  An analytical treatment for the sedimentation rate of disordered suspensions
is presented in the context of a resistance problem.
  From the calculation it is confirmed that the lubrication effect is important
in contrast to the suggestion by Brady and Durlofsky (Phys.Fluids Vol.31, 717
(1988)). The calculated sedimentation rate agrees well with the experimental
results in all range of the volume fraction.
