Numerical Simulation for Intranasal Transport Phenomena

More than 10million people in Japan suffer some of nasal diseases every year (Haruna (2003)); the paranasal sinusitis (so-called the empyema), hypertrophic rhinitis and inferior concha inflammation. Nebulizer treatment has been used for the nasal diseases. The effectiveness of the nebulizer treatment has been confirmed from clinical view points until now. However there are a few researches that evaluate the effect of the nebulizer treatment theoretically and quantitatively, i.e., the transport characteristics of medicinal droplets and their deposition on the inflammation areas of nasal wall. The development of medical image processing technique is in progress and now gives us exquisitely detailed anatomic information. Some researchers calculated blood flow inside vital arteries and intranasal airflow characteristics by means of the medical image processing technique as well as Computed Fluid Dynamics (CFD) analysis. As for the CFD analysis of intranasal flow, Weinhold et al. constructed both a transparent resin model and numerical three-dimensional anatomy model with nasal cavities using a patient’s CT data (Weinhold & Mlynski (2004)). They subsequently made clear airflow characteristics in the nose experimentally and numerically, and found that pressure drop was a main factor of nasal airflow. Lindemann et al. focused at a case which underwent radical sinus surgery (Lindemann et al. (2004; 2005)). In their case, both the lateral nasal wall and the turbinates, inhibiting physiological airflow, were removed by the surgery to realize the enlargements of the nasal cavity volumes and to increase the ratio between nasal cavity volume and surface area. However the researches mentioned here dealt with only a few patient-cases even though there are individual differences in the shape of human nasal cavity and in the grade of medical conditions. The past researches considered the individual differences insufficiently. The authors analyzed intranasal transport phenomena for several patient cases and compared each others in the past study (Monya et al. (2009); Yamamoto et al. (2009)). From the results characteristics of airflow and medicinal droplet transportation strongly depend on inflow conditions such as inflow angle, velocity and size of particle even if there are the individual differences for the shape of patient’s nasal cavity. 24