Flow in an aneurysm model: correlation between numerical simulation and blood platelet deposition

Laminar and turbulent numerical simulations of steady flow in an aneurysm model were carried out over Reynolds numbers ranging from 300 to 3600. The numerical simulations are used to study the fluid dynamic mechanisms that characterize aneurysm deterioration, by correlating them to in vitro blood platelet deposition results. It is shown that the recirculation zone formed inside the aneurysm cavity creates conditions that promote thrombus formation and the viability of rupture. The point of reattachment at the distal end of the aneurysm is characterized by a pronounced wall shear stress peak. As the Reynolds number increases in laminar flow, the center of the recirculation region migrates toward the distal end of the aneurysm, increasing the pressure at the reattachment point. Under fully turbulent flow conditions (Re=3600) the wall shear stress values are almost one order of magnitude larger than those for the laminar cases. Interpretations of the combined results agree with in vivo findings of aneurysm progression, and may be used to surmise the fluid dynamics that play a pivotal role in this progression