Knowledge of flow inside the human airway is very important for medical practitioner to make accurate diagnosis. With the presence stenosis inside the airway, the flow will be changed significantly and will directly affect the input to the main bronchi. In this study, patient-specific image is used and remodelled using computational fluid dynamic software to simulate the flow within the trachea. The image contains one stenosis which was then reconstructed to other locations. This procedure will enable the study of flow behaviour in the trachea with different stenosis locations. Emphasis of analysis is focused on the flow and pressure distribution along the main airway. For each model, computations were carried out in three different flow rates which are 15 l/min, 60 l/min and 100 l/min corresponding to regular human activity which are resting, normal and heavy excersice breathing, respectively. The results show as stenosis located at the upper third of the trachea, the pressure drop along the trachea are insignificant in every breathing condition but differ to the velocity where the maximum velocity is increase as the flow rate increase. For stenosis located at the lower third or the trachea, both pressure drop and velocity did effect clearly as the flow rate increase. The effect of different location of the stenosis on the velocity distribution along the centerline shows similar increment in every flow rate and the risk in breathing difficulties if the patient having a stenosis at the third location is three times higher compare to the first location if the patient in resting condition. It increases to five times higher when doing the regular activity and eight times higher if the patient doing heavy exercise. The comparison is based on the same size of the stenosis
