Tesi di LAUREA SPECIALISTICA Titolo Flow Dynamics through a Stenosed Vessel Data 2009-07-21 Autore/i Storti, Francesca Relatore Dubini, G. Full text non disponibile Abstract Arterial stenosis represents one of the most widespread diseases in western countries: severe stenosis leads to stroke or infarction, which are considered one of the major causes of disability and death. Measurements of the blood flow in a stenosed vessel show some practical difficulties, thus numerical simulations of the blood flow field could be of great help for hemodynamic studies related to this disease. Detailed flow patterns can be obtained noninvasively solving the Navier-Stokes equations in order to find velocity and pressure distributions. We have computed the flow field in a stenosed vessel in case of transitional regime, considering two different numerical methods. The stenosed vessel was modelled as a twodimensional channel with a smooth and symmetric constriction. Changing the Reynolds number, both laminar and transitional regimes were simulated and all results were compared to the incompressible flow through a channel with an expansion. If the Reynolds number was sufficiently low, the flow was unique, stable and symmetric. If the Reynolds number was high enough (beyond Re approx 300), the symmetric solution became asymmetric through a Coanda-type wall attachment and a supercritical pitchfork bifurcation. In the end, three different solutions existed: one unstable and symmetric and two stable and asymmetric. Two methods were taken into account: a Navier-Stokes solver with Taylor-Hood elements and a pressure correction method in rotational form. The first method was used to compute the flow field in the stenosed channel; it was implemented using the finite element method with bi-quadratic elements for the velocity and bi-linear elements for the pressure. The pressure correction scheme was implemented for the time-dependent Stokes part and validated using the lid driven cavity flow test case; it was implemented using bi-quadratic finite elements for both physical variables. Implementation of the full set of Navier-Stokes equations with the pressure correction scheme requires future work.