Angular momentum transport in simulations of accretion disks

In this paper, we briefly discuss the ways in which angular momentum transport is included in simulations of non-self-gravitating accretion disks, concentrating on disks in close binaries, Numerical approaches fall in two basic categories: particle-based Lagrangian schemes, and grid-based Eulerian techniques. Underlying the choice of numerical technique are assumptions that are made about disk physics, and in particular, about the angular momentum transport mechanism. Grid-based simulations have generally been of hot, relatively inviscid disks whereas particle-based simulations are more commonly of cool, viscous disks. Calculations of the latter type have been instrumental in developing a model for the superhump phenomenon. We describe how we use an artificial viscosity term to introduce angular momentum transport into our smoothed particle hydrodynamics (SPH) disk code.