Radial velocity for selected wind models 300-1. The black line denotes the model without either X-ray irradiation or clumping, while blue and red lines denote models with the same X-ray irradiation (with the same L_X and D) and different clumping: without clumping (blue solid) and with C_c = 10 (red dashed). Here the clumping is allowed to affect the ionization structure only directly and not via the mean density (mass-loss rate). Overplotted is the value of the ionization parameter Eq. (12) at the location of the velocity kink. Left panel: model with L_X = 10³⁶ erg s⁻¹ and D = 200 R_⊙. Right panel: model with L_X = 10³⁸ erg s⁻¹ and D = 700 R_⊙.