Instability in flexible channel flow

What is it about?

This paper considers a theoretical model for the flow of liquid through a vessel with flexible (elasticated) walls. In particular, it considers how the system can become unstable to self-excited oscillations - mimicking physiological phenomena such as Korotkoff noises during blood pressure measurement, wheezing in the airways and sound production by the vocal folds.

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Why is it important?

This paper considers a simplified one-dimensional system which facilitates examination of the underlying mechanism driving instability. For large external pressures the static configuration is collapsed at one point along its length. We show that the self-excited oscillation is sustained by energy released by slightly opening the point of greatest constriction over a period.