Inertial migration of spherical elastic phytoplankton in pipe flow

Abstract

Inertial migration of spherical elastic phytoplankton in a microscale pipe was investigated in Reynolds number range of 10-100. Three-dimensional position of migrating cells was obtained using digital in-line holographic microscopy. Characteristics of inertial migration were studied by analyzing the spatial distribution of cells. As Reynolds number increases, Segre-Silberberg annulus clearly appeared at the same measurement location. The effect of elastic shell compliance was experimentally investigated by comparing the probability density function of normal and hardened cells. As Re increases, the equilibrium positions of both normal and hardened cells drift toward the tube wall as the result of balanced lifts. The degree of inertial-migration development of elastic cells is slower than that of hardened cells. These results will be useful for better understanding of dynamic behaviors of phytoplankton, especially inertial migration in pipe flow.