On the selection of Saffman-Taylor viscous fingers for divergent flow in a wedge

Fuente: arXiv
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Autori principali: Andersen, Cecile, Lustri, Christopher J., McCue, Scott W., Trinh, Philippe H.
Natura: Preprint
Pubblicazione: 2024
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author Andersen, Cecile
Lustri, Christopher J.
McCue, Scott W.
Trinh, Philippe H.
author_facet Andersen, Cecile
Lustri, Christopher J.
McCue, Scott W.
Trinh, Philippe H.
contents We study self-similar viscous fingering for the case of divergent flow within a wedge-shaped Hele-Shaw cell. Previous authors have conjectured the existence of a countably-infinite number of selected solutions, each distinguished by a different value of the relative finger angle. Interestingly, the associated solution branches have been posited to merge and disappear in pairs as the surface tension decreases. We demonstrate how exponential asymptotics is used to derive the selection mechanism. In addition, asymptotic predictions of the finger-to-wedge angle are given for different sized wedges and surface-tension values. The merging of solution branches is explained; this feature is qualitatively different to the case of classic Saffman-Taylor viscous fingering in a parallel channel configuration. The phenomena of branch merging in our self-similar problem relates to tip splitting instabilities in time-dependent flows in a circular geometry, where the viscous fingers destabilise and divide in two.
format Preprint
id arxiv_https___arxiv_org_abs_2403_08671
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the selection of Saffman-Taylor viscous fingers for divergent flow in a wedge
Andersen, Cecile
Lustri, Christopher J.
McCue, Scott W.
Trinh, Philippe H.
Fluid Dynamics
We study self-similar viscous fingering for the case of divergent flow within a wedge-shaped Hele-Shaw cell. Previous authors have conjectured the existence of a countably-infinite number of selected solutions, each distinguished by a different value of the relative finger angle. Interestingly, the associated solution branches have been posited to merge and disappear in pairs as the surface tension decreases. We demonstrate how exponential asymptotics is used to derive the selection mechanism. In addition, asymptotic predictions of the finger-to-wedge angle are given for different sized wedges and surface-tension values. The merging of solution branches is explained; this feature is qualitatively different to the case of classic Saffman-Taylor viscous fingering in a parallel channel configuration. The phenomena of branch merging in our self-similar problem relates to tip splitting instabilities in time-dependent flows in a circular geometry, where the viscous fingers destabilise and divide in two.
title On the selection of Saffman-Taylor viscous fingers for divergent flow in a wedge
topic Fluid Dynamics
url https://arxiv.org/abs/2403.08671