Fluid-structure interaction (FSI) simulations using a patient-specific geometry are carried out to investigate the influence the length of elastic parent artery and the position of constraints in the solid domain on the accuracy of patient-specific FSI simulations. Three models are tested: Long, Moderate, and Short, based on the length of the elastic parent artery. All three models use same wall thickness (0.5. mm) and the elastic modulus (5. MPa). The maximum mesh displacement is the largest for the Long model (0.491. mm) compared to other models (0.3. mm for Moderate, and 0.132. mm for Short). The differences of hemodynamic and mechanical variables, aneurysm volume and cross-sectional area between three models are all found to be minor. In addition, the Short model takes the least amount of computing time of the three models (11. h compared to 21. h for Long and 19. h for Moderate). The present results indicate that the use of short elastic upstream artery can shorten the time required for patient-specific FSI simulations without impacting the overall accuracy of the results.