Abstract
The motion of a sphere sedimenting through a viscoelastic worm-like micelle solution (cetyltrimethylammonium bromide and sodium salicylate in deionized water) in a square duct is experimentally investigated using a PIV (Particle Image Velocimetry). Abrupt changes in sedimenting velocity of a sphere are attributed to the onsets of strong downward flow behind a sphere which generates shear waves in the fluid. Subsequent oscillations in sphere velocity have the same frequency of the standing waves propagating along the square duct which forms a waveguide.
