MODELLING OF BLOOD’S NON-NEWTONIAN BEHAVIOUR IN PATIENT-SPECIFIC AORTO-CORONARY BYPASS GRAFTS

MODELLING OF BLOOD’S NON-NEWTONIAN BEHAVIOUR IN PATIENT-SPECIFIC AORTO-CORONARY BYPASS GRAFTS

Vimmr, J.; Jonásová, A.; Bublík, O.

Full Article:

The patency and overall performance of implanted bypass grafts is closely related to hemodynamics and its influence on vessel remodelling. In this regard, numerical investigation of blood flow in models reconstructed from clinical data may, next to clinical research, provide a valuable insight into the problem of graft failures, which are usually associated with restenosis and/or occlusive intimal hyperplasia. In this study, numerical results of pulsatile non-Newtonian blood flow in three realistic aorto-coronary bypass models are presented and further discussed with emphasis placed on the distribution of wall shear stress (WSS) and oscillatory shear index (OSI). Blood’s shear-thinning behaviour is described by the Carreau- Yasuda model. Assuming all model walls to be impermeable and inelastic, the numerical solution of the mathematical model, which has the form of time-dependent non-linear system of Navier-Stokes (NS) equations, is carried out on the basis of the three-stage fractional step method and cell- centred finite volume method formulated for hybrid unstructured tetrahedral grids. The viscous terms of the NS equations are time discretised implicitly using the Crank- Nicolson scheme. The convective terms are solved explicitly and their computation utilises a local time-stepping technique in order to improve the overall computational efficiency of the developed CFD code.

The patency and overall performance of implanted bypass grafts is closely related to hemodynamics and its influence on vessel remodelling. In this regard, numerical investigation of blood flow in models reconstructed from clinical data may, next to clinical research, provide a valuable insight into the problem of graft failures, which are usually associated with restenosis and/or occlusive intimal hyperplasia. In this study, numerical results of pulsatile non-Newtonian blood flow in three realistic aorto-coronary bypass models are presented and further discussed with emphasis placed on the distribution of wall shear stress (WSS) and oscillatory shear index (OSI). Blood’s shear-thinning behaviour is described by the Carreau- Yasuda model. Assuming all model walls to be impermeable and inelastic, the numerical solution of the mathematical model, which has the form of time-dependent non-linear system of Navier-Stokes (NS) equations, is carried out on the basis of the three-stage fractional step method and cell- centred finite volume method formulated for hybrid unstructured tetrahedral grids. The viscous terms of the NS equations are time discretised implicitly using the Crank- Nicolson scheme. The convective terms are solved explicitly and their computation utilises a local time-stepping technique in order to improve the overall computational efficiency of the developed CFD code.

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DOI: 10.5151/meceng-wccm2012-18501

Referências bibliográficas

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Como citar:

Vimmr, J.; Jonásová, A.; Bublík, O.; "MODELLING OF BLOOD’S NON-NEWTONIAN BEHAVIOUR IN PATIENT-SPECIFIC AORTO-CORONARY BYPASS GRAFTS", p-1634-1653. In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1]. São Paulo: Blucher, 2014.
ISSN 23580828, DOI 10.5151/meceng-wccm2012-18501