The NSH equilibrium solutions of the dust and gas velocity. (a, b) The dust (blue) and gas (green) velocity in the radial direction and the azimuthal direction, respectively, as a function of τ_s. The velocity in the azimuthal direction is relative to the Keplerian velocity v_K. Different line styles correspond to different dust-to-gas ratios ϵ. (c, d) The gas velocity relative to the dust in the radial and azimuthal direction, respectively. (e) The resulting polarization angle χ from birdie-like alignment.