Particle Response to Low-Reynolds-Number Oscillation of a Fluid in Microgravity

This works presents an experimental study on the response of a particle to the movement of the fluid in which the particle is suspended. The stationary solution to Tchen's equation of motion was used to design experiments to determine the influence of the Basset history force. In the experiments, the stationary amplitude ratio and phase difference between the fluid and the particle motion are measured in a fluid cell containing a particle that is supported by a tether to counteract the effect of gravity. Particle and cell locations at the limits of motion are measured with great precision by applying electronic holography. The measured particle responses closely match the theoretical predictions for the full solution for a variety of fluid to particle density ratios, Reynolds numbers, and frequencies of oscillation. The experiments reinforce the importance of the Basset history term for moderate to high frequency flows. [PUBLICATION ABSTRACT]