论文标题
涡流中囊泡的横流迁移
Cross-stream migration of a vesicle in vortical flows
论文作者
论文摘要
我们使用数值模拟在没有惯性力的情况下系统地研究二维（2D）Taylor-Green涡流流中的囊泡动力学。囊泡是封装不可压缩液的高度可变形的膜，它们是红细胞等生物细胞的数值和实验代理。囊泡动力学已在自由空间/有限的剪切，Poiseuille和Taylor-Couette流中进行了研究。泰勒绿色的涡流具有比不均匀流动线曲率，剪切梯度等流动更复杂的特性。我们研究了两个参数对囊泡动力学的影响：内部流体粘度与外部粘度的比率以及囊泡上的剪切力与膜刚度的比率（以毛细管数为特征）。囊泡的变形性非线性取决于这些参数。尽管这项研究为2D，但我们的发现有助于广泛的吸引人的囊泡动力学：如果足够变形，囊泡向内迁移，最终在涡旋中心旋转。如果不是这样，他们将从涡流中心迁移，并穿过周期性的涡流阵列。
We use numerical simulations to systematically investigate the vesicle dynamics in two-dimensional (2D) Taylor-Green vortex flow in the absence of inertial forces. Vesicles are highly deformable membranes encapsulating an incompressible fluid and they serve as numerical and experimental proxies for biological cells such as red blood cells. Vesicle dynamics has been studied in free-space/bounded shear, Poiseuille and Taylor-Couette flows in 2D and 3D. Taylor-Green vortex are characterized with even more complicated properties than those flows such as non-uniform flow line curvature, shear gradient. We study the effects of two parameters on the vesicle dynamics: the ratio of the interior fluid viscosity to that of the exterior one and the ratio of the shear forces on the vesicle to the membrane stiffness (characterized by the capillary number). Vesicle deformability nonlinearly depends on these parameters. Although the study is in 2D, our findings contribute to the wide spectrum of intriguing vesicle dynamics: vesicles migrate inwards and eventually rotate at the vortex center if they are sufficiently deformable. If not so, they migrate away from the vortex center and travel across the periodic arrays of vortices.
