For more information: ma.man.ac.uk/~ajuel

1. PhD projectFingering under elastic membranesSupervisor: Dr A. Juel (anne.juel@manchester.ac.uk) The interaction between elastic membranes and fluid flows is ubiquitous in many biological systems such asa living cell or even the lungs. These are very complex systems, however, so a useful physicist's approach is to seek a fundamental understanding of fluid-elastic dynamics in simpler configurations. Liquid-lined elastic tubes are good benchtop models of airways. Airways can collapse under diseased conditions and it is essential to reopen them swiftly without damaging the tissues that line them. Reopening usually occurs through the propagation of a long bubble. In our laboratory experiments on model airways1, we have discovered a novel reopening mechanism associated with the propagation of a cusped bubble that infiltrates the most collapsed part of the tube cross-section, where opposite walls are separated only by a thin film of liquid, and shear stresses are highest. This project aims to gain an understanding of this surprising mode by investigating fingering flows in a simpler geometry, i.e. under a thin fluid-lined elastic membrane. When injecting air into the elastic cell, the pressure of the bubbles increases with volumetric flow leading to growing bulges in the elastic sheet. Interesting configurations arise from the need of the sheet to return to a flat, planar geometry far ahead of the bubbles, resulting in cusped bubbles at high flow rates. This project will focus on understanding the complex interaction that arises in this configuration between flow and elastic structure, and analogies will be sought with adhesion dynamics. g R U, P Q H h Some modes of reopening in a tube Double-tipped bubble Cusped bubble 1Heap A & Juel A (2008) Anomalous bubble propagation in elastic tubes. Phys. Fluids 20, 081702. For more information: http://www.ma.man.ac.uk/~ajuel