Mass-weighted argument of pericenter of the circumprimary disk versus time. The top panel shows results for a 2D (green circles) and a 3D model (orange circles). The 2D model predicts a retrograde precession of the circumprimary disk at a rate of about 6 binary periods for a full revolution. The precession rate resulting from the 3D model is still retrograde, but orders of magnitude slower. The long-term behavior of the 3D model is displayed in the bottom panel. The solid line represent an average over 10 T intervals. See text for further details.