Sensitivity and downstream influence of the impinging leading-edge vortex instability in a bileaflet mechanical heart valve

Bileaflet mechanical heart valves (BMHV) create unphysiological turbulent flow. Such flow involves multiple instability mechanisms interacting with one another in a confined geometry. For instance, an impinging leading-edge vortex (ILEV) creates disturbances at the leading edge of valve leaflets, while potentially promoting turbulence downstream BMHV (Zolfaghari and Obrist, Phys. Rev. Fluids , vol. 4, 2019). In this article, we use adjoint-based methods to study structural sensitivity ILEV BMHV, quantify role maximum disturbance energy growth wake BMHV. We first present direct numerical simulation show effect on valve. Second, perform modal linear stability analysis two-dimensional subdomain attached leaflet. investigate global modes associated using their adjoints, then passive control scenario local feedback source. This results partial improvement oscillations leaflets. finally non-modal approach identify optimal initial conditions for achieving arbitrary locations. that, sufficiently large times, condition highest points edge, which includes instability. Our illustrates that improved shape can effectively reduce