Direct numerical simulation of secondary currents in arterial flow with stents

Direct numerical simulations are performed to investigate secondary motions induced by stent-like geometries in laminar and turbulent pipe flow. Three configurations of increasing complexity are considered: straight ridges, helical ridges, and ambihelical ridges. In laminar flow, only weak modifications of the mean velocity are observed, with secondary currents arising mainly from pressure gradients. In contrast, turbulent flow produces strong secondary motions: counter-rotating vortices for straight ridges, and large-scale cross-sectional rotation for the helical case. The skin friction coefficient increases with geometric complexity, with helical ridges yielding the strongest enhancement due to combined pressure-driven and turbulence-induced mechanisms. These results highlight the significant role of stent structures in shaping secondary currents and transport processes.