On the choice of outlet boundary conditions for patient-specific analysis of aortic flow using computational fluid dynamics

• Published in: Journal of biomechanics Vol. 60; pp. 15 - 21
• Main Authors: Pirola, S, Cheng, Z, Jarral, O.A, O'Regan, D.P, Pepper, J.R, Athanasiou, T, Xu, X.Y
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 26-07-2017; Elsevier Limited
• Subjects: Aorta; Aorta - physiopathology; Arterial Pressure; Arteries; Biomechanical Phenomena; Blood; Blood flow; Blood Flow Velocity; Boundary conditions; Computational fluid dynamics; Computational fluid dynamics (CFD); Computer applications; Computer Simulation; Fluid dynamics; Fluid flow; Hemodynamics; Hemodynamics - physiology; Humans; Hydrodynamics; Magnetic Resonance Imaging; Mathematical models; Mechanical stimuli; Models, Cardiovascular; NMR; Nuclear magnetic resonance; Outlets; Patient-specific simulation; Personal computers; Physical Medicine and Rehabilitation; Pressure; Regional Blood Flow; Shear stress; Simulation; Veins & arteries; Velocity; Waveforms; Windkessel model; patient-specific simulation; aorta; Windkessel model; boundary conditions; hemodynamics; Computational fluid dynamics (CFD); Patient-specific simulation; Boundary conditions; Aorta; Hemodynamics
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2017.06.005

Abstract Boundary conditions (BCs) are an essential part in computational fluid dynamics (CFD) simulations of blood flow in large arteries. Although several studies have investigated the influence of BCs on predicted flow patterns and hemodynamic wall parameters in various arterial models, there is a lack of comprehensive assessment of outlet BCs for patient-specific analysis of aortic flow. In this study, five different sets of outlet BCs were tested and compared using a subject-specific model of a normal aorta. Phase-contrast magnetic resonance imaging (PC-MRI) was performed on the same subject and velocity profiles extracted from the in vivo measurements were used as the inlet boundary condition. Computational results obtained with different outlet BCs were assessed in terms of their agreement with the PC-MRI velocity data and key hemodynamic parameters, such as pressure and flow waveforms and wall shear stress related indices. Our results showed that the best overall performance was achieved by using a well-tuned three-element Windkessel model at all model outlets, which not only gave a good agreement with in vivo flow data, but also produced physiological pressure waveforms and values. On the other hand, opening outlet BCs with zero pressure at multiple outlets failed to reproduce any physiologically relevant flow and pressure features.