Equation of state in a model granular suspension

We experimentally investigate the stationary sedimentation of an assembly of buoyant cylinders in a rotating Hele-Shaw cell. The resulting tunable centripetal force allows exploring various states of the system. We find that local density fluctuations are in one-to-one correspondence with its mean, irrespective of the potential. From this relation, we derive a statistical pressure that appears to be proportional to a hydrodynamic pressure built from a mixture model over the whole range of explored packing fractions, allowing us to define an effective temperature in the medium. This quantity, which only depends on the density contrast between the grains and the liquid, entertains a simple relation to the dissipated energy.