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Etude numérique et expérimentale de l'écoulement nasal dans des géométries réalistes

Abstract : The inspiratory gas flow in nasal Upper Airways (UA) is studied in steady conditions both experimentally and numerically using three geometries selected for their highly realistic character: a post mortem nasal geometry obtained from a plastinated head, and two UA geometries (“healthy” and “pathological”) obtained in vivo from tomodensitometric data of patients. The model of plastinated nose is also scanned and its geometry numerically reconstructed in 3D. The numerical study (CFD computation) consists in solving Navier-Stokes equations in each 3D reconstructed geometry after facetization (Amira) and generation of different volumetric meshes (Amira ou Gambit TGrid), in laminar and/or turbulent regimes and inspiratory flow rates up to 1 L/s. The experimental study consists in measuring the relationship between pressure drop and flow rate up to 1.5 L/s between the entry region of the nose and the outlet of UA, on the plastinated nose model and on the physical model of healthy UA obtained by stereolitography. After defining the characteristics sections in each model based on anatomical and mechanical criteria, the central axis is defined by segments as a line joining the median point in each section and their validation is performed using the acoustic reflection method in the plastinated nose model. Results concerns: (i) the experimental - numerical comparison using the global pressure drop in two models showing a discrepancy smaller than 10% up to a flow rate of 0.4 L/s; (ii) the comparative characterization of three geometries from the evolution along the nasal axis of values of area, the hydraulic diameter and local Reynolds number; (iii) the relative magnitude of the three streams associated to the turbinates, (iv) the pressure drops and kinetic energy variation versus Reynolds number defined globally or by segments. On the whole, the results reveal the highly complex character of the nasal flow. Although nasal flow is essentially laminar, it is perturbed by the rapid succession of geometrical changes along the nasal axis. Although plastinated nose model exhibit a similarity between right - left nostril flows, in vivo geometry do not likely due to vasomotors phenomena. This study confirms the interest of using CFD in proper reconstructed nasal geometry of patients.
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https://tel.archives-ouvertes.fr/tel-00116937
Contributor : Céline Croce <>
Submitted on : Friday, March 9, 2007 - 3:42:48 AM
Last modification on : Friday, October 23, 2020 - 4:52:39 PM
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Céline Croce. Etude numérique et expérimentale de l'écoulement nasal dans des géométries réalistes. Sciences du Vivant [q-bio]. Université Paris XII Val de Marne, 2006. Français. ⟨tel-00116937v2⟩

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