Continuum dynamics of elastocapillary coalescence and arrest
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Abstract
The surface-tension–driven coalescence of wet hair, nano-pillars and supported lamellae immersed in an evaporating liquid is eventually arrested elastically. To characterize this at
a continuum level, we start from a discrete microscopic model of the process and derive a mesoscopic theory that couples the inhomogeneous dynamics of drying to the capillary forcing and
elastic bending of the lamellae. Numerical simulations of the resulting partial differential equation capture the primary unstable mode seen in experiments, and the dynamic coalescence of the
lamellae into dimers and quadrimers. Our theory also predicts the elastic arrest of the pattern
or the separation of lamellar bundles into their constituents as a function of the amount of liquid
left at the end of the process.