曲がり管内間欠流の数値解析

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Fully developed flow in strongly curved tubes was numerically solved by SIMPLER method. The physiological flow condition was performed by systolic period with sinusoidal volumetric flow rate and following diastolic period. Numerical calculation was carried out under the following conditions, Dean number x=393, frequency parameter a=4〜27, curvature ratio δ=1/2, 1/3 and 1/7, and intermittent parameter η=0〜1/2, where η is the ratio of a systolic time to a whole period. Blood flow is generally characterized by intermittent flow having diastolic period, but the flow does not diminish completely during the diastolic period and retains some strength until the starting phase of the next systolic period. However, the axial flow profiles in systolic period become close to the typical profiles appearing in oscillatory flow with high a. The secondary flow is strongly affected by the conditions at the starting phase, so η plays a major role in the resulting vortex pattern. During the systolic period, the axial and secondary flows gradually decrease as a whole. In detail, reverse axial flow appears in the circumferential region of the tube at the entering phase of the systolic period as behavior of stop flow, and at the same time the development of a boundary layer restarts in this region. This process induces the secondary flow. In the case of small η, the secondary flow forms an additional vortex near the inner corner, while in the case of large η, vortex formation is not seen but the strength of secondary flow increases locally. The strength of the flow does not decrease monotonously. Aortic arch flow strongly depends on the flow from the precycle. The intermittent flow in a curved tube is strongly affected by the flow in the stationary diastolic period.
一般社団法人日本機械学会の論文
1992-08-25

曲がり管内間欠流の数値解析

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