Modelling of Blood’s Non-Newtonian Behaviour in Patient-Specific Aorto-Coronary Bypass Grafts

Abstract

Abstract. 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 CarreauYasuda 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 CrankNicolson 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.

Invocación de métodos remotos (RMI): una revisión de la literatura

“…Tecnología que permite llamar a un método en una máquina virtual remota y, es fácilmente aplicable a una red informática heterogénea [24].…”

“…Uno de los requisitos cruciales es, poder usarlo para varios tipos de computadoras con varios sistemas operativos instalados. Esto es relativamente fácil con RMI, puesto que está incluida en Java, que es un lenguaje de programación independiente de la plataforma [24]. Los estudios realizados sugieren usar RMI que generen y operen con objetos Java en un sistema Remoto [23].…”

Numerical modelling of steady and unsteady flows of generalized Newtonian fluids

“…For the numerical modelling of the generalized Newtonian fluids flow it is necessary to generalize the mathematical models. In this case the viscosity function µγ is defined by cross model (for more details see [8,14,15])…”