Numerical simulations of unsteady flows in a stenosed coronary bypass graft
Using finite element method, physiological blood flows through a three-dimensional model of coronary graft are numerically analyzed. The model includes a stenosis shape in the host artery upstream from the anastomosis. Recirculating areas, secondary flows, wall shear stress (wss) and spatial wall shear stress gradients (wssg) are studied for different flow repartitions and at different times in the cycle. The temporal and spatial evolutions of the recirculating areas downstream from the stenosis, their interactions with the flow issued from the graft and their associated wall shear stresses highlight that the presence of the stenosis in the recipient artery is essential to predict the evolution of a grafting at the beginning of its implantation. The areas downstream from the stenosis expansion, non-existent for an host artery without stenosis, are submitted to low and oscillating wss comprized between –0.5N/m2 and 0. The stagnation point on the recipient artery floor is submitted to high positive and negative wssgnd values and its location is dependent on the residual flow through the stenosis.