Unsteady flow in a rigid 3-D model of the carotid artery bifurcation.

In the present study, finite element calculations are performed of blood flow in the carotid artery bifurcation under physiological flow conditions. The numerical results are compared in detail with laser-Doppler velocity measurements carried out in a perspex model. It may be concluded that the numerical model as presented here is well capable in predicting axial and secondary flow of incompressible Newtonian fluids in rigid-walled three-dimensional geometries. With regard to the flow phenomena occurring, a large region with reversed axial flow is found in the carotid sinus opposite to the flow divider. This region starts to grow at peak systole, has its maximal shape at minimal flow rate and totally disappears at the start of the acceleration phase. C-shaped axial velocity contours are formed in the deceleration phase, which are highly influenced by secondary flows. These latter flows are mainly induced by centrifugal forces, flow branching, and tapering of the carotid sinus. Lowering the sinus angle, the angle between the main branch and the carotid sinus, results in a smaller region with reversed axial flow.