Intrinsic toroidal rotation in a tokamak can be driven by turbulent momentum
transport due to neoclassical flow effects breaking a symmetry of turbulence.
In this paper we categorize the contributions due to neoclassical effects to
the turbulent momentum transport, and evaluate each contribution using
gyrokinetic simulations. We find that the relative importance of each
contribution changes with collisionality. For low collisionality, the dominant
contributions come from neoclassical particle and parallel flows. For moderate
collisionality, there are non- negligible contributions due to neoclassical
poloidal electric field and poloidal gradients of density and temperature,
which are not important for low collisionality.