Three related problems of interest to models of eccentric disks in close binary systems are investigated. For the 3:1 resonance model of superhump binaries, it is found that nonresonant stresses from the m = 2 tidal potential component phi2 weaken the tidal eccentric instability mechanism at the 3:1 resonance driven by phi3. The phi2 potential attempts to expel material from the 3:1 resonance, leading to a lower density there and hence lower resonant angular momentum flux. This process can be understood in terms of the effects of orbit crossing in limiting the radial extent of the disk. Disk precession is found to be due to a combination of the effects of pressure waves in the eccentric mode resonant wave stresses and direct axisymmetric tidal forces from the companion. Wave stresses give rise to a time-varying precession rate. The observed secular increase in the superhump period during superoutburst can be explained as due to a slight ongoing contraction of the disk by about 10-15 percent in radius.
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Stephen H. Lubow (1992) studied this question.