Winoto S H, Shah D A, Liu H
Department of Mechanical and Production Engineering, National University of Singapore, Republic of Singapore.
Ann Biomed Eng. 1996 Mar-Apr;24(2):321-7. doi: 10.1007/BF02667358.
In an attempt to better assess the severity of valvular regurgitation, an in-vitro experiment has been conducted to estimate turbulent shear stress levels within free jets issuing from different orifice shapes and sizes by means of hot-wire anemometry. On the basis of the measured mean velocities and the jet profiles, the distributions of the normalized kinematic turbulent shear stress (uv/Um2) were estimated for different jets by using an equation available for self-preserving circular jet. The results indicate that the equation can estimate the distributions of uv/Um2 independent of the orifice shape and Reynolds number of the jet. For the range of Reynolds numbers considered, the estimation of maximum turbulent shear stress inferred from these distributions suggests that the critical shear stress level of approximately 200 N/m2, corresponding to destruction of blood cells, is exceeded for typical blood flow velocity of 5 m/s at the valvular lesion.
为了更好地评估瓣膜反流的严重程度，已进行了一项体外实验，通过热线风速仪估计从不同孔口形状和尺寸喷出的自由射流内的湍流剪切应力水平。根据测得的平均速度和射流剖面，使用适用于自保持圆形射流的方程，估计了不同射流的归一化运动湍流剪切应力（uv/Um2）分布。结果表明，该方程可以独立于射流的孔口形状和雷诺数来估计uv/Um2的分布。对于所考虑的雷诺数范围，从这些分布推断出的最大湍流剪切应力估计表明，对于瓣膜病变处5 m/s的典型血流速度，超过了对应于血细胞破坏的约200 N/m2的临界剪切应力水平。
