Nasal Flow Simulation Using Heat and Humidity Models

The nasal cavity performs several important functions for the inhaled air, such as temperature and humidity adjustments. Although it is necessary to obtain velocity, temperature, and humidity distributions during inhalation in order to understand the nasal cavity's functions, it is difficult to measure them noninvasively in the nasal cavity. Therefore, we have continued to study nasal flow simulation with heat and humidity transport. In such a simulation, the governing equations include a continuum equation and the equations describing momentum, energy, and water transport. The temperature and humidity of the inhaled air are adjusted by heat and water exchange on the nasal cavity wall's surface. Therefore, in the simulation, these roles of the wall in the energy and water transport equations were included as the boundary conditions. Although in related studies of nasal flow simulation with heat and humidity transport, the nasal cavity wall's surface temperature and humidity were constant, here they were treated as degrees of using Newton's cooling law. A flow including temperature and humidity in a realistic human nasal cavity shape was simulated. The simulation results agreed well with the measurements reported by Keck at al. Therefore, this study concludes that our model can simulate the heat and humidity exchange occurring in the nasal cavity. In addition, it was found that the temperature and humidity adjustment functions worked effectively in the front and narrow regions of the nasal cavity.