  We consider the development of anisotropic flow in an expanding system of
particles undergoing very few rescatterings, using a kinetic-theoretical
description with a nonlinear collision term. We derive the scaling behaviors of
the harmonic coefficients $v_n$ with the initial-state eccentricities and the
mean number of rescatterings, and argue that hexagonal flow $v_6$ should follow
a nontrivial behavior, different from that of the lower harmonics. Our findings
should be observable in experimental data for small systems.
