Pladema - CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, Buenos Aires, Argentina.
Pladema - CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, Buenos Aires, Argentina.
J Biomech. 2020 Sep 18;110:109945. doi: 10.1016/j.jbiomech.2020.109945. Epub 2020 Jul 19.
Modelling intracranial aneurysm blood flow after flow diverter treatment has proven to be of great scientific and clinical interest. One of the reasons for not having CFD as an everyday clinical tool yet is the time required to set-up such simulations plus the required computational time. The speed-up of these simulations can have a considerable impact during treatment planning and device selection. Modelling flow diverters as a porous medium (PM) can considerably improve the computational time. Many models have been presented in literature, but quantitative comparisons between models are scarce. In this study, the untreated case, the explicit definition of the flow diverter wires as no-slip boundary condition and five different porous medium models were chosen for comparison, and evaluated on intracranial aneurysm of 14 patients with different shapes, sizes, and locations. CFD simulations were made using finite volume method on steady flow conditions. Velocities, kinetic energy, wall shear stress, and computational time were assessed for each model. Then, all models are compared against the no-slip boundary condition using non parametric Kolmogorov-Smirnov test. The model with least performance showed a mean K-S statistic of 0.31 and deviance of 0.2, while the model with best values always gave K-S statistics below 0.2. Kinetic energy between PM models varied between an over estimation of 218.3% and an under estimation of 73.06%. Also, speedups were between 4.75x and 5.3x (stdev: 0.38x and 0.15x) when using PM models. Flow diverters can be simulated with PM with a good agreement to standard CFD simulations were FD wires are represented with no-slip boundary condition in less than a quarter of the time. Best results were obtained on PM models based on geometrical properties, in particular, when using a heterogeneous medium based on equations for flat rhomboidal wire frames.
对血流导向装置治疗后的颅内动脉瘤血流进行建模已被证明具有重要的科学和临床意义。目前尚未将计算流体动力学（CFD）作为常规临床工具的原因之一是设置此类模拟所需的时间以及所需的计算时间。这些模拟的加速可以在治疗计划和器械选择中产生重大影响。将血流导向装置建模为多孔介质（PM）可以大大缩短计算时间。文献中已经提出了许多模型，但模型之间的定量比较很少。在这项研究中，选择了未治疗的病例、将血流导向丝明确定义为无滑移边界条件以及五个不同的多孔介质模型进行比较，并在 14 名具有不同形状、大小和位置的颅内动脉瘤患者中进行了评估。使用有限体积法在稳态流条件下进行 CFD 模拟。对每个模型的速度、动能、壁面剪切应力和计算时间进行了评估。然后，使用非参数 Kolmogorov-Smirnov 检验将所有模型与无滑移边界条件进行比较。性能最差的模型的平均 K-S 统计量为 0.31，偏差为 0.2，而最佳值的模型始终给出 K-S 统计量低于 0.2。PM 模型之间的动能差异在高估 218.3%和低估 73.06%之间。此外，当使用 PM 模型时，加速比在 4.75x 和 5.3x 之间（标准差：0.38x 和 0.15x）。当 FD 丝用无滑移边界条件表示时，血流导向装置可以用 PM 进行模拟，并且与标准 CFD 模拟的吻合度较好，时间不到四分之一。在基于几何特性的 PM 模型中获得了最佳结果，特别是在使用基于扁平菱形丝框架方程的非均匀介质时。
