Tidal disruption flares are thought to be evidences for quiescent supermassive black holes
at the centers of inactive galaxies, because of those characteristic time variations with large
luminosities. However, there is poorly known about tidal disruption and subsequent mass
fallback process for stars approaching supermassive black holes on bound orbits. We perform
three dimensional Smoothed Particle Hydrodynamics simulations of those processes with a
pseudo-Newtonian potential. We find that the mass fallback rate decays with the expected -5/3
power of time for parabolic orbits, albeit with a slight deviation due to the self-gravity of the stellar
debris. For eccentric orbits, however, there is a critical value of the orbital eccentricity, significantly
below which all of the stellar debris is bound to the supermassive black hole. All the mass therefore
falls back to the supermassive black hole in a much shorter time than in the standard, parabolic case.
The resultant mass fallback rate considerably exceeds the Eddington accretion rate and substantially
differs from the -5/3 power of time. We also show that general relativistic precession is crucial for
accretion disk formation via circularization of stellar debris from stars on moderately eccentric orbits.
We also discuss how a black hole spin affects the debris circularization by SPH simulations with
Post-Newtonian corrections.