Fluid flow in a helical vessel in presence of a stenosis

Large arteries are not straight and rather present curvature and torsion. The present study analyzed fluid flow in a helical vessel without and with a stenosis in comparison with an analogous rectilinear vessel. The analysis is performed by three-dimensional numerical simulation of the Navier-Stokes equations under steady conditions considering stenosis as an axially symmetric reduction of vessel lumen. Results show that the double curvature gives rise to persistent secondary motion which combines with the vorticity separated behind the constriction to develop a complex three-dimensional vorticity structure. The curved streamlines and the three-dimensional vortex wake result in a increase of energetic losses in helical vessels. However, the same symmetry break due to the double curvature improves the capacity of self-cleaning and allows a more rapid wash-out of the flowing blood.