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Viscous fingering and dendritic growth under an elastic membrane
Published online by Cambridge University Press: 02 August 2017
Abstract
We present an experimental investigation of interfacial fingering instabilities in a compliant channel, where the interface can adopt a planar front orthogonal to the direction of propagation over most of the channel width. Finite-length fingers develop on that front, similarly to the previously studied radial configuration with injection of air at constant flow rate (Pihler-Puzović et al., Phys. Rev. Lett., vol. 108 (7), 2012, 074502), but, unlike the radial case, the interface propagates steadily. This allows us to present the first quantification of the nonlinearly saturated fingering pattern and to demonstrate that the morphological features of the fingers are selected in a simple way by the local geometry of the compliant cell. In contrast, the local geometry itself is determined from a complex fluid–solid interaction. Furthermore, we find that changes to the geometry of the channel cross-section lead to a rich variety of possible interfacial patterns.
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- © 2017 Cambridge University Press
References
Ducloué et al. supplementary movie 1
Aerial view of an air finger steadily propagating under a latex membrane (b=210 μm) topping a partially occluded channel. The fingers regularly split, maintaining a constant average width and length. Block dimensions: 30 mm wide and 900 μm high; h = 150 μm. The video has been slowed down four times.
Ducloué et al. supplementary movie 2
Side view of an air finger propagating under a thin (b = 100 μm) silicone membrane. The transparent membrane has been dusted with fine powder to make the laser line visible (bright line). The straight section of interface propagating on the block does not undergo fingering. Block dimensions: 30 mm wide and 900 μm high; h = 150 μm. The video has been slowed down twice.
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