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arXiv · 1705.00077

Energy invariance in capillary systems

Elfego Ruiz-Gutiérrez·James Jian Guan·Ben Xu·Glen McHale·Gary G Wells·Rodrigo Ledesma-Aguilar
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Abstract

We demonstrate the continuous translational invariance of the energy of a capillary surface in contact with reconfigurable solid boundaries. We present a theoretical approach to find the energy-invariant equilibria of spherical capillary surfaces in contact with solid boundaries of arbitrary shape and examine the implications of dynamic frictional forces upon a reconfiguration of the boundaries. Experimentally, we realise our ideas by manipulating the position of a droplet in a wedge geometry using lubricant-impregnated solid surfaces, which eliminate the contact-angle hysteresis and provide a test bed for quantifying dissipative losses out of equilibrium. Our experiments show that dissipative energy losses for an otherwise energy-invariant reconfiguration are relatively small, provided that the actuation timescale is longer than the typical relaxation timescale of the capillary surface. We discuss the wider applicability of our ideas as a pathway for liquid manipulation at no potential energy cost in low-pinning, low-friction situations.

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Elfego Ruiz-Gutiérrez, James Jian Guan, Ben Xu, Glen McHale, Gary G Wells, Rodrigo Ledesma-Aguilar. 2017-04-28. Energy invariance in capillary systems. https://doi.org/10.1103/physrevlett.118.218003

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