| Summary: | An experimental investigation of a sphere performing torsional oscillations in a Stokes flow is presented. A novel experimental set up was developed which enabled the motion of the sphere to be remotely controlled through application of a magnetic field. The response of the sphere to the applied field was characterised and good agreement with a theoretical model was found. The effect of nearby boundaries were investigated in two cases; when the rotational axis of the sphere was (1) parallel and (2) perpendicular to the normal to the bounding surface. The interaction between a torsionally oscillating sphere and an otherwise stationary sphere was then studied for various combinations of spheres. The effect that a tether connecting the spheres had on the dynamics of two interacting spheres was considered by comparing tethers of different materials. Finally, a multi-body configuration of spheres connected by elastic tethers which propelled itself in a Stokes flow when actuated magnetically was developed. Throughout the investigation Particle Image Velocimetry, a quantitative flow visualisation technique, was used to determine the resultant flows and provide insight into the fluid dynamics.
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