Development of fluid-structure interaction simulator and its evaluation by in vitro measurement

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We developed an integrated cardiovascular system simulator and conducted image-based modeling and Fluid-Structure Interaction (FSI) Finite Element analysis (FEA) of human middle cerebral arterial aneurysm (MCAA). The computational model of MCAA is constructed from CT images.1)Development of cardiovascular system simulatorThe fluid is assumed to be laminar, Newtonian, viscous, and incompressible to represent blood. The arterial wall is assumed to be hyperelastic, isotropic, incompressible, and homogeneous. Fluid-structure coupling is performed by strong coupling method.The simulation result suggests that the hydrodynamic force of blood flow on aneurysm wall is not small and FSI analysis should be conducted for accurate analysis of cerebral aneurysm.We also structured peripheral vessel network based on anatomical knowledge, and applied the boundary condition taking account of the effects of peripheral vessel network to 3D hemodynamic simulation. 1D analysis of the peripheral vessels is a … More pplied as the boundary condition for 3D analysis, and 0D model as that for 1D analysis. For 0D model, structured tree impedance model is employed. The peripheral resistance, compliance, and impedance of vessel are treated by 1D analysis and 0D model.As a result, the present method shows a significant difference in flow rate of each artery and improvement in flow distribution and direction. Particularly, for the case with occlusion, collateral flow in the arterial circle of Willis is observed.2)Experiment using in vitro model with realistic vessel geometryWe made the in vitro model using rapid prototyping system and lost model technique. The model has realistic vessel geometry with cerebral aneurysm at bifurcation area. The measurement of flow structure in the aneurysm was conducted under the steady inflow conditions. The streamline is calculated form velocity data, and the flow structure along the aneurysm wall was observed. As the result of calculating the WSS (wall shear stress) using velocity data and geometry data, high WSS area was observed in the aneurysm.3) Comparison between numerical analysis and experimental resultWe compared experimental result to numerical analysis using the vessel geometry of in vitro model at same conditions. The velocity distribution and streamline pattern were similar, but high WSS was appeared at different area. Less