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Stenting as porous media in anatomically accurate geometries. A comparison of models and spatial heterogeneity.
Journal of Biomechanics ( IF 2.4 ) Pub Date : 2020-07-19 , DOI: 10.1016/j.jbiomech.2020.109945
Nicolás Dazeo 1 , Javier Dottori 1 , Gustavo Boroni 1 , Ana Paula Narata 2 , Ignacio Larrabide 1
Affiliation  

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.



中文翻译:

在解剖学上精确的几何结构中作为多孔介质进行支架植入。模型和空间异质性的比较。

在分流器治疗后对颅内动脉瘤血流进行建模已被证明具有重大的科学和临床意义。尚未将CFD用作日常临床工具的原因之一是建立此类仿真所需的时间以及所需的计算时间。这些模拟的加速在治疗计划和设备选择过程中可能会产生相当大的影响。将分流器建模为多孔介质(PM)可以大大改善计算时间。文献中已经提出了许多模型,但是模型之间的定量比较很少。

在本研究中,选择未经治疗的病例,将分流器导流线明确定义为防滑边界条件和五个不同的多孔介质模型进行比较,并对14例不同形状,大小和位置的患者的颅内动脉瘤进行评估。在有限流量条件下,使用有限体积法进行了CFD模拟。评估每个模型的速度,动能,壁切应力和计算时间。然后,使用非参数Kolmogorov–Smirnov检验将所有模型与防滑边界条件进行比较。

性能最低的模型显示的KS统计量的平均值为0.31,偏差为0.2,而具有最佳值的模型始终给出的KS统计量低于0.2。PM模型之间的动能在高估218.3%和低估73.06%之间变化。此外,使用PM模型时,加速比介于4.75倍和5.3倍之间(stdev:0.38倍和0.15倍)。

可以使用PM对分流器进行仿真,并且与标准CFD仿真具有很好的一致性,而FD导线在不到四分之一的时间内都具有无滑移边界条件。在基于几何特性的PM模型上可获得最佳结果,尤其是在使用基于扁平菱形线框方程的异质介质时。

更新日期:2020-08-10
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