Logarithmic color maps of the density field in the orbital plane. The arrows stand for the velocity field; the black to white color map indicates their increasing magnitude. The orbital speed of Vela X-1, v_orb ∼ 284 km s⁻¹, is represented (linear scale). The black dashed line indicates the Mach-1 contour. The radial extension of the simulation domain relative to the orbital separation corresponds to the green dashed delimited regions in Fig. 1, which is approximately the Roche lobe of the accretor. Bottom panel: LF configuration. Top panel: HS configuration.