Air-conditioning characteristics of the human nose

Wolf, Michael; Naftali, Sara; Schroter, R. C.; Elad, David

doi:10.1258/002221504772784504

Cited by 80 publications

(65 citation statements)

References 34 publications

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“…In addition, the same authors found that a high increase of humidity and temperature was found in the anterior nasal segment and that further increase of both parameters between the turbinate area and nasopharynx was less pronounced in spite of the longer distance (Keck et al, 2000a). A review paper by Wolf et al (2004) also discussed the air-conditioning characteristics of the human nose through results of in-vivo, in-vitro and computational simulations. It is noted that the computational simulations were based on simplified models of the nasal cavity.…”

Section: Introductionmentioning

confidence: 97%

From CT Scans to CFD Modelling – Fluid and Heat Transfer in a Realistic Human Nasal Cavity

Inthavong

Wen

et al. 2009

Engineering Applications of Computational Fluid Mechanics

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ABSTRACT:The air conditioning capability of the nose is dependent on the nasal mucosal temperature and the airflow dynamics caused by the airway geometry. A computational model of a human nasal cavity obtained through CT scans was produced and the process described. CFD techniques were applied to study the effects of morphological differences in the left and right nasal cavities on the airflow and heat transfer of inhaled air. A laminar steady flow of 15 L/min was applied and two inhalation conditions were investigated: normal air conditions, 25°C, 35% relative humidity and cold dry air conditions, 12°C, 13% relative humidity. It was found that the frontal regions of the nasal cavity exhibited greater secondary cross flows compared to the middle and back regions. The left cavity in the front region had a smaller cross-sectional area compared to the right which allowed greater heating as the heat source from the wall was closer to the bulk flow regions. Additionally it was found that the role of the turbinates to condition the air may not be solely reliant on the surface area contact but may in fact be influenced by the nature of the flow that the turbinates cause.

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Section: Introductionmentioning

confidence: 97%

From CT Scans to CFD Modelling – Fluid and Heat Transfer in a Realistic Human Nasal Cavity

Inthavong

Wen

et al. 2009

Engineering Applications of Computational Fluid Mechanics

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“…Though each task separately constitutes a difficult challenge, the nose attains a remarkable level of performance in all three. Firstly, inspired air largely attains body temperature and saturation before reaching the glottis (Mygind & Dahl 1998;Wolf et al 2004). Secondly, although olfactory sensitivity depends on a host of factors, including the particular odorant molecule, threshold values for olfactory detection in the low tens of parts per billion have been reported (Walker et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Inflow boundary profile prescription for numerical simulation of nasal airflow

Taylor

Doorly

Schroter

2009

J. R. Soc. Interface.

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Knowledge of how air flows through the nasal passages relies heavily on model studies, as the complexity and relative inaccessibility of the anatomy prevents detailed in vivo measurement. Almost all models to date fail to incorporate the geometry of the external nose, instead employing a truncated inflow. Typically, flow is specified to enter the model domain either directly at the nares (nostrils), or via an artificial pipe inflow tract attached to the nares. This study investigates the effect of the inflow geometry on flow predictions during steady nasal inspiration. Models that fully replicate the internal and external nasal airways of two anatomically distinct subjects are used as a reference to compare the effects of common inflow treatments on physiologically relevant quantities including regional wall shear stress and particle residence time distributions. Inflow geometry truncation is found to affect flow predictions significantly, though slightly less so for the subject displaying more pronounced passage area contraction up to the internal nasal valve. For both subject geometries, a tapered pipe inflow provides a better approximation to the natural inflow than a blunt velocity profile applied to the nares. Computational modelling issues are also briefly outlined, by comparing quantities predicted using different surface tessellations, and by evaluation of domain-splitting techniques.

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Section: Introductionmentioning

confidence: 99%

“…The nasal cavity serves three principal roles: (i) it warms and humidifies inspired air, (ii) it protects and defends the lower respiratory tract by filtering particles and trapping some pathogens, and (iii) it houses the olfactory receptors [2,3]. Filtration of particles involves deposition on the cavity walls or on the nasopharynx with nearly all particles greater than 5µm and about 50% of those 2 − 4µm captured while the majority of particles smaller than 2µm bypass the nose [2]. Air-conditioning involves both heating and humidifying the air on inspiration (23 o C, 40% relative humidity at the nares to 33 o C, 98% relative humidity) while recapturing some heat and humidity on expiration (37 o C, 98% relative humidity to 33 o C, 85% relative humidity at the nares, resulting in ∼ 100ml of water per day being saved) [2].…”

Section: Introductionmentioning

confidence: 99%

“…Filtration of particles involves deposition on the cavity walls or on the nasopharynx with nearly all particles greater than 5µm and about 50% of those 2 − 4µm captured while the majority of particles smaller than 2µm bypass the nose [2]. Air-conditioning involves both heating and humidifying the air on inspiration (23 o C, 40% relative humidity at the nares to 33 o C, 98% relative humidity) while recapturing some heat and humidity on expiration (37 o C, 98% relative humidity to 33 o C, 85% relative humidity at the nares, resulting in ∼ 100ml of water per day being saved) [2]. The olfactory receptors are concentrated in the olfactory cleft, in the superior and posterior region of the cavity [4].…”

Section: Introductionmentioning

confidence: 99%

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Modelling nasal airflow using a Fourier descriptor representation of geometry

Gambaruto

Taylor

Doorly

2008

Numerical Methods in Fluids

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. SUMMARYProcedures capable of providing both compact representations and rational simplifications of complex anatomical flow conduits are essential to explore how form and function are related in the respiratory, cardiovascular and other physiological flow systems. This work focuses on flow in the human nasal cavity. Methods to derive the cavity wall boundary from medical images are first outlined. Anisotropic smoothing of the boundary surface is shown to provide less geometric distortion in regions of high curvature, such as at the ends of the narrow nasal passages. A reversible decomposition of the surface into a stack of planar contours is then effected using an implicit function formulation. Fourier descriptors provide a continuous representation of each contour as a modal expansion, and permit simplification of the geometry by retaining only dominant modes via filtering.Computations of the steady inspiratory flow field are performed for replica and reduced geometries, where the reduced geometry is derived by retaining only the first fifteen modes in the expansion of each slice contour. The overall pressure drop and integrated wall shear are shown to be virtually unaffected by simplification. More sensitive measures, such as the Lagrangian particle trajectories and residence time distributions show slight changes as discussed.Comparison of the Fourier descriptor method applied to three different patient data sets indicate the potential of the technique as a means to characterise complex flow conduit geometry, and the scope for further work is outlined.

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Air-conditioning characteristics of the human nose

Cited by 80 publications

References 34 publications

From CT Scans to CFD Modelling – Fluid and Heat Transfer in a Realistic Human Nasal Cavity

From CT Scans to CFD Modelling – Fluid and Heat Transfer in a Realistic Human Nasal Cavity

Inflow boundary profile prescription for numerical simulation of nasal airflow

Modelling nasal airflow using a Fourier descriptor representation of geometry

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