BACKGROUND:Recirculation zones within the blood vessels are known to influence the initiation and progression of atherosclerotic lesions. Quantification of recirculation parameters with accuracy remains subjective due to uncertainties in measurement of velocity and derived wall shear stress (WSS).OBJECTIVE:The primary aim is to determine recirculation height and length from PIV experiments while validating with two different numerical methods: finite-element (FE) and -volume (FV). Secondary aim is to analyze how FE and FV compare within themselves. METHODS:PIV measurements were performed to obtain velocity profiles at eight cross sections downstream of stenosis at flow rate of 200 ml/min. WSS was obtained by linear/quadratic interpolation of experimental velocity measurements close to wall. RESULTS:Recirculation length obtained from PIV technique was 1.47 cm and was within 2.2% of previously reported in-vitro measurements. Derived recirculation length from PIV agreed within 6.8% and 8.2% of the FE and FV calculations, respectively. For lower shear rate, linear interpolation with five data points results in least error. For higher shear rate either higher order (quadratic) interpolation with five data points or lower order (linear) with lesser (three) data points leads to better results. CONCLUSION:Accuracy of the recirculation parameters is dependent on number of near wall PIV data points and the type of interpolation algorithm used.

中文翻译：

---

近壁 PIV 数据对患者特异性中度狭窄患者再循环血流动力学的影响：实验数值比较

背景：已知血管内的再循环区会影响动脉粥样硬化病变的发生和进展。由于速度和派生壁面剪切应力 (WSS) 的测量存在不确定性，因此准确量化再循环参数仍然是主观的。 目标：主要目的是通过 PIV 实验确定再循环高度和长度，同时使用两种不同的数值方法进行验证：有限元(FE) 和 -体积 (FV)。次要目的是分析 FE 和 FV 之间的比较。方法：进行 PIV 测量以获得流速为 200 ml/min 的狭窄下游八个横截面的速度分布。WSS 是通过接近壁面的实验速度测量的线性/二次插值获得的。结果：从 PIV 技术获得的再循环长度为 1.47 厘米，与之前报道的体外测量值相差在 2.2% 以内。从 PIV 推导出的再循环长度分别在 FE 和 FV 计算的 6.8% 和 8.2% 内一致。对于较低的剪切速率，具有五个数据点的线性插值会导致误差最小。对于更高的剪切速率，具有五个数据点的高阶（二次）插值或具有较少（三个）数据点的低阶（线性）插值会导致更好的结果。结论：再循环参数的准确性取决于近壁 PIV 数据点的数量和所使用的插值算法类型。具有五个数据点的线性插值导致误差最小。对于更高的剪切速率，具有五个数据点的高阶（二次）插值或具有较少（三个）数据点的低阶（线性）插值会导致更好的结果。结论：再循环参数的准确性取决于近壁 PIV 数据点的数量和所使用的插值算法类型。具有五个数据点的线性插值导致误差最小。对于更高的剪切速率，具有五个数据点的高阶（二次）插值或具有较少（三个）数据点的低阶（线性）插值会导致更好的结果。结论：再循环参数的准确性取决于近壁 PIV 数据点的数量和所使用的插值算法类型。