Examples of deviations from uniform angular distribution defined by Eq. (16). The red curves are their representation in polar coordinates (P(ψ), ψ) as indicated in the lower left panel. The panels from left to right correspond to n = 1, 2, 3, 4. The upper (lower) panels correspond to the negative (positive) sign of v_n = ∓1∕6. The black dot-dashed circles correspond to uniform distribution P(ψ) = 1.