Govindarajan V, Udaykumar H S, Chandran K B
Department of Biomedical Engineering, The University of Iowa, Iowa City, IA-52242.
J Mech Med Biol. 2009 Jun 1;9(2):161-176. doi: 10.1142/S0219519409002912.
The flow dynamics through the peripheral and hinge regions of a bi-leaflet mechanical heart valve are complex and result in abnormally high shear stresses particularly during the closing phase of the valve function. It has been observed that, the late stages of closure is more significant in the dynamics of platelet activation; therefore, the later stages of closure is simulated by solving the two-dimensional Navier-Stokes equations using an Eulerian Levelset based sharp interface Cartesian grid method. Using a fixed Cartesian mesh incorporating local mesh refinement for solution accuracy and efficiency, the flow through and within a recessed hinge design and an open pivot hinge design is compared. Platelets are modelled as point particles by Lagrangian particle tracking algorithm with one way coupling. A dilute particle flow is assumed and particle-particle interactions are neglected. It was observed that the hinge region of the open pivot valve indicated a lower potential for activation of platelets compared to that in valves with a recessed hinge design.
双叶机械心脏瓣膜外周和铰链区域的流动动力学很复杂，会导致异常高的剪切应力，尤其是在瓣膜功能的关闭阶段。据观察，关闭后期在血小板激活动力学中更为显著；因此，通过使用基于欧拉水平集的尖锐界面笛卡尔网格方法求解二维纳维-斯托克斯方程来模拟关闭后期。通过采用包含局部网格细化以提高求解精度和效率的固定笛卡尔网格，对通过凹入式铰链设计和开放式枢轴铰链设计的流动以及内部流动进行了比较。血小板通过拉格朗日粒子跟踪算法以单向耦合的方式被建模为点粒子。假设为稀颗粒流，忽略颗粒间相互作用。据观察，与具有凹入式铰链设计的瓣膜相比，开放式枢轴瓣膜的铰链区域显示出较低的血小板激活潜力。
