Large curvature effect on pulsatile entrance flow in a curved tube: model experiment simulating blood flow in an aortic arch.
We measured the velocity profiles of pulsatile entrance flow in a strongly curved tube using a laser-Doppler anemometer in order to simulate blood flow in the aortic arch under various conditions, i.e., a ratio of tube to curvature radius of 1/3, Womersley parameters of 12 and 18, and peak Dean number up to 1200. Axial isovelocity contours of the cross-section showed the potential vortex to be near the entrance, and with the maximum velocity there being skewed towards the inner wall; thereafter shifting towards the outer wall. During the deceleration phase, reverse axial flow occurred near the inner wall, and a region of this flow extended downstream. The large curvature contributes to the enhancement of the secondary flow and flow reversal, which elevates the wall-shear stress oscillations. The location of elevated wall-shear oscillations corresponds to the vessel wall region where atherosclerotic formation frequently occurs; thereby indicating that both the large curvature and pulsatility play key roles in formation of localized atherosclerotic lesions.
Naruse
T
T
Department of Mechanical Engineering, Keio University, Yokohama, Japan.
Tanishita
K
K
D001013:Aorta, Thoracic / Q000502:physiology*; D001783:Blood Flow Velocity; D006801:Humans; D008955:Models, Cardiovascular; D011673:Pulsatile Flow / Q000502:physiology*; D013314:Stress, Mechanical