  Anisotropic flows ($v_1$, $v_2$, $v_3$ and $v_4$) of light fragments up till
the mass number 4 as a function of rapidity have been studied for 25
MeV/nucleon $^{40}$Ca + $^{40}$Ca at large impact parameters by Quantum
Molecular Dynamics model. A phenomenological scaling behavior of rapidity
dependent flow parameters $v_n$ (n = 1, 2, 3 and 4) has been found as a
function of mass number plus a constant term, which may arise from the
interplay of collective and random motions. In addition, $v_4/{v_2}^2$ keeps
almost independent of rapidity and remains a rough constant of 1/2 for all
light fragments.
