Fluid-structure interactions in the human upper airway — large-displacement biomechanics
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Obstructive breathing disorders, such as sleep apnoea and snoring, interfere with normal respiration and sleep, reducing brain-oxygen saturation and are linked with hypertension and heart failure. The mechanics of the human upper airway are characterised by the interaction of the low-stiffness structures, being the soft palate and throat sidewalls, with the air flow producing soft-tissue vibrations that may lead to airway closure. In order to investigate this dynamical system we employ a cantilevered flexible plate (soft-palate) immersed in a two-dimensional channel (pharynx) flow. For this canonical analogue, we take the next step towards biomechanical realism by modelling finite-amplitude motions of the flexible plate and incorporating finite thickness in its structure. The structural model makes use of a geometrically nonlinear formulation of the solid mechanics. Viscous flow is modelled at Reynolds numbers giving unsteady laminar flow. The fully-coupled fluid-structure interaction (FSI) model is developed using the open-source finite-element library oomph-lib. We begin with a validation study of the structural mechanics through examining the effects of finite amplitude and finite thickness on the in-vacuo modes. Thereafter, we use the FSI model to illustrate both stable and unstable motions of the plate.This paper demonstrates the versatility of the new modelling approach and its suitability for characterising the dependence of the plate’s stability on the system parameters.
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Elliott, Novak; Lucey, Anthony; Eastwood, P.; Hillman, D.; Heil, M. (2011)Snoring noise is generated by vibration of the soft tissues of the upper airway, principally those that form the back of the roof of the mouth (the soft palate) and its conical extension (the uvula). In addition to discord ...
Large-Amplitude Oscillations of a Finite-Thickness Cantilevered Flexible Plate in Viscous Channel FlowElliott, Novak; Lucey, Anthony; Heil, M. (2010)The broad aim of the present work is to elucidate mechanisms of obstructive breathing disorders (snoring, sleep apnea) in which flow-induced instabilities of the soft palate feature. We use the well-established analogue ...
Tetlow, George A. (2012)Repetitive closure of the upper-airway characterises obstructive sleep apnea. It disrupts sleep causing excessive daytime drowsiness, and is linked to hypertension and cardiovascular disease.Previous studies simulating ...