Dynamics of Fluid Vesicles in Oscillatory Shear Flow

作者：Noguchi Hiroshi^*

来源：Journal of the Physical Society of Japan, 2010, 79(2): 024801.

DOI：10.1143/JPSJ.79.024801

• vesicle
• oscillatory flow
• synchronization
• limit cycle

The dynamics of fluid vesicles in oscillatory shear flow was studied using differential equations of two variables: the Taylor deformation parameter and inclination angle theta. In a steady shear flow with a low viscosity theta(0) of internal fluid, the vesicles exhibit steady lank-treading motion with a constant inclination angle theta(0). In the oscillatory flow with a low shear frequency, theta oscillates between +theta(0) or around theta(0) for zero or finite mean shear rate (gamma) over dot(m) respectively. As shear frequency f(gamma) increases. the vesicle oscillation becomes delayed with respect to the shear oscillation, and the oscillation amplitude decreases. At high f(gamma) with (gamma) over dot(m) = 0, another limit-cycle oscillation between theta(0) - pi and -theta(0) is found to appear. In the steady flow, theta periodically rotates (tumbling) at high eta(in), and theta and the vesicle shape oscillate (swinging) at middle eta(in) and high shear rate. In the oscillatory flow, the coexistence of two or more limit-cycle oscillations can occur for low f(gamma) in these phases. For the vesicle with a fixed shape, the angle theta rotates back to the original position after all oscillation period. However, it is found that a preferred angle can be induced by small thermal fluctuations.

• 出版日期2010-2