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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

WETTING AND EVAPORATION OF OCTAGONAL SALINE DROPLETS ON A MICROPYRAMID PATTERNED SURFACE

Get access (open in a dialog) DOI: 10.1615/IHTC16.mtr.023441
pages 5827-5832

要約

Droplet dynamics on surfaces are of vital importance to the designs and manipulations of chip manufacturing, biological and medical science, and thermal management. Droplet shape control has been extensively realized by engineering surfaces with structures, e.g. pillars with different density, geometry and arrangement. In this study, we propose a low-cost approach by simply varying the salt potassium chloride (KCl) concentration in the droplet solution to control the droplet shape on poly(methyl methacrylate) substrates fabricated with micropyramid islands. The droplets with various salt concentrations exhibit octagonal shapes on the micropyramid substrate. The octagonal solid-liquid interface varies toward a rectangle with corners cut by increasing the initial salt concentration. The physical mechanism behind the dependence of the solid-liquid interface on the salt concentration is interpreted by analyzing the free energy difference at the contact line. The saline droplets are found to experience a pinning and then a depinning stage during the lifetimes. During the depinning stage the wetting interface evolves toward a circle and the octagonal shape is lost.