Numerical investigation of the turbulent flow features past different mechanical aortic prostheses

Bilefalet Mechanical Valves (BMVs) are routinely implanted as permanent replacement for dysfunctional or diseased aortic valves. Compared with bioprosthetic valves,BMVs are more durable and insusceptible to tearing and calcification, neverthelessthey provide non-physiological hemodynamics which might lead to platelet activationand mechanical hemolysis. Previous studieshave related the blood damaging to augmented levels of turbulent stress downstreamof BMVs, compared to bioprosthetic devices. In this scenario we investigate two emerging technologies for reducing the detrimental effects of hemodynamics past mechanical prostheses, such as a trileaflet configuration and a bileaflet valve with vortex generators(VGs). The simulations are carried out by means of a second-order accurate, finite difference flow solver with direct immersed boundary forcing. When compared to the baseline design, the trileaflet configurationwas found to produce a flow dominated by the core jet, where mixing effects produce lower turbulent kinetic energy peaks. The presence of VGsprovides additional instabilitiesinducing lower vorticity magnitude in the mixing regions, instead.