Fig. 2. A similar behavior to that found for U tubes has been reported in partitioned
rectangular containers. Here is the sketch of a partitioned container similar to that
of Ohtsuki et al. (1998), who used a vertical wall to separate a container into two
regions, leaving the bottom connected. The experiment is started with the level of
grains in both regions at the same height. Vertical vibrations induce a migration of
grains, so after vibration, the level of grains in one region ends up higher than in the
other (the higher region can be either the wider or the narrower).
Akiyama et al.(2001)
studied a similar system with L1=L2