Numerical Analysis of Physiological Flow in a Curved Tube : Model of an Aortic Arch Flow

Human aortic arch flow was regarded as an intermittent flow in a curved tube with large curvature ratio δ=1/3. The waveform of aortic flow was obtained by means of Doppler echocardiography from both resting and post-exercise conditions of healthy human adults (age : 22∼27). The result in the resting condition (Re=2300, α=13.34) shows that the transverse flow field is characterized by the appearance of three vertices (residue vortex from the previous cycle, one generated near the Stokes layer, and one induced by development of axial velocity boundary layer in the systole). In the post-exercise condition (Re=3400, α=16.7), a Lyne vortex appears in the end of systolic period and exists until the beginning of systolic phase, together with the vertices generated in the diastolic phase. Furthermore multiple period solutions were found numerically for several flow conditions. Our calculation indicates the aortic flow may have multiple period solutions, but its physiological significance is not yet clear.