Instantaneous flow in a meridional slice at φ = π, centered on a spiral wake at R/r_in ≈ 7.5 and time 500t_in in run M3B10. The gas density is represented by filled contours spanning four orders of magnitude. The orientation of the meridional gas velocity is represented with colored arrows, blue (resp. green) being oriented away (resp. toward) the disk midplane. At the wake location, the midplane pressure scale height h_mid/r_in ≈ 0.3.