Active Saffman-Taylor Viscous Fingering
Akash Ganesh1, Carine Douarche1, Harold Auradou1
1FAST, Université Paris-Saclay, CNRS, 91405 Orsay, France.
Abstract:
Adding swimming bacteria to a liquid causes its effective shear viscosity to decrease, eventually reaching a regime of zero viscosity. We examined whether this property leads to viscous fingerlike displacement fronts like those observed when a less viscous fluid displaces a more viscous liquid. Our study revealed that this system exhibits more complex dynamic characteristics than the classical Saffman-Taylor instability. We discovered that this instability occurs when the bacterial volume fraction exceeds a critical value and the imposed shear rate is below critical value, for which the viscosity of the suspension is zero.
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