Evaluation of the influence of the nasal cavity in flow simulations of the upper airway of a sleep apnea patient

Computational fluid dynamics can be used to analyze the flow pattern and the anatomical predisposition of the airway collapse in patient-specific simulations of sleep apnea patients. Especially the nasal geometry is a major challenge, because of the complex structures and high calculation effort. Due to this limitations the nasal cavity is often excluded. To investigate the influence of the exclusion of the nasal geometry on the flow in the pharynx, four digital models were created. One, which includes the complete nasal structure, and three simplified models, neglecting the nasal geometry using different cutting planes. Airflow simulations using the k-ε turbulence model are performed with an inlet flow rate of 10 l/min. The results show a good agreement of the average velocities. Deviations of the velocity and pressure values occur particularly in the region of the oropharynx and indicate that the type of simplification has a significant influence on the pressure distribution.