Abstract
Inspired by the recent multifluid system with thickness down to microscopic scale during thermal drawing for fiber fabrication, we perform the linear analysis of dewetting instability in multilayer planar sheets. The effects of various physical parameters on the dewetting instability have been extensively investigated, including van der Waals forces, viscosities, surface tensions, and thicknesses. As the thickness of the liquid sheet is reduced down to nanoscales, van der Waals forces become more prominent and lead to the dewetting instability. For the three-layer case (), the “para-varicose” mode with larger thickness perturbations plays a dominant role. For the four-layer case (), there are several more complicated unstable modes, and the maximum growth rate () depends on both fluid properties, and the corresponding eigenamplitudes can switch among various modes. Particularly, a slowest growth rate () is identified at a critical thickness of the cladding layer (). Additionally, for the relevant applications of fiber drawing, by changing multilayer structure from to 4 through introducing an additional less viscous sheet, the instability can be enhanced, or, by choosing a suitable thickness of a less viscous sheet, the instability can be reduced. These results not only shed light on controlling the dewetting instability by material selection and structure design, but also provide guidance to achieve functional devices with sophisticated nanostructures either in a single fiber or in integrated fabrics for large-scale textiles.
2 More- Received 22 April 2020
- Accepted 5 August 2020
DOI:https://doi.org/10.1103/PhysRevFluids.5.083904
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