Professor Matthias Heil,
University of Manchester, United Kingdom
will give the lecture
"Wrinkly fingers" - fluid-structure interaction
in elastic-walled Hele-Shaw cells
Aarhus University, Auditorium 00.117, Dept. of Engienering,
Inge Lehmanns Gade 10, Aarhus
Abstract:
When air is injected into the narrow, liquid-filled gap between parallel rigid plates, the axisymmetrically expanding air-liquid interface tends to be unstable to non-axisym-metric perturbations. During their subsequent growth the perturbations undergo a cascade of tip-splitting instabilities which result in the development of beautiful dendritic fingering patterns.
Recent work in Manchester has shown that this widely studied classical fluid-mecha-nical instability can be weakened or even suppressed by the introduction of wall elasticity via the replacement of one of the bounding plates by an elastic membrane.
In this talk I will first explain how fluid-structure interaction weakens/suppresses the (fluid-based) fingering instability, and then demonstrate that the presence of wall elasticity can induce a second (solid-based) wrinkling instability. In certain parameter regimes, both instabilities can arise concurrently. This leads to complex interactions between the fluid and solid mechanics and results in the formation of ``wrinkly fingers”.