Manchester Centre for Non-Linear Dynamics Seminars

• 1st February
  2012 Gravity currents with entrainment
  Chris Johnson (Department of Mathematics, University of Bristol)
  
  2:00 - Blackett Lecture Theatre, School of Physics and Astronomy
  Abstract (click to view)

  The term 'gravity current' is used to describe a variety of flows in which the effect of gravity on density variations in a fluid generates a horizontally spreading or propagating flow. Such currents are common in the atmosphere and oceans, where they form high-Reynolds-number turbulent flows which can be many kilometres in length but only a few metres high. This separation of scales means that depth-integrated shallow-water models provide an effective 'first-order' model of gravity currents. I will talk about some of the consequences of reducing these complex flows to shallow-water systems, and discuss one aspect of gravity currents which has received comparatively little modelling attention: the entrainment, or mixing, of ambient fluid into a current. I'll present a simple way in which entrainment can be added to a shallow-water gravity current model, and the sometimes surprising effects that this has on predictions of current behaviour.

• 29th February
  2012 The fluid dynamics of CO2 sequestration
  Jerome Neufeld (DAMTP, University of Cambridge)
  
  2:00 - Blackett Lecture Theatre, School of Physics and Astronomy
  Abstract (click to view)

  Geological storage of carbon dioxide (CO2) in deep saline aquifers forms an integral part of many CO2 mitigation strategies. At depth CO2 is buoyant and therefore may leak into surface waters or the atmosphere. This talk will explore the rich multiphase fluid dynamics of CO2 propagation, providing constraints on the rate at which CO2 may leak from a storage site, and the dynamics of convective dissolution and capillary trapping, two leading processes by which CO2 may be stably trapped and stored within the subsurface.

• 7th March
  2012 Liquid-gas phase separation in vibrated granular matter
  Michael Swift (School of Physics and Astronomy, University of Nottingham)
  
  2:00 - Blackett Lecture Theatre, School of Physics and Astronomy
  Abstract (click to view)

  We describe a novel phase transition in a non-cohesive granular gas subject to vertical vibration between two horizontal plates. We find a high-density, low temperature granular-liquid, coexisting with a low-density, high temperature granular-gas moving coherently. The mechanism responsible for the transition is traced to the existence of a negative-pressure-gradient spinodal. The dynamics of the phase separation and the existence of a non-equilibrium surface tension are also investigated.

• 14th March
  2012 Droplet flow in shallow microchannels
  Francois Gallaire (LFMI, EPFL, Lausanne, Switzerland)
  
  2:00 - Blackett Lecture Theatre, School of Physics and Astronomy
  Abstract (click to view)

  In this talk, I will first present how confined droplets flowing in microchannels can be guided and trapped by creating external surface energy gradients, either by using a focussed laser beam or by introducing depth variations. I will also present counterintuitive experiments, conducted in presence of surfactants, where thermocapillary and solutocapillary effects enter in competition, and where three-dimensional flow reversal is observed. I will then propose a two-dimensional depth-averaged model that both allows for the simulation of the droplet transport and deformation by a carrier flow and channel geometry and for Marangoni effects to be taken into account. The model will be validated against three-dimensional solutions of the creeping flow equations and then numerically implemented by a boundary element method. This work is done in collaboration with M. Nagel, R. Dangla, S. Lee and C. Baroud.

• 18th April
  2012 TBA
  Alain Goriely (Mathematical Institute, University of Oxford)
  
  2:00 - Blackett Lecture Theatre, School of Physics and Astronomy
  Abstract (click to view)

  TBA

Further information

Refreshments will be provided in the basement social area of the Schuster Lab. from 3.15pm. If you have any suggestions for future speakers, please contact Dr Draga Pihler-Puzovic.