  We investigate the rheological properties of an assembly of inelastic (but
frictionless) particles close to the jamming density using numerical
simulation, in which uniform steady states with a constant shear rate
$\dot\gamma$ is realized. The system behaves as a power-law fluid and the
relevant exponents are estimated; e.g., the shear stress is proportional to
$\dot\gamma^{1/\delta_S}$, where $1/\delta_S=0.64(2)$. It is also found that
the relaxation time $\tau$ and the correlation length $\xi$ of the velocity
increase obeying power laws: $\tau\sim\dot\gamma^{-\beta}$ and
$\xi\sim\dot\gamma^{-\alpha}$, where $\beta=0.27(3)$ and $\alpha=0.23(3)$.
