Matsumiya Kazuki, Sugiyama Kazuyasu, Inagaki Natsuko F, Takagi Shu, Ito Taichi
Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan.
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, The University of Osaka, Osaka, Japan.
Int J Numer Method Biomed Eng. 2025 Sep;41(9):e70089. doi: 10.1002/cnm.70089.
The effect of shape and size of embolic agents on embolization phenomena has been discussed clinically for transcatheter arterial chemoembolization (TACE). We numerically discussed the unique embolization behavior of new deformable toroidal microparticles in blood vessels by computational fluid dynamics simulations. We employed an Eulerian-Eulerian (full Eulerian) fluid-structure interaction (FSI) method to analyze the flow and deformation behaviors of a deformable torus in a cylindrical pipe. This method, based on the volume of fluid (VOF) method, is implemented in OpenFOAM and is verified by deformation tests with a visco-hyperelastic material in cavity flow. The torus exhibits multiple steady states depending on initial orientation, position, shear modulus, and the aspect ratio between major and minor radii, and the rotation angles of inclined tori reach approximately 80°. Deformation analysis of cross-sections reveals multiple deformation modes such as bending, rotation, and elongation over time. The equilibrium position of the torus is determined by the balance of various lift forces and becomes complex due to increased rotational diameter from elongation. Additionally, vortex structures and pressure gradients elucidate the mechanism that inclined tori are faster than horizontally oriented tori due to their deformation. Finally, flow tests of different microparticle shapes with the same surface area in a stenotic pipe show that the torus has the lowest pressure drop and flow rate reduction. These quantitative predictions are suggestive and encourage experimental study of toroidal microparticles as novel embolic agents in the future.
对于经导管动脉化疗栓塞术（TACE），栓塞剂的形状和大小对栓塞现象的影响已在临床上进行了讨论。我们通过计算流体动力学模拟，对新型可变形环形微粒在血管中的独特栓塞行为进行了数值讨论。我们采用欧拉-欧拉（全欧拉）流固耦合（FSI）方法来分析圆柱形管道中可变形圆环的流动和变形行为。该方法基于流体体积（VOF）法，在OpenFOAM中实现，并通过在腔流中对粘弹性超材料进行变形测试进行了验证。圆环根据初始方向、位置、剪切模量以及长半径与短半径之间的纵横比呈现出多种稳态，倾斜圆环的旋转角度可达约80°。横截面的变形分析揭示了随着时间推移的多种变形模式，如弯曲、旋转和伸长。圆环的平衡位置由各种升力的平衡决定，并且由于伸长导致旋转直径增加而变得复杂。此外，涡旋结构和压力梯度阐明了倾斜圆环由于其变形而比水平取向圆环更快的机制。最后，在狭窄管道中对具有相同表面积的不同微粒形状进行的流动测试表明，圆环具有最低的压降和流速降低。这些定量预测具有启发性，并鼓励未来对环形微粒作为新型栓塞剂进行实验研究。
