Influence of Latent Heat in the Nasal Cavity

Abstract

Among the several functions of the nasal cavity, temperature and humidity adjustments are important for preserving the trachea and lungs. The functions of the nasal cavity have been clarified in experiments investigating the conditions in the nasal cavity. However, the difficulties of noninvasive measurements have rendered nasal cavity simulations an attractive alternative. Data are readily obtained from a simulated result. In this study, airflow, temperature, and humidity transfer in the human nasal cavity were investigated in a nasal cavity wall model of temperature and humidity transport. The simulated result was verified by comparison with experimental data. A reasonable agreement was attained between experimental data and a model incorporating the latent heat effect. The model simulates heat and water exchange in the nasal cavity. In all cases, the temperature and humidity of the inhaled air were adjusted to suitable physiological values. Temperature and humidity gradients were highest at the front of the nasal cavity. The influence of latent heat was clarified by comparing simulation results with and without latent heat under several inhaled air conditions. In the hot-humid inhaled air case, temperature in the Kiesselbach area was increased by latent heat of condensation, and relative humidity declined. In the other inhaled air cases, the temperature in the Kiesselbach area was decreased by latent heat of evaporation, while relative humidity increased. Latent heat effect was particularly influential in the hot inhaled air case.

Minor contributions of the maxillary sinus to the air-conditioning performance in macaque monkeys

“…A steady simulation is reasonable under a normal breathing frequency and flow rate in the resting stage in humans (Swift and Proctor, 1977;Hornung et al, 1987;Hahn et al, 1993;Schreck et al, 1993;Keyhani et al, 1995;Doorly et al, 2008;Kumahata et al, 2010;Hanida et al, 2013). The maximum Reynolds numbers ranged from 85 to 555 at the external nostrils in the subjects used here, calculated with estimates of the inhaled air velocity in the resting stage.…”

“…Moreover, the Womersley number for human breathing is small, thereby indicating that any inertial effects on the flow pattern may be regarded as negligible (Doorly et al, 2008;Spence et al, 2012). We used the CFD simulation model developed by Hanida et al (2013) to model an incompressible, viscid, laminar airflow in the nasal cavity with heat and water transport. The equations were solved using the fluid simulation software FLUENT 6.3 (ANSYS, Inc.).…”

“…Voxel data for the nasal cavity and MS anatomy were reconstructed from the CT scans (Kumahata et al, 2010;Hanida et al, 2013). The black areas represent air filling the nasal cavity, and the MS was extracted first using Avizo 7 (FEI Visualization Sciences Group, Hillsboro, OH, USA) based on a threshold of brightness, and the voxel data were reconstructed.…”

“…This feature is believed to have arisen independently in these lineages as the paranasal sinuses, including the MS, were lost once in a common ancestor of extant Old World monkeys (Rae et al, 2002). The performance of the air conditioning depends mainly on how the air flows through the nasal cavity (Lindemann et al, 2004;Naftali et al, 2005;Kumahata et al, 2010;Hanida et al, 2013). The structures in the nasal cavity, especially in its anterior region, have major effects on the air-conditioning performance in humans (Lindemann et al, 2004;Naftali et al, 2005;Kumahata et al, 2010;Hanida et al, 2013).…”

“…The performance of the air conditioning depends mainly on how the air flows through the nasal cavity (Lindemann et al, 2004;Naftali et al, 2005;Kumahata et al, 2010;Hanida et al, 2013). The structures in the nasal cavity, especially in its anterior region, have major effects on the air-conditioning performance in humans (Lindemann et al, 2004;Naftali et al, 2005;Kumahata et al, 2010;Hanida et al, 2013). Nevertheless, in macaques, the MS topological differences suggests it has a functional role in air conditioning (Márquez and Laitman, 2008), and the airflow in and out of the MS could affect the airflow within the nasal cavity, which has some topological differences from that in humans.…”