  Experiments on the impact of a densely-packed jet of non-cohesive grains onto
a fixed target show that the impact produces an ejecta sheet comprised of
particles in collimated motion. The ejecta sheet leaves the target at a
well-defined angle whose value agrees quantitatively with the sheet angle
produced by water jet impact. Motivated by these experiments, we examine the
idealized problem of dense granular jet impact onto a frictionless target in
two dimensions. Numerical results for the velocity and pressure fields within
the granular jet agree quantitatively with predictions from an exact solution
for 2D perfect-fluid impact. This correspondence demonstrates that the
continuum limit controlling the coherent collective motion in dense granular
impact is Euler flow.
