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Session: The heart
Session starts: Thursday 24 January, 10:30
Presentation starts: 10:30
Room: Lecture room 559

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Fei Xu (TU Delft)
Sasa Kenjeres (TU Delft)

Abstract:
The aortic root is the region which connects the left ventricle to the ascending aorta. It is the main artery which delivers oxygenated blood to the rest of the body. The current work aims at providing a credible and cost-effective finite-volume based numerical simulations of the flow patterns and pressure within an aortic root model with the bi-leaflet mechanical valve in realistic conditions. At the first stage, the dynamics of the bi-leaflet is simulated as a result of the fluid-structure interaction (FSI) in which leaflets are considered as solid moving objects with a limited degree of freedom. The chimera overset grid technique has been applied for the dynamic meshing. Such method has the main advantage of maintaining a high mesh quality and near-wall-refinement during the simulation. At the second stage, after applying the kinematics of the leaflets from the first stage, different numerical models have been applied: RANS, DES, LES and quasi-DNS. At the second stage, dynamic mesh smoothing and remeshing technique has been used for the simulations since it proved to be considerably more time efficient (approximately 10 times) compared to the overset grid method. The numerically calculated streamwise velocity at two locations and five characteristic time instants over a heartbeat cycle have been compared with available PIV measurements. Obtained results are in a good agreement with experimental data. Furthermore, the vorticity as well as the velocity contours have been compared between different simulations at the central vertical plane. Additionally, energy spectra of the velocity time sequences at five monitoring locations have been analyzed to identify the turbulent/laminar regions in the flow field. The result provided a detailed insights into energetics of the instantaneous flow features of the aortic root model with realistic conditions.