Abstract
A method for measuring the motion of hydrodynamically interacting rigid spherical particles of arbitrary three-dimensional configurations and the flow fields due to the motion of the particles, under the condition of vanishing particle Reynolds number, is presented. The particles and the fluid were chosen to have the same index of refraction so that particles would be optically transparent. Two fluorescent dyes and suitable filter sets were used for the visualization of particle motions and fluid flows, which separates tracer images from the others. The motion of an individual sphere was measured using 3-D PTV and the flow field in a plane was measured simultaneously using 2-D PIV. The method was applied to the problem of rising spheres in a quiescent fluid and the time evolution of particle configurations and the flow fields around the particles were illustrated.
