Dispersion and Re-aggregation of Particles in a Suspension Flowing in an Abrupt Contraction Channel

抄録

A flow experiment of a dilute suspension and aggregation/dispersion analysis of fine particles in a non-uniform shear field were performed. We investigated the dispersion characteristics in a microchannel with an abrupt contraction section. The dispersed particles and dispersion media were polystyrene and aqueous glycerine, respectively. The particle diameter and solid volume fraction were 3.5 μm and 0.001, respectively. Citric acid (0.5 and 1.0 wt%) was added as a non-ionic salt in order to investigate the effect of the aggregational force. The suspension was introduced into the microchannel with a syringe pump at a volume rate of 0.3 μl・min^-1. The aggregation/dispersion characteristics of the fine particles were observed with a microscope and analyzed by image analysis. We observed the breakup and re-aggregational behavior of the fine particles in a dilute suspension. The cumulative frequencies of fine particles fluctuated through the channel. From the results, we posit the possibility that the non-uniformity of ions affect the aggregational characteristics of fine particles in a shear flow.