Abstract
This study adopts numerical simulation to discuss the fluid flow inside the stented lateral aneurysm arising from the straight parent vessel. The implicit solver was based on the time-dependent incompressible Navier-Stokes equations of laminar flow. Solutions were generated by a cell-center finite-volume method that used second order upwind and second order center flux difference splitting for the convection and diffusion term, respectively. The second order Crank-Nicolson method was used in the time integration term. To handle the pressure-velocity coupling the SIMPLEC algorithm was adopted. Complementary flow visualization was performed to validate the numerical code. The straight afferent vessel had an inner diameter 10 mm. The diameters of the aneurysmal orifice, neck, and fundus were 14 mm, 10 mm, 15 mm, respectively, and the distance between the orifice and dome measured 20 mm. A 30 mm long helix-shaped stent with four blocking ratios of 0%, 30%, 50%, 75% were examined. The density and dynamic viscosity of working fluid were 1050 kg/m3 and 3.5 cp, respectively. Human volume flow rate waveform of the posterior carotid artery was considered with maximum Reynolds number of 250 and Wormersley number of 3.9. Computational results are presented in terms of the pulsatile main and secondary flow velocity vector fields, inflow velocity (IV) into the aneurysm, and the distributions of wall shear rate (WSR), and wall tension stress. It is found that as the blocking ratio increases, both the IV and WSR decrease exponentially. In general, the hemodynamic flow patterns and parameters examined are found to change favorably for the formation of thrombosis after stenting.