Experiment-based numerical simulation of unsteady viscous flow in stenoticcollapsible tubes

A numerical method using generalized finite differences is introduced to so lve a nonlinear axisymmetric model with a free moving boundary to study uns teady viscous flow in collapsible stenotic tubes simulating blood flow in s tenotic carotid arteries. The Navier-Stokes equations are used as the gover ning equations for the fluid. The tube wall is treated as a free moving bou ndary whose elastic properties (the tube law) are determined experimentally using a Polyvinyl Alcohol (PVA) hydrogel artery stenosis model. Longitudin al tension is included in the tube law. Physiologically-relevant pressure c onditions and parameters are used in the simulation. Our results indicate t hat severe stenoses cause cyclic pressure changes between positive and nega tive Values at the throat of the stenosis, cyclic tube compression and expa nsions, and sheer stress changing directions in the region just distal to t he stenosis under unsteady conditions. These critical mechanical conditions may be related to excessive artery fatigue and possible plaque cap rupture . Computational and experimental results are compared and reasonable agreem ent is found. (C) 2001 IMACS. Published by Elsevier Science B.V. All rights reserved.