Читать книгу Computational Modeling and Simulation Examples in Bioengineering - Группа авторов - Страница 32

Here, an aneurysm of the straight aorta with deformable walls is modeled according to the FSI algorithm. Blood flow is calculated using 2112 eight‐node 3D elements, and 264 four‐node shell elements used to model the aorta wall, with the wall thickness δ = 0.2 cm. The material constants for blood as in the previous example, while data for the vessel wall are: Young's modulus E = 2.7 MPa, Poisson's ratio v = 0.45, wall thickness δ = 0.2 cm, and tissue density ρ = 1.1 g/cm³. Boundary conditions for the model are prescribed velocity profile (see Figure 1.8a) and output pressure profile as given in Figure 1.8b.

Figure 1.8 Input velocity and output pressure profiles for the AAA on a straight vessel. Inlet peak systolic flow is at t = 0.305 s and outlet peak systolic pressure is at t = 0.4 s. (a) Velocity waveform; (b) pressure waveform.

Source: Modified from Scotti et al. [44].

The results for velocity magnitude distribution at t = 0.305 s are shown in Figure 1.9a. The von Mises wall stress distributions at t = 0.4 s is given in Figure 1.9b. It can be seen that the velocities are low in the domain of the aneurism, while the larger values of the wall stress are at the proximal and distal aneurism zones.

Figure 1.9 Velocity magnitude field and von Mises wall stress distribution for symmetric AAA on the straight vessel. (a) Velocity field distribution for peak at t = 0.305 s; (b) von Mises wall stress distributions for blood pressure peak at t = 0.4 s.