Experimental results on mean inclination angle and its fluctuation due to thermal noise in tank-treading motion of a vesicle in shear flow as a function of vesicle excess area, normalized shear rate, viscosity, and viscosity contrast between inner and outer fluids, $ϵ$, are presented. Good quantitative agreement with theory made for $ϵ=1$ was found. At $ϵ>1$ the dependence is altered significantly. Dependence of the vesicle shape on shear rate is consistent with theory. A tank-treading velocity of the vesicle membrane is found to be a periodic function close to that predicted by theory.

• Received 8 June 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.258101