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arXiv · 1704.08399

Spreading law on a completely wettable spherical substrate: The energy balance approach

Masao Iwamatsu
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Abstract

The spreading of a cap-shaped spherical droplet on a completely wettable spherical substrate is studied. The non-equilibrium thermodynamic formulation is used to derive the thermodynamic driving force of spreading including the line-tension effect. Then the energy balance approach is adopted to derive the evolution equation of the spreading droplet. The time evolution of the contact angle $θ$ of a droplet obeys a power law $θ\sim t^{-α}$ with the exponent $α$, which is different from that derived from Tanner's law on a flat substrate. Furthermore, the line tension must be positive to promote complete wetting on a spherical substrate, while it must be negative on a flat substrate.

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Masao Iwamatsu. 2017-04-27. Spreading law on a completely wettable spherical substrate: The energy balance approach. https://doi.org/10.1103/physreve.95.052802

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