NUMERICAL MODELING OF FLUID-STRUCTURE INTERACTIONS IN CARDIOVASCULAR MECHANICS

External and physiological loading of the cardiovascular system gives rise to complex mechanical interactions between the fluid(blood) and the solid(extensible vessel wall).  An understanding of such fluid-structure interactions is critical to modeling and rendering the response of the cardiovascular system to these loads.  Recent developments in code coupling techniques, including commercial codes, have generated numerical solution methodologies useful for studying cardiovascular fluid-structure interactions.  This paper presents one approach for such fluid-structure interaction(FSI) problems by utilizing a mesh-based code coupling to ANSYS.  This commercially available finite element code provides two separate fluid and structure solvers with a load-vector coupling.  An iterative algorithm is employed to perform boundary parameter transfer, interface mapping, and remeshing.  The Hagen-Poiseuille and Womersley flows in an elastic vessel are chosen as representative characteristic cardiovascular flows and numerical solutions from the FSI solver are compared to these analytical solutions.  The calculation for the Womersley flow suggest that the velocity profiles for elastic wall conditions change considerably when the inertial force is dominant in the system.  For practical application, the FSI solver is applied to elastic curved vessels with several sets of elastic moduli under a developing flow condition.  The use of a FSI approach in such a conduit results in a significant increase of wall shear stress at the inner wall in the fluid domain and an orientation change of the maximum principal stress in line with the longitudinal direction along the vessel in the structural domain.