Model experiment on physiologically intermittent flow in an aortic arch

The aortic blood flow is characterized by the intermittent entry flow in a strongly curved tube because of the presence of stationary diastolic period. In this study we measured the axial and secondary velocity of intermittent flow in a strongly curved tube simulating the blood flow in an aortic arch (the ratio of the tube radius to the radius of curvature=1/3, Dean number=791) by Laser Doppler Velocimeter. In order to reveal the effect of diastolic period (t(d)) on the flow development, t(d) ranges from 0.4 to 2.0 sec, whereas the systolic period remains constant (0.4 sec). During the deceleration phase of the systolic period, reversed axial flow starts to appear near the inner wall. This reversed axial flow becomes significant at the end of systolic phase and causes to induce the new secondary flow development. For t(d)=0.4 sec flow does not diminish completely until the end of the diastolic period and affects the flow development in the following systolic period. This secondary flow augmentation in the beginning of diastolic phase is remarkable in the entry region of curved tube.