Numerical transient state analysis of partly obstructed haemodynamics using FSI approach

Blood interacts in compliance with the vessels it flows in, determining effects of fluid-structure interaction (FSI). Using this approach, the present paper analyses the blood flow and its pathological conditions before diagnostic (Doppler catheters) or pathological (stenoses) obstacles. Catheters are concentric cylinders with defined vessels, whereas stenoses are shaped as triangles, trapeziums or hemi-ellipses. Rather than a basic/rigid case, three models were adopted to describe the artery wall dynamics: elastic (Hooke), hyper-elastic Mooney-Rivley 1 (MR1) and hyper-elastic Mooney-Rivley 2 (MR2). Blood has non-Newtonian rheological properties (Casson fluid. The numerical study used the CFD code Comsol Multiphysics, version 3.4. The FSI effect was studied through 3 physical parameters with reference to the blood flow: minimum velocity (re-circulation), maximum velocity (the mechanical stress on the obstacle) and the disturbance length. Results show a strong dependence of the FSI effect on the characteristics of the obstacle considered and on the kind of elastic/hyper-elastic model chosen. In a few cases, however, the results of the old rigid-vessel approach were reasonably accurate.