Modeling micro-particle deposition in human upper respiratory tract under steady inhalation

Abstract

A representative human upper respiratory tract (URT) with idealized oral region and asymmetric tracheobronchial (TB) airway has been modeled, and laminar-to-turbulent airflow for typical inhalation modes as well as micro-particle transport and deposition has been simulated using CFX10.0 software from Ansys Inc. on a personal computer. The asymmetric TB airway could not be replaced by an extended straight tube as outlet of the oral region while investigating the tracheal airflow field and particle deposition. Compared to an idealized oral airway with an extended straight tube, several differences could be noted: (i) The laryngeal jet extends further down the trachea and inclines towards the anterior wall; (ii) the turbulence level in trachea is less and decays more quickly; (iii) three recirculation zones are visible with intense adverse current after the glottis; (iv) deposition of small particles in trachea is reduced due to lower turbulence. Refined unstructured mesh with densified boundary layer mesh could be a proper substitute for the structured mesh in the human URT model with asymmetric TB airway. Based on the refined unstructured mesh, the physiological structure of uvula in the soft palate is properly simulated in the present human URT model.