Liquid Bridges in Non-Axisymmetrically Buckled Elastic Tubes: Conclusions.

Detailed computational parameter studies lead to the following conclusions:
  1. For sufficiently large surface tensions, the compressive load exerted by the liquid bridge on the tube wall is strong enough to make it buckle non-axisymmetrically.
  2. For many combinations of the control parameters (external pressure and surface tension) multiple buckled equilibrium configurations exist.
  3. Many of these equilibrium configurations are statically unstable. If perturbed slightly, the system would collapse into an even more strongly collapsed state.
  4. For physiologically realistic parameter values [given by Halpern & Grotberg: `Fluid-Elastic Instabilities of Liquid-Lined Flexible tubes.' Journal of Fluid Mechanics 244, 615-632 (1992)], we predict the airway walls to collapse very strongly.
  5. The fluid volume required to form an occluding liquid bridge in a non-axisymmetrically buckled tube can be as low as 10% of the minimal liquid bridge volume in an axisymmetric tube.
  6. For sufficiently high surface tension buckling takes place in multiple modes (as observed physiologically) and the loss of stability of the axisymmetric configuration is followed by a `catastrophic' collapse into a strongly deformed configuration with opposite wall contact in which the fluid contained in the initial axisymmetric liquid bridge gets spread out along the tube.

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Page last modified: September 29, 2000

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