3D large scale simulation of a stented aortic heart valve
Citation for published version (APA):
Dimakopoulos, I., Bogaerds, A. C. B., Anderson, P. D., Hulsen, M. A., & Baaijens, F. P. T. (2009). 3D large scale simulation of a stented aortic heart valve. Poster session presented at Mate Poster Award 2009 : 14th Annual Poster Contest.
Document status and date: Published: 01/01/2009 Document Version:
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The pressure on top & bottom sides of leaflets forms thin boundary layer
along the fixed
edges (Fig.4),
while on the belly
region it takes
moderate values.
Numerical approximation
New numerical techniques are developed to alleviate reported difficulties [1] associated with the accuracy and the stability of calculations at high Reynolds number in three dimensions:
● open inflow/outflow boundary conditions
● second order time integration scheme with automatic adaptation of the time step
● discontinuous Lagrange multipliers for matching the meshes of leaflets and blood & regions with different
discretizations (typically 106number of unknowns).
3D large scale simulation
of a stented aortic heart valve
Y. Dimakopoulos1, A.C.B. Bogaerds1, P.D. Anderson2, M.A. Hulsen2 and F.P.T. Baaijens1 1Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands 2Department of Mechanical Engineering, Eindhoven University of Technology, The Netherlands
/ Department of Biomedical Engineering
Objective of current work
To develop a new, efficient and robust finite element algorithm for the simulation of AHV, which can be used as:
● design tool for tissue engineering heart valves ● diagnostic tool for clinical applications
Results
A global assessment of the blood-leaflets interaction is given in Fig. 3. The aortic leaflets move in response to blood flow. The opening procedure takes place in a symmetric manner, though the model is fully 3D. The aortic heart valve (AHV)
ensures unidirectional blood flow from the left ventricle to the aorta during the cardiac cycle (Fig. 1), while its proper function is essentially controlled by the
surrounding heamodynamic
environment (HE). Computational fluid dynamics (CFD) permit the Resolution of HE at the
microscale, overcoming some of
the inherent limitations of experimental techniques.
Introduction to the physical problem
Physical model
Blood flows through a 3D stented AHV (Fig. 2) of mean diameter w=24 mm and total length H=4w, due to a time-varying pressure gradient. It also exhibits non-Newtonian behavior that is described with the Carreau-Yasuda
References
[1]. J. De Hart, G.W.M. Peters, P.J.G. Schreurs, F.P.T. Baaijens, J. Biomech. 36 (2003), 103-112. [2]. F.N. van de Vosse, J. de Hart, C.H.G.A. Van Oijen, D. Bessems, T.W.M. Gunther, A. Segal, B.J.B.M. Wolters, J.M.A. Stijnen, F.P.T. Baaijens, J. Engrg. Math. 47 (2003), 335-368.
Fig 2. Schematic drawings of the model of the aortic valve
Fig 1. A human heart and its semilunar valves
Soft Tissue Biomechanics and Engineering
Fig 3. Snapshots from the deformation of the mesh due to the motion of the leaflets during the systolic phase
model [2]. All leaflets are assumed to behave as incompressible neo-Hookean solids with constant density.
Fig 4. Distribution of the pressure on the aortic side of the leaflets during the systolic phase
Max:+1.6 kPa Min: -0.7 kPa Max:+9.8 kPa Min: -2.0 kPa Max:+9.4 kPa Min: -2.9 kPa Max: +8.6 kPa Min: -2.2 kPa Max:+10.8 kPa Min:-2.9 kPa Max:+7.5 kPa Min: -2.4 kPa
Thin boundary layers are also appeared in the velocity & the pressure of blood (Fig. 5) , which now can be accurately resolved.
Conclusions
● A new fully 3D algorithm has been developed for the simulation of the motion of the leaflets of the aortic
valve at nearly physiological conditions (Repeak≈2,000).
● For first time, the true rheological behavior of the blood is taken into consideration.
Fig 5. Distribution of the streamwize (vx), radial (vr), azimuthal (vθ)
velocity components and the pressure of the blood across the outlet of the aortic root (Fig. 2)
Max:0.945 m/s Min: 0 m/s Max: 2.5x10-2m/s Min: -2.2x10-1m/s Max:7.3x10-2m/s Min:-7.6x10-2m/s Max:+ 21.1 kPa Min:+ 20.9 kPa
