LIFD Online Colloquia: Prof Anne Juel


14.00-15.00: Keynote talk from Prof Anne Juel, “Life and fate of a bubble in a geometrically-perturbed Hele-Shaw channel”

Speaker Bio: Anne Juel is a Professor in Fluid Dynamics, and heads the Fluids and Soft Matter group in the School of Physics & Astronomy. She was awarded a D. Phil from Oxford University in 1998, followed by post-doctoral positions at the Universities of Texas at Austin (USA) and Manchester (UK). She joined the School of Mathematics in 2001 and The School of Physics & Astronomy in 2014, and held an EPSRC Advanced Research Fellowship from 2005 to 2012. She is Director of the Manchester Centre for Nonlinear Dynamics (MCND), an inter-disciplinary research centre created by the Schools of Physics and Mathematics at Manchester. Research in MCND uses a multi-pronged approach that allies cutting edge mathematical and computational modelling with detailed quantitative experimental investigations into complex behaviour in fluids, soft matter and granular materials. Professor Juel has led 7 EPSRC Grants and a Leverhulme Trust Grant as PI, and her research often addresses practical applications through industrially-funded projects .

Keynote Talk Abstract: Motivated by a desire to understand complex transient behaviour in fluid flows, we study the propagation of an air bubble through a fluid-filled, geometrically-perturbed Hele-Shaw channel; a system which supports several stable modes of bubble propagation. Using experiments and numerical simulations of a depth-averaged lubrication model, we investigate the evolution of a centred bubble of fixed volume as a function of flow rate and initial shape. During its transient evolution, a bubble may undergo several topological changes in the form of breakup and coalescence, depending on parameter values. Long-term, either a single bubble is recovered or else multiple bubbles remain, whose relative separation increases with time. Despite its apparent complexity the bubbles’ transient behaviour is organised by a number of weakly unstable invariant solutions of the system, so-called edge states. An unusual feature of the system is that changes in topology due to bubble break-up or coalescence lead to changes in the invariant-solution structure during temporal evolution. Families of two-bubble and single-bubble invariant solutions can be related in the sense that their propagation speeds are identical, but there are also two-bubble solutions that do not have single-bubble equivalents. We explore how the bubble becomes increasingly sensitive to initial conditions and roughness of the channel as the flow rate increases with a view to establish the origin of the long and disordered transients observed.

Please note that this online seminar will take place via Zoom. Meeting details will be emailed to registered attendees prior to the event.