Velocity distribution and particle deposition in a baboon nose cast

An experimental study has been conducted to investigate the velocity distribution, particle deposition and morphometrical structure in the nasopharyngeal airways of an adult male baboon.;Solid silicone rubber casts of the nasopharyngeal and laryngeal regions of a baboon were made and cross sectional areas were measured in details. It has been shown that the cross sectional area increases from the tip to the midway in the nose. There is a relatively sudden drop in cross sectional area about halfway through the nose. Cross sectional areas of other species reported in published literature are used for comparison. The present study suggests a functional relationship between nasal structure and cross sectional area across species.;A clear acrylic, hollow cast of a baboon nose was made and thermistor probes were inserted to record air velocity in the cast lumen using a wind tunnel to propel air through the cast. The flow travelled from tip of the nose to trachea representing the inspiratory flow and the direction of the flow was reversed for expiratory flow. The flow was determined to be mainly laminar, however areas of turbulence could be detected. The change of flow rates did not have any significant effect on the velocity distribution. The similarities in velocity profiles of baboon nose to those of the human reported in published literature suggests that baboon can be used as a surrogate model for human in airflow studies.;Hollow, flexible nose models were used for deposition studies. The nose models were exposed to monodisperse particles of different sizes for both inspiratory and expiratory flow in an exposure chamber. The particle residence time and nose anatomy were observed to be the main parameters influencing the nasal regional deposition. The same deposition pattern for all particle sizes was noticed and empirical equations relating the fractional deposition to the distance along the nose were obtained.