Viscous fingering: from suppression to disorder.

by Prof. Anne Juel

Tuesday 27 Oct 2020, 15:00 → 17:00 Europe/Stockholm

Join Zoom Meeting
https://stockholmuniversity.zoom.us/j/622224375

Meeting ID: 622 224 375

 

What links a baby’s first breath to adhesive debonding, enhanced oil recovery,
filtration or multiphase microfluidics? These processes involve two-phase
displacement flows in rigid or elastic confined vessels, which are prone to
interfacial instabilities. The canonical viscous fingering instability, which
occurs when air displaces a viscous fluid in the narrow gap between two
parallel plates, provides a versatile test-bed for such phenomena. In this
talk, I will use both experiments and numerical simulations of depth-averaged
models to explore several aspects of viscous fingering. I will first show how
the onset of fingering can be suppressed when replacing the upper plate of the
vessel with an elastic sheet. Interfacial flows in narrow gaps can also exhibit
considerable disorder, but they are rarely investigated from a dynamical
systems perspective. I will show how compliance can promote rich multiplicity
of front propagation modes in a channel, including disordered and therefore
transient dynamics. I will then turn to exploring how organised transient
dynamics of bubbles propagating in a rigid channel are orchestrated by
weakly-unstable steady propagation modes, which can appear and disappear as the
number of bubbles changes through bubble break-up and coalescence.