Collisional Damping of Wakes in Perturbed Planetary Rings

The collisional damping of satellite wakes at the edge of the Encke gap of Saturn's rings is studied using N-body simulations. The self-gravity of the ring particles is neglected. The wake damping rate is determined as a function of ring optical depth, particle size, and the coefficient of restitution of colliding particles. The amplitude decay of the wakes is nonuniform and is not a simple function of the azimuthal distance from the satellite. Surprisingly, the wake decay rate is found to be a non-monotonic function of the ring optical depth. The evolution of the wakes is quite sensitive to changes in the assumed functional form of the coefficient of restitution. Secondary wakes that evolve over multiple synodic periods are observed at larger radial separations from the perturbing satellite. The radial migration of particle guiding centers that was noted in our previous paper is explained and more fully explored.