Morshed Adnan, Dutta Prashanta, Hossan Mohammad Robiul, Dillon Robert
School of Mechanical and Materials Engineering Washington State University, Pullman, WA 99164.
Department of Engineering and Physics University of Central Oklahoma, Edmond, OK 73034.
Phys Rev Fluids. 2018 Oct;3(10). doi: 10.1103/physrevfluids.3.103702. Epub 2018 Oct 24.
Deformation of flexible vesicles suspended in a fluid medium due to an applied electric field can provide valuable insight into deformation dynamics at a very small scale. In an electric field, the response of the vesicle membrane is strongly influenced by the conductivity of surrounding fluid, vesicle size and shape, and the magnitude of applied field. We studied the electrodeformation of vesicles immersed in a fluid media under a DC electric field. An immersed interface method is used to solve the electric field over the domain with conductive or non-conductive vesicles while an immersed boundary method is employed to solve fluid flow, fluid-solid interaction, membrane mechanics and vesicle deformation. Initial force analysis on the membrane surface reveals almost linear influence of vesicle size, but the vesicle size does not affect the long-term deformation which is consistent with experimental evidence. Highly nonlinear effect of the applied field as well as the conductivity ratios inside and outside of the vesicle are observed. Results also point towards an early linear deformation regime followed by an equilibrium stage for the membranes. Modeling results suggest that electrodeforming vesicles can create unique external flows for different conductivity ratios. Moreover, significant influence of the initial aspect ratio of the vesicle on the force distribution is observed across a range of conductivity ratios.
悬浮在流体介质中的柔性囊泡在施加电场作用下发生的变形，能够为极小尺度下的变形动力学提供有价值的见解。在电场中，囊泡膜的响应受到周围流体的电导率、囊泡大小和形状以及外加电场强度的强烈影响。我们研究了在直流电场作用下浸入流体介质中的囊泡的电致变形。采用浸入界面法求解包含导电或非导电囊泡的区域上的电场，同时采用浸入边界法求解流体流动、流固相互作用、膜力学和囊泡变形。对膜表面的初始力分析表明囊泡大小几乎呈线性影响，但囊泡大小并不影响长期变形，这与实验证据一致。观察到外加电场以及囊泡内外电导率比的高度非线性效应。结果还表明膜存在一个早期线性变形阶段，随后是平衡阶段。建模结果表明，电致变形的囊泡对于不同的电导率比能够产生独特的外部流动。此外，在一系列电导率比范围内，观察到囊泡的初始纵横比对力分布有显著影响。
