Meyer R S, Deutsch S, Maymir J C, Geselowitz D B, Tarbell J M
Department of mechanical Engineering, Pennsylvania State University, University Park 16802-4400, USA.
Ann Biomed Eng. 1997 Nov-Dec;25(6):1081-91.
Three-dimensional laser Doppler velocimetry measurements were acquired in a mock-circulatory loop proximal to a Björk-Shiley monostrut valve in the mitral position, and synchronous ensemble-averaging was applied to form an "average" beat. Two axial locations in the regurgitant flow region of the valve (in the minor orifice) were mapped, and maximum Reynolds shear stresses were calculated. A large spike in regurgitant flow was noted at the beginning of systole, which may be the squeeze flow phenomenon computed by other researchers. A region of sustained regurgitant flow 50 msec later was the focus of this study. Maximum velocities of approximately 3.7 mps were noted, and maximum Reynolds shear stresses of approximately 10,000 dyne/cm2 were calculated. Comparisons were made of two-dimensional (ignoring tangential component) versus three-dimensional shear stresses, and, in this case, in regions of high stress, the differences were insignificant. This suggests that the tangential component of velocity can probably be ignored in similar measurements where the tangential velocity is likely to be small.
在二尖瓣位置的 Björk-Shiley 单支柱瓣膜近端的模拟循环回路中进行了三维激光多普勒测速测量，并应用同步总体平均法形成一个“平均”搏动。对瓣膜反流区域（小瓣口处）的两个轴向位置进行了测绘，并计算了最大雷诺切应力。在收缩期开始时观察到反流流量出现一个大峰值，这可能就是其他研究人员计算出的挤压流现象。本研究的重点是 50 毫秒后持续反流的区域。记录到最大速度约为 3.7 米/秒，并计算出最大雷诺切应力约为 10000 达因/平方厘米。对二维（忽略切向分量）和三维切应力进行了比较，在这种情况下，在高应力区域，差异不显著。这表明在切向速度可能较小的类似测量中，速度的切向分量可能可以忽略。
