Cartoon showing the basic structure of our model. The outflow (red region) lies between the wind and the envelope. Arrows (p_wind and p_envelope) denote the ram-pressure of the wind and the envelope. With wind we denote the cavity evacuated by the wind, with turbulent envelope we denote the turbulent envelope, and with outflow layer we denote the layer which contains the mixture of gas from the wind and gas from the envelope.