集中系モデルによる血管内脈波の解析

概要

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A waveform of a pulse wave in a blood vessel often changes because of nonlinear effect. To analyze this nonlinear phenomenon, the finite difference method has been used. However, the treatment of the method is cumbersome. In order to overcome this problem, we propose a concentrated mass model to analyze the nonlinear pulse wave problems. This model consists of masses, connecting nonlinear springs, connecting dampers, base support dampers, and base support springs. The characteristic of connecting nonlinear spring is derived from the relationship between pressure and diameter of a blood vessel, and the base support damper and the base support spring are derived from the shear stress from a wall of a blood vessel. The pulse waves in the blood vessel of the dog measured by Laszt are analyzed numerically by using the proposed model in order to confirm the validity of the model. Numerical computational results agree very well with the experimental results. Especially, "steepening phenomenon" generated by the nonlinear effect of fluid is numerically reproduced. Therefore, it is concluded that the proposed model is valid for the numerical analysis of nonlinear pulse wave problem.