Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid
Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid
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含有高粘性流体的可压缩双层囊泡的弛豫动力学
DOI：
10.1103/physreve.94.062414
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发表时间：
2016
影响因子：
2.4
通讯作者：
and Shigeyuki Komura
中科院分区：
文献类型：
--
作者：
T. V. Sachin Krishnan;Ryuichi Okamoto;and Shigeyuki Komura
我们研究了可压缩双层囊泡的松弛动力学与不对称的内部和外部流体介质的粘度。首先，我们探讨了囊泡自由能的稳定性，其中包括膜曲率和两个单层之间的局部密度差之间的耦合。确定了两种类型的不稳定性：小波长不稳定性和较大的波长不稳定性。考虑到体相流体的粘度和单层间摩擦作为耗散源，我们接下来采用Onsager的变分原理推导出的耦合方程的膜和体相流体。由于囊泡的双层结构和球形结构，三种弛豫模式相互耦合。最重要的是，囊泡内较高的流体粘度将弯曲和滑动之间的交叉模式转变为较大的值。当囊泡参数接近不稳定区域时，弛豫动力学显著减慢，相应的模式结构发生显著变化。在某些极限情况下，我们的一般结果减少到以前得到的弛豫率。
We study the relaxation dynamics of a compressible bilayer vesicle with an asymmetry in the viscosity of the inner and outer fluid medium. First we explore the stability of the vesicle free energy which includes a coupling between the membrane curvature and the local density difference between the two monolayers. Two types of instabilities are identified: a small wavelength instability and a larger wavelength instability. Considering the bulk fluid viscosity and the inter-monolayer friction as the dissipation sources, we next employ Onsager's variational principle to derive the coupled equations both for the membrane and the bulk fluid. The three relaxation modes are coupled to each other due to the bilayer and the spherical structure of the vesicle. Most importantly, a higher fluid viscosity inside the vesicle shifts the crossover mode between the bending and the slipping to a larger value. As the vesicle parameters approach the unstable regions, the relaxation dynamics is dramatically slowed down, and the corresponding mode structure changes significantly. In some limiting cases, our general result reduces to the previously obtained relaxation rates.