Obstructive Sleep Apnea (OSA) is a breathing disorder that occurs during sleep. This syndrome affects numerous people, especially those with abnormal body fat composition parameters such as body mass index (BMI) of more than 25 kg/m2 (overweight & obesity). OSA ensues when the tongue and soft palate muscles in a relaxed condition move towards gravity when the patient is in a supine position; this causes narrowing and blockage on the upper airway affecting breathing. There are several treatments for OSA, including upper airway surgery. A better understanding of airflow characteristics will assist ENT surgeons in identifying the blockage area. This paper examines airflow characteristics of the upper airway for overweight sleep apnea patients. The narrow and blockage area on the respiratory tract causes turbulence formation that is evaluated using Computational Fluid Dynamic (CFD) based on an actual parameter of the 3D model obtained by CT scan image result. Reynold’s averaged Navier-Stoke (RANS) equation and turbulent model, k-ω shear stress transport (SST), were applied. Airflow fluctuation was characterized by crucial parameters such as velocity, pressure, and turbulent kinetic energy (TKE). The result shows that the narrow cross-sectional area of the airway causes accretion of the velocity and pressure in the pharyngeal airway. The increasing airflow parameter results in high turbulent kinetic energy (TKE) that will determine the severity level of OSA patients. Investigating airflow characteristics in overweight OSA patients will help the medical practitioner validate the narrow and blockage area for the surgery.

This paper aims to investigate and present the numerical investigation of airflow characteristics using Turbulent Kinetic Energy (TKE) to characterize the upper airway with obstructive sleep apnea (OSA) under inhale and exhale breathing conditions. The importance of TKE under both breathing conditions is that it show an accurate method in expressing the severity of flow in sleep disorder. Computational fluid dynamics simulate the upper airway's airflow via steady-state Reynolds-averaged Navier-Stokes (RANS) with k-ω shear stress transport (SST) turbulence model. The three-dimensional (3D) airway model is created based on the CT scan images of an actual patient, meshed with 1.29 million elements using Materialise Interactive Medical Image Control System (MIMICS) and ANSYS software, respectively. High TKE were noticed around the region after the necking (smaller cross-sectional area) during the inhale and exhale breathing. The turbulent kinetic energy could be used as a valuable measure to identify the severity of OSA. This study is expected to provide a better understanding and clear visualization of the airflow characteristics during the inhale and exhale breathing in the upper airway of patients for medical practitioners in the OSA research field.