1. Introduction

Final goal:
to understand "DISPERSED MEDIA" (suspensions, granular materials, etc)
   to obtain the (good!) MODEL

Unclear problems:
non-Newtonian properties
normal stress differences
history dependence
pattern formations (particle migrations)
even in Stokes approximation (time reversal!)

Two approaches:
Macroscopic (two-fluid models)
conservation laws & physical insights          make the MODEL
Microscopic
particle-particle interaction (building block)        derive the MODEL
Prosperetti and co-workers [Int. J. Multiphase Flow (2001) Vol.27 p.237, etc],
and my current work here