Modelling of immersed cantilevered plates with application to sleep-related breathing disordersSnoring and sleep apnoea are extremely common sleep-related breathing disorders having a great impact on lifestyle and health. Snoring can be the first sign of obstructive sleep apnoea (OSA), characterised by repetitive cessation of breathing. These episodes of apnoea throughout the night are due to periodic upper airway obstruction and cause sleep disruption and consequent excessive daytime sleepiness, as well as an elevated risk of accidents and cardiovascular disease. In the last few years, surgical procedures have been increasingly used to cure OSA. Such interventions altering upper airway morphology strengthen the need of a better understanding of the biomechanical phenomena involved in OSA and snoring, and of reliable predictions. The purpose of this project is to investigate the fluid-structure interactions between breathing airflow and upper airway soft-tissue, and the physical mechanisms involved in OSA and snoring.
Principal investigatorJulien Cisonni email@example.com
Area of scienceBiology, Mechanical Engineering
Applications usedOpenFOAM, oomph-lib
While the range of literature on snoring and sleep apnoea is wide, the number of studies based on FSI modelling in the upper airway remains limited. Regarding the problem of a cantilevered plate in a channel flow, the analysis of the instabilities of this idealised FSI system has many applications in different fields and is still a subject of fundamental research in the engineering community. In the context of breathing disorders, due to the complexity of the airflow and the structure of the airway, this problem becomes particularly challenging. Hence, an exhaustive parameter study of idealised FSI models relevant to snoring and OSA will permit elucidating the role of the different airway components (soft palate, uvula, pharynx, hard palate, nasal cavity) and the influence of their geometric and mechanical properties on breathing airflow and the displacement/vibration of the soft tissue.
The research project is based on the combination of idealised FSI models and anatomically-accurate representations of the upper airway. It will allow improvement of the description of the mechanisms underlying the instabilities of the soft tissue in the upper airway and of the characterisation of the sleep-related breathing disorder origins. The approach implemented will enable the identification of main morphological and biophysiological features forming the pathogenesis of the disorders and the establishment of more detailed diagnosis for particular individuals.
This study being based on parameter sweeps, access to the Magnus supercomputer is required to perform simulation runs for thousands of cases.
The accuracy needed for the predictions of the coupled solid-flow motion within 3-D airway models and idealised geometric models requires a fine mesh to discretise the geometry (several millions of cells) and a high number of iterations to numerically solve the equations.
List of Publications
Cisonni, J., Lucey, A. D. and Elliott, N. S. J. : Flutter of structurally inhomogeneous cantilevers in laminar channel flow, J Fluid Struct, under review.
Cisonni, J., Lucey, A. D. and Elliott, N. S. J. : Tapered-cantilever based fluid-structure interaction modelling of the human soft-palate, 5th Symposium on FSSIC, under review.
Figure 1. Comparison of stepped cantilever dynamic shape for different thickness ratios between the free section (blue) and clamped section (red)