Étude informatique de la dynamique de l’air lors du cycle respiratoire dans les cavités naso-sinusiennes adultes

Abstract : Background: despite some limitations, computational fluid dynamic (CFD) simulations have improved understanding of complex nasal anatomy and physiology. However, CFD protocols to date are heterogeneous. We postulate that simulation of the entire respiratory nasal cycle is mandatory to observe and understand airflow. The aim of this study was to perform CFD simulation within the whole sino-nasal cavities and during the complete and repeated respiratory cycle. Materials and methods: a 3D sino-nasal model was constructed from a healthy adult high-resolution CT scan. The 3D mesh contained around 6.6 million cells with a mean volume of 0.008 mm3 (ANSYS©TGridTMv16.0.0). CFD simulations were performed with ANSYS©FluentTMv16.0.0 software. Sino-nasal walls were defined to be rigid and no-slip. Simulations of transient airflow were carried out by applying sinusoidal flow rate variations corresponding to a ventilation rate of 30 L/min. Two cycles of respiration of a total duration of 8s were simulated. Time advancement was discretized in 1.0 ms time steps. Sino-nasal pressure variations, velocity contours and particle residence time were assessed. Results: there was a pressure gradient within the sinus cavities according to their place of connection to the depth of the nasal cavity and the direction of airflow. Alternation of the pressure gradient during the respiratory cycles created a mild pumping phenomenon close to the ostia. However, there was no or only mild movement within the sinus cavities during the respiratory cycle. Concerning the velocity contours, the main airflow was accelerated by the nasal valve. Its decelerated as it passed the turbinate bodies and reaccelerated close to the turbinate tails. Surprisingly, the inferior meatus did not fill during inspiration but did during expiration through its posterior entrance, as did the olfactory cleft at the same time. During the respiratory cycle, the anatomical structures did not seem to play the same role in the coming and going of air. Finally, particle residence time was considerably increased during expiration because the particles were retained by the nasal valve, as if the expiratory phase were preparing the next inspiratory phase. Particles steadily accumulated close to the inferior turbinates, the posterior part of the olfactory cleft and on both sides of the main airflow at the site of turbulence. This pattern increased as the respiratory cycle was repeated. Conclusion: CFD simulation is an efficient tool for understanding the complexity of the sino-nasal cavities in normal and pathologic conditions and should be used more in daily practice. The respiratory cycle must be simulated completely and repeated to avoid any loss of information.
Document type :
Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-01628044
Contributor : Bu Carreire Université de Bordeaux <>
Submitted on : Thursday, November 2, 2017 - 6:34:44 PM
Last modification on : Saturday, November 25, 2017 - 1:24:09 AM

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Nicolas Réville. Étude informatique de la dynamique de l’air lors du cycle respiratoire dans les cavités naso-sinusiennes adultes. Médecine humaine et pathologie. 2017. ⟨dumas-01628044⟩

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