Modeling and simulation of blood flow in a sac-type left ventricular assist device

Left ventricular assist devices (LVADs) are among the most important mechanical artificial hearts in medical equipment industry. Since the need for heart transplantation is on the rise, there is a requirement for implantable LVADs, which can be safely used for long-term purposes. One of the most promising kinds of these devices is the sac-type LVAD (ST-LVAD) that has the ability to generate pulsatile flow. In this study and for the first time, three different models of ST-LVAD are analyzed numerically. In the first model, the motion of the elastic membrane wall is simplified, while in the second model, the motion is assumed to be wavy. The pressure boundary conditions are added to the second model to allocate for the effect of pressure on the flow pattern, and hence, form the third model. The simulation results of the analyzed models show that in this particular type of LVAD, the viscous term of the applied stress from the fluid on the moving wall is negligible, compared with the pressure term. Additionally, it can be concluded that the motion pattern of the moving wall does not affect the blood flow pattern in a great deal. Furthermore, the inclusion of the fluid pressure in the boundary conditions does not have a major influence on the blood flow pattern.