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arXiv · 1805.02998

Peristaltic elastic instability in an inflated cylindrical channel

Nontawit Cheewaruangroj·Karolis Leonavicius·Shankar Srinivas·John S. Biggins
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Abstract

A long cylindrical cavity through a soft solid forms a soft microfluidic channel, or models a vascular capillary. We observe experimentally that, when such a channel bears a pressurized fluid, it first dilates homogeneously, but then becomes unstable to a peristaltic elastic instability. We combine theory and numerics to fully characterize the instability in a channel through a bulk neo-Hookean solid, showing that instability occurs supercritically with wavelength $2π/k=12.278....a$ when the pressure exceeds $2.052....μ$. In finite solids, the threshold pressure is reduced, and peristalsis is followed by a second instability which shears the peristaltic shape breaking axisymmetry. These instabilities shows that, counterintuitively, if a pipe runs through a bulk solid, the bulk solid can be destabilizing rather than stabilizing at high pressures. They also offers a route to fabricate periodically undulating channels, producing waveguides with photonic/phononic stop bands.

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Nontawit Cheewaruangroj, Karolis Leonavicius, Shankar Srinivas, John S. Biggins. 2018-05-08. Peristaltic elastic instability in an inflated cylindrical channel. https://doi.org/10.1103/physrevlett.122.068003

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