Biomedical subjects

Chan Hyun Youn

Publications and source records attributed to Chan Hyun Youn.

3 recordsLinked to original sources

PubMed2004

Computational analysis of the three-dimensional hemodynamics of the blood sac in the twin-pulse life-support system.

Blood flow in the twin-pulse life-support system (T-PLS) pulsatile blood pump was simulated using a three-dimensional rigid body-fluid-solid interaction model. This model can delineate the blood flow in the T-PLS resulting from operation of a moving actuator. The numerical method used in this study was a commercial finite element package called ADINA. We used a contact and fluid-solid interaction model to compute the blood hemodynamics in the sac. Blood flow is generated by the motion of the actuator, which strongly interacts with the solid material surrounding the blood. To obtain basic bioengineering data on the optimum operation of the T-PLS, we simulated four models in which the actuator moved at different speeds and investigated both the flow pattern and the distribution of shear stress. During the contraction phase, a strong axial flow is observed around the outlet, whereas there is stagnant flow around the inlet. The maximum shear stress in each model depends on the operation mode; however, all four models have similar flow rates. The sinusoidal mode exhibited the lowest maximum shear stress and is thus considered the most efficient of the four operating modes.

Blood Flow Velocity↗

PubMed2004

Mathematical modeling of cardiovascular system dynamics using a lumped parameter method.

This work reviews the main aspects of cardiovascular system dynamics with an emphasis on modeling hemodynamic characteristics by the use of a lumped parameter approach. The methodological and physiological aspects of the circulation dynamics are summarized with the help of existing mathematical models. The main characteristics of the hemodynamic elements, such as the heart and arterial and venous systems, are first described. Distributed models of an arterial network are introduced, and their characteristics are compared with those of lumped parameter models. We also discuss the nonlinear characteristics of the pressure-volume relationship in veins. Then the control pathways that participate in feedback mechanisms (baroreceptors and cardiopulmonary receptors) are described to explain the interaction between hemodynamics and autonomic nerve control in the circulation. Based on a set-point model, the computational aspects of reflex control are explained.

Animals↗

PubMed2003

Numerical analysis of the three-dimensional blood flow in the korean artificial heart.

Flow in the blood sac of the Korean artificial heart is numerically simulated by finite element method. Fluid-structure interaction algorithm is employed to compute the three-dimensional blood flow interacting with the sac material. For verification of the numerical method of fluid-structure interaction, two-dimensional flow in a collapsible channel with initial tension is simulated and the results are compared with numerical solutions from the literature. Incompressible viscous flow and linear elastic solid are assumed for the blood and the sac material in the device, respectively. The motion of the actuator is simplified by a time-varying pressure boundary condition imposed on the outer surface of the sac. Numerical solutions on the unsteady three-dimensional blood flow in the sac are provided for the cactus-type model in this study. During systole, the inlet is closed and the blood sac is squeezed by the action of the prescribed pressure on the surface. During diastole, the sac is filled with the blood coming from the inlet while the outlet is closed. A strong flow to the outlet and a stagnated flow near the inlet are observed during systole. Shear stress distribution is also delineated to assess the possibility of thrombus formation. We also simulate numerically the hemodynamics of "the reversed model" where the inlet and outlet are reversed for surgical convenience. It is observed that a recirculating flow was generated near the inner corner of the sac in the reversed model. To assess the material strength of the sac, the shear stress distribution in the solid material is also presented.

Algorithms↗