Computational fluid–structure analysis of the impact of leaflet thickness and protrusion height on the flutter phenomenon in aortic valve bioprostheses

• Published in: Meccanica (Milan) Vol. 59; no. 5; pp. 685 - 701
• Main Authors: Costa, Matheus Carvalho Barbosa, Gonçalves, Saulo de Freitas, Fleury, João Victor Curado, Silva, Mário Luis Ferreira da, Huebner, Rudolf, Avelar, Artur Henrique de Freitas
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2024; Springer Nature B.V
• Subjects: Aorta; Automotive Engineering; Boundary conditions; Civil Engineering; Classical Mechanics; Engineering; Fluid flow; Fluid-structure interaction; Flutter; Heart valves; Impact analysis; Mechanical Engineering; Mechanical properties; Newtonian fluids; Structural analysis; Thickness; Turbulence intensity; Velocity distribution; Vibration; Bioprosthesis; Fluid–structure interactions; Flutter; Leaflet thickness; Arbitrary Lagrangian Eulerian; Protrusion height
• ISSN: 0025-6455; 1572-9648
• DOI: 10.1007/s11012-024-01809-y

Although it is associated with the low lifetime of aortic valve bioprostheses, flutter has little been studied in the dynamics of these valves. To improve the understanding of flutter in bioprosthetic leaflets, the present work evaluates the effect of leaflet thickness and protrusion height on flutter parameters through the computational fluid–structure interaction. A bioprosthesis geometry, based on a geometric model available in the literature, and a simplified fluid domain were developed. As a boundary condition, a parabolic velocity profile was applied at the inlet, outflow at the outlet, and fixed support at the sides of the leaflets. The valve cusps were considered with linear elastic and isotropic mechanical behavior, while the blood was modeled as a Newtonian fluid. Turbulence was modeled according to the k-
ω
SST model. The numerical results showed that, due to the occurrence of leaflet oscillations, both fluid dynamic quantities, such as pressure, velocity, and turbulence intensity, and solid domain quantities, such as stress and strain, exhibited an irregular and oscillatory behavior. Furthermore, the radial displacements of the leaflets were asynchronous, and the phase difference between the leaflets increased with increasing thickness. The frequencies ranged from 28.3 to 36.7 Hz, while the amplitudes ranged from 5.34 to 6.53 mm, where the valve with the lowest protrusion height did not develop flutter