Noguchi Hiroshi, Gompper Gerhard
Institut für Festkörperforschung, Forschungszentrum Jülich, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Jul;72(1 Pt 1):011901. doi: 10.1103/PhysRevE.72.011901. Epub 2005 Jul 1.
The dynamical behavior of vesicles is investigated in simple shear flow. A simulation technique is presented that combines a three-dimensional particle-based mesoscopic model (multiparticle collision dynamics) for the solvent with a dynamically triangulated surface model for the membrane. In this model, thermal fluctuations of the solvent and of the membrane are consistently taken into account. The membrane viscosity can be varied by changing the bond-flip rate of the dynamically triangulated surface. Vesicles are found to transit from steady tank-treading to unsteady tumbling motion with increasing membrane viscosity. At small reduced volumes, the shear induces a transformation from a discocyte to a prolate shape at low membrane viscosity. On the other hand, at high membrane viscosity, the shear induces a transformation from prolate to discocyte, or tumbling motion accompanied by shape oscillations between these two states. Thermal fluctuations induce intermittent tumbling and smooth out the transitions. This effect can be understood from a simplified stochastic model.
研究了简单剪切流中囊泡的动力学行为。提出了一种模拟技术，该技术将用于溶剂的基于三维粒子的介观模型（多粒子碰撞动力学）与用于膜的动态三角剖分表面模型相结合。在该模型中，溶剂和膜的热涨落被一致地考虑在内。膜粘度可通过改变动态三角剖分表面的键翻转速率来改变。发现随着膜粘度的增加，囊泡从稳定的平动转变为不稳定的翻滚运动。在小的折合体积下，剪切在低膜粘度时诱导从盘状细胞到长形的转变。另一方面，在高膜粘度时，剪切诱导从长形到盘状细胞的转变，或伴随着这两种状态之间形状振荡的翻滚运动。热涨落诱导间歇性翻滚并使转变变得平滑。这种效应可以从一个简化的随机模型中理解。
