Baroud, C.N., Tsikata, S. & Heil, M. (2004) The propagation of
low-viscosity fingers into fluid-filled, branching networks.
Journal of Fluid Mechanics (submitted)
We consider the motion of a finger of low-viscosity fluid as it
propagates into a branching network of fluid-filled microchannels -- a
scenario that arises in many applications, such as microfluidics,
biofluid mechanics (e.g. pulmonary airway reopening) and the flow in
porous media. We perform experiments to investigate the behaviour of the
finger as it reaches a single bifurcation and determine under what
conditions the finger branches symmetrically. We find that if the
daughter tubes have open ends, the finger branches asymmetrically and
will therefore tend to reopen a single path through the branching
network. Conversely, if the daughter tubes terminate in elastic
chambers, which provide a lumped representation of the airway wall
elasticity in the airway reopening problem, the branching is found to be
symmetric for sufficiently small propagation speeds. A mathematical
model is developed to explain the experimentally observed behaviour.
Page last modified: December 13, 2004
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