A nacelle for an aircraft high-bypass jet engine, in which a jet engine having a longitudinal axis is mounted, the nacelle including a wall concentrically and at least partially surrounding the jet engine and defining with the latter an annular duct for fluid inner flow, including at the downstream end of the nacelle wall a passage section of a flow outlet. The nacelle includes a displacement mechanism displacing on request a portion of the nacelle wall to modify the passage section of the flow outlet through which a major portion of the flow escapes, the displacement forming in the nacelle wall at least one opening through which a small portion of a leak flow, naturally escapes. The nacelle further includes a fluid device that uses a fluid for compelling the leak flow to flow along the outer face of the portion of the nacelle wall located downstream relative to the at least one opening.