Pulsatile flow in curved vessels

Three distinct secondary flow patterns are observed in the authors' experimental study. The first one is the known Dean flow, which is a double-circulation pattern. The second and the third patterns, which are discovered for the first time, are the clockwise and counterclockwise single-circulation patterns. The transition from one pattern to another is dependent on the spatial boundary conditions and independent of the temporal boundary conditions. The secondary flow velocity gradient and hence its shear stress is comparable to the axial flow velocity gradient and shear stress in the case of single circulation pattern. For the Dean flow or double-circulation secondary flow pattern, shear stress values are much less than those for the axial flow. This finding has potential pathological consequences.