Shi Yubing, Zhao Yong, Yeo Tony Joon Hock, Hwang Ned H C
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore.
J Heart Valve Dis. 2003 Mar;12(2):245-55.
Most previous computational fluid dynamics (CFD) studies of blood flow in mechanical heart valves (MHVs) have not efficiently addressed the important features of moving leaflet and blood-leaflet interaction. Herein, computationally efficient approaches were developed to study these features and to obtain better insight into the pulsatile flow field in bileaflet MHVs.
A simple and effective method to track the moving boundary was proposed, and an efficient method for calculating the blood-leaflet interaction applied. In this way, a CFD code was developed to study the pulsatile flow field around bileaflet MHVs. The CFD code was parallelized on a supercomputer to reduce turn-around time in the simulation. The solver was then used to study the opening process in a St. Jude Medical (SJM) size 29 bileaflet MHV.
CFD results showed that, in the opening process, the flow field was consistently partitioned into two side channels and a central channel due to the presence of the two leaflets. In the flow field near the surface of the two leaflets, the fluid velocity followed the local surface velocity of the leaflets, thus showing a strong blood-leaflet interaction effect. Throughout the valve-opening process, peak velocities were always observed near the tips of the valve leaflet. The CFD simulation showed that the opening process took approximately 0.044 s, which compared well with experimental findings.
The new computational approaches were efficient and able to address the moving leaflet and blood-leaflet interaction. The flow field in the opening process of a SJM 29 bileaflet MHV was successfully simulated using the developed solver.
以往大多数关于机械心脏瓣膜（MHV）内血流的计算流体动力学（CFD）研究，都未能有效处理活动瓣叶及血液 - 瓣叶相互作用的重要特征。在此，我们开发了计算效率高的方法来研究这些特征，并更深入地了解双叶型MHV中的脉动流场。
提出了一种简单有效的移动边界跟踪方法，并应用了一种计算血液 - 瓣叶相互作用的高效方法。通过这种方式，开发了一个CFD代码来研究双叶型MHV周围的脉动流场。该CFD代码在超级计算机上进行了并行化处理，以减少模拟中的周转时间。然后使用该求解器研究圣犹达医疗（SJM）29号双叶型MHV的开启过程。
CFD结果表明，在开启过程中，由于两个瓣叶的存在，流场始终被分为两个侧通道和一个中央通道。在两个瓣叶表面附近的流场中，流体速度跟随瓣叶的局部表面速度，从而显示出强烈的血液 - 瓣叶相互作用效应。在整个瓣膜开启过程中，峰值速度始终出现在瓣膜瓣叶尖端附近。CFD模拟显示开启过程耗时约0.044秒，与实验结果吻合良好。
新的计算方法高效且能够处理活动瓣叶及血液 - 瓣叶相互作用。使用开发的求解器成功模拟了SJM 29双叶型MHV开启过程中的流场。
