Deformation of a capsule in a low Re number simple shear flow

Deformation of a small capsule in a flow field is an important phenomenon in many research fields such as a blood flow in a small artery. In this research, the deformation of a capsule is experimentally investigated under a low Re number simple shear flow condition. We used two kinds of capsules and changed their membrane visco-elasticity and the inner and outer viscosity. We also made a capsule with spheroid shape. The effects of the membrane visco-elasticity, the ratio of inner to outer viscosity and the initial aspect ratio on the deformation and the inclination of the capsule are discussed. The results show that the deformation of a spherical capsule can be described mainly by the Ca number. The inclination of a capsule increases with increasing the membrane viscosity and with decreasing the ratio of inner to outer viscosity. In the case of spheroid capsule, the deformation and the inclination oscillate with time. The oscillation is strongle affected by the initial aspect ratio, however, the time-mean values are not so affected. These results are compared with the former researches, and show good agreement.