Time-Incremented Multiscale Evolution (TIME): A Code-Independent Method for Time-Domain 3D Hydrodynamics and its Application to Roche Lobe Overflow

Abstract: Context. Many critical physical processes, such as Roche lobe overflow, strain modern simulation methods due to their durations and multidimensionality. Aims. We employ a novel method of time-domain multidimensional simulations to provide the first grid-based time domain 3D model of Roche lobe overflow using VH-1. Methods. Using a piecewise approach which alternates between high-resolution 3D dynamic modeling and computationally fast evolutionary modeling, we present and test a method capable of self-scaling variable time resolution at greatly reduced computational cost. Results. We find mass transfer in the test high mass x-ray binary M33 X-7 to be unstable and fully conservative in both mass and angular momentum transport onto the accretion disk beyond f >~ 1.01. This phase begins on thermal timescales and accelerates to span < 100 yrs beyond f >= 1.1, while the non-conservative stable phase of f <~ 1.01 occurs on roughly nuclear timescales. Conclusions. We identify a critical point f ~ 1.01 which terminates stable overflow, which may correspond to the point Mdot_L1 ~ Mdot_wind or Mdot_L1 ~ 10^-6 M_solar/yr in the general case.