Pulsatile non-Newtonian haemodynamics in a 3D bifurcating abdominal aortic aneurysm model

Abstract

Numerical prediction of non-Newtonian blood flow in a 3D abdominal aortic aneurysm bifurcating model is carried out. The non-Newtonian Carreau model is used to characterise the shear thinning behaviour of the human blood. A physical inlet velocity waveform incorporating a radial velocity distribution reasonably representative of a practical case configuration is employed. Case studies subject to both equal and unequal outlet pressures at iliac bifurcations are presented to display convincingly the downstream pressure influences on the flow behaviour within the aneurysm. Simulations indicate that the non-Newtonian aspects of the blood cannot at all be neglected or given a cursory treatment. The wall shear stress (WSS) is found to change significantly at both the proximal and distal ends of the aneurysm. At the peak systole, the WSS is peak around the bifurcation point, whereas the WSS becomes zero in the bifurcation point. Differential downstream pressure fields display significant effects regarding the flow evolution in the iliac arteries, whereas little or no effects are observed directly on the flow details in the aneurysm.

Keywords:

• abdominal aortic aneurysm
• pulsatile
• computational fluid dynamics
• wall shear stress

Acknowledgements

The authors would like to acknowledge the funding from MIMIT (Manchester: Integrating Medicine and Innovative Technology). In addition, the authors are also grateful for the substantial physiological support by Professor J. Walker and Mr. Ferdinand Serracino-Inglott of the Medical School of the University of Manchester.