Research Areas

Fine particles, such as virus-containing aerosols and particulate matter (PM) from air pollution, penetrate the human respiratory system. These disease-causing particles are transported into and deposited within the lungs at various locations, depending on the flow structure. Therefore, understanding respiratory flow has a fundamental importance in relation to respiratory diseases caused by fine particles. However, respiratory flow is difficult to analyze due to various issues such as the complex geometry of the lungs, fluid-structure interaction, and three-phase flows (i.e. particles, droplets, and air). There is a limitation in examining these types of flows using optical diagnostics, due to the difficulty in obtaining optical access for the narrow and twisted channels. Therefore, we are applying magnetic resonance velocimetry (MRV) using medical MRI scanners to observe the internal flow structure of the respiratory system. MRV enables non-intrusive 3D measurement of the flow structure inside these narrow flow paths. Using these results, we further aim at predicting the effect of flow structure on the distribution of particles inside the respiratory tract. We also hope to elucidate how the particles affect respiratory diseases depending on their concentration, size, material, etc.

Figure 1. (a) Flow rate calculated from MRV data. The blue circle is the peak point of inhalation. (b) Velocity contours with vectors at the ① nasal vestibule, ② turbinate, and ③ nasopharynx.