Abstract
Sedimentation and electrophoresis of porous materials; colloidal floc and colloidal particles covered with adsorbing polyelectrolytes, are visited to examine the characteristic length scale of transport phenomena. In the sedimentation, the size of floc is dominative in the determination of Stokes drag, while the permeability is determined by the large pore in flocs. However, if the floc is placed in the electric field, outside fluid can easily penetrate into the floc by means of electric osmosis. In this regime, the characteristic length scale of hydrodynamic drag is Debye length. In the case of electrophoresis of latex particle covered with adsorbing polyelectrolyte, the characteristic length scale of permeability was estimated same as the distance between charged segments.
