In the present work we study the fluid - structure interaction in a weakened basilar artery crossed by blood flow. In particular, the aim of this paper is to study the effects of the weakening of the arterial wall on the hydrodynamic pressure and on the shear stress of the wall, whose time and space changes are thought to be one of the causes of aneurysm growth. The solid domain, in its original, natural shape, is cylindrical. The material is modeled as hyperelastic, in particular the Fung's energy model is adopted, and the weakening is modeled through a local axis-symmetric reduction of the main elastic modulus. The fluid domain is studied exploiting a recent approach proposed by Luchini & Charru for quasi-one dimensional flows in slowly varying ducts. This approach allows to write the averaged equations of mass and energy balance, approximated to the first order, on the basis of the velocity profile in a straight duct. The unknowns of the reduced, 1d, coupled problem are the wall pressure, the average velocity, and the wall radial displacement. The problem is solved in two parts: first, considering a suitable time average of the flow, the stationary non-linear coupled problem is solved and the corresponding reference configuration is obtained. Then, we study the variation of the basic unknowns, considering time dependence over the cardiac cycles. The problem is linearized about the reference configuration, the linearized equations are solved as a time-dependent problem. The results we obtain, suggest that, with a 10 % reduction of the main elastic modulus, the shear stress in the weakened zone changes its sign and reaches levels that double the stress value detected in the healthy zone.
|Titolo:||Fluid-structure interaction in a weakened basilar artery|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||4.1 Contributi in Atti di convegno|