquid in the direction perpendicular to the grooves involve pinning and depinning of the drop contact line at the edges of the pillar posts. [27][28][29][30][31] As observed on micro-textured solid surfaces, [9][10][11][12][13][14][15][16] an impacting drop on a given groove-textured solid surface undergoes the transition from the Cassie to an impaled state (in which at least one of the roughness asperities underneath the drop is impaled by the drop liquid) at a particular drop impact velocity, referred to here as the critical drop impact velocity, depending on the groovetexture geometry and forces acting on the drop liquid at the edges of asperity posts beneath it.…”

Section: Introductionmentioning

confidence: 99%

Transition from Cassie to impaled state during drop impact on groove-textured solid surfaces

Vaikuntanathan

Sivakumar

2014

Soft Matter

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Liquid drops impacted on textured surfaces undergo a transition from the Cassie state characterized by the presence of air pockets inside the roughness valleys below the drop to an impaled state with at least one of the roughness valleys filled with drop liquid. This occurs when the drop impact velocity exceeds a particular value referred to as the critical impact velocity. The present study investigates such a transition process during water drop impact on surfaces textured with unidirectional parallel grooves referred to as groove-textured surfaces. The process of liquid impalement into a groove in the vicinity of drop impact through de-pinning of the three-phase contact line (TPCL) beneath the drop as well as the critical impact velocity were identified experimentally from high speed video recordings of water drop impact on six different groove-textured surfaces made from intrinsically hydrophilic (stainless steel) as well as intrinsically hydrophobic (PDMS and rough aluminum) materials. The surface energy of various 2-D configurations of liquid-vapor interface beneath the drop near the drop impact point was theoretically investigated to identify the locally stable configurations and establish a pathway for the liquid impalement process. A force balance analysis performed on the liquid-vapor interface configuration just prior to TPCL de-pinning provided an expression for the critical drop impact velocity, Uo,cr, beyond which the drop state transitions from the Cassie to an impaled state. The theoretical model predicts that Uo,cr increases with the increase in pillar side angle, α, and intrinsic hydrophobicity whereas it decreases with the increase in groove top width, w, of the groove-textured surface. The quantitative predictions of the theoretical model were found to show good agreement with the experimental measurements of Uo,cr plotted against the surface texture geometry factor in our model, {tan(α/2)/w}(0.5).

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Experimental analysis on the shape and evaporation of water drops on high effusivity, microfinned surfaces

Cited by 19 publications

References 64 publications

A novel technique for investigation of complete and partial anisotropic wetting on structured surface by X-ray microtomography

A novel technique for investigation of complete and partial anisotropic wetting on structured surface by X-ray microtomography

Liquid droplet evaporation from buckypaper: On the fundamental properties of the evaporation profile

Transition from Cassie to impaled state during drop impact on groove-textured solid surfaces

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