The microrheology of suspensions.

The spin and rotation of single rigid discs suspended in a liquid undergoing Couette flow and the translational and rotational motions of single suspended rigid spheres, rods and discs as well as the deformation of fluid drops in Poiseuille flow have been studied. With the exception of wall effects in Poiseuille flow quantitative agreement with theories due to Jeffery and Taylor were obtained. The existence of axial migration with fluid drops and its absence with rigid particles in Poiseuille flow was demonstrated and good agreement with an approximate theory found