Physiological pulsatile flow experiments in a model of the human aortic arch.

An experimental investigation of physiologically relevant pulsatile flow in a model of the human aortic arch has been conducted. The model aortic arch flow chamber was fabricated in clear acrylic from an in situ casting of the human aorta and was incorporated in a mock-circulatory system. The model excluded the coronary sinuses and the three major branching arteries of the mid-arch region in order to concentrate only upon the effects of the multi-dimensional curvatures and tapering in the aorta. Furthermore, a flow straightening section was placed upstream to the flow chamber to eliminate any fluid disturbances created by the prosthetic aortic valve used in these studies. The qualitative flow visualization studies in the model aorta revealed the presence of strong secondary fluid motions near the inner wall. These helical flows dissipated during diastole, being greatly affected by the dramatic flow reversals which occurred along the inner wall at the onset of diastole. Quantitative studies were conducted using a three-sensor hot-film velocity probe to determine the axial, radial and tangential velocity components at various cross-sections in the aorta. The results showed rapid reversal of axial velocity near the inner wall at the onset of diastole.