Abstract：
Computational fluid dynamics (CFD) simulations are widely used to develop and analyze blood-contacting medical devices such as left ventricular assist devices (LVADs). This work presents an analysis of the transient behavior of two centrifugal LVADs with different designs: HeartWare VAD and HeartMate3. A scale-resolving methodology is followed through Large Eddy Simulations, which allows for the visualization of turbulent structures. The three-dimensional (3D) LVAD models are coupled to a zero-dimensional (0D) 2-element Windkessel model, which accounts for the vascular resistance and compliance of the arterial system downstream of the device. Furthermore, both continuous- and pulsatile-flow operation modes are analyzed. For the pulsatile conditions, the artificial pulse of HeartMate3 is imposed, leading to a larger variation of performance variables in HeartWare VAD than in HeartMate3. Moreover, CFD results of pulsatile-flow simulations are compared to those obtained by accessing the quasi-steady maps of the pumps. The quasi-steady approach is a predictive tool used to provide a preliminary approximation of the pulsatile evolution of flow rate, pressure head, and power, by only imposing a speed pulse and vascular parameters. This preliminary quasi-steady solution can be useful for deciding the characteristics of the pulsatile speed law before running a transient CFD simulation, as the former entails a significant reduction in computational cost in comparison to the latter.
摘要：
计算流体动力学(CFD)模拟广泛用于开发和分析血液接触医疗设备,例如左心室辅助设备(LVAD)。这项工作对两种具有不同设计的离心LVAD的瞬态行为进行了分析：HeartWareVAD和HeartMate3。通过大涡模拟遵循比例分解方法，这允许湍流结构的可视化。3DLVAD模型耦合到0D2元素Windkessel模型，这说明了设备下游动脉系统的血管阻力和顺应性。此外，分析了连续流和脉动流两种运行模式。对于脉动条件，心脏Mate3的人工脉冲被施加，导致HeartWareVAD中的性能变量比HeartMate3中的变化更大。此外，将脉动流模拟的CFD结果与通过访问泵的准稳态图获得的结果进行比较。准稳态方法是一种预测工具，用于提供流量脉动演化的初步近似值，压头,和权力,通过仅施加速度脉冲和血管参数。这个初步的准稳态解可以用于在运行瞬态CFD模拟之前确定脉动速度定律的特性。与后者相比，前者需要显著降低计算成本。
