  The rheology of a three-dimensional granular jet during an impact is
investigated numerically. The cone-like scattering pattern and the sheet-like
pattern observed in an experiment [X. Cheng, et al. Phys. Rev. Lett. 99, 188001
(2007)] can be reproduced through our calculation. We discuss the constitutive
equation for granular jet impact in terms of our simulation. From the analysis
of an effective friction constant, which is the ratio between the shear stress
and the pressure the assumption of the zero yield stress would be natural in
our setup and the shear visocity is not small in contrast to the suggestion by
the experiment.
