  The impacts of granular jets for both frictional and frictionless grains in
two dimensions are numerically investigated. A dense flow with a dead zone
emerges during the impact. From our two-dimensional simulation, we evaluate the
equations of state and the con- stitutive equations of the flow. The asymptotic
divergences of pressure and shear stress similar to the situation near the
jamming transition appear for the frictionless case, while their exponents are
smaller than those of the sheared granular systems, and are close to the
extrapolation from the kinetic theoretical regime. In a similar manner to the
jam- ming for frictional grains, the critical density decreases as the friction
constant of grains increases. For bi-disperse systems, the effective friction
constant defined as the ratio of shear stress to normal stress, monotonically
increases from near zero, as the strain rate increases. On the other hand, the
effective friction constant has two metastable branches for mono-disperse
systems because of the coexistence of a crystallized state and a liquid state.
