  Extended-MHD modeling of DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614
(2002)] quiescent H-mode (QH-mode) discharges with nonlinear NIMROD [C. R.
Sovinec et al., J. Comput. Phys. 195, 355 (2004)] simulations saturates into a
turbulent state but does not saturate when the steady-state flow inferred from
measurements is not included. This is consistent with the experimental
observations of the quiescent regime on DIII-D. The simulation with flow
develops into a saturated turbulent state where the n=1 and 2 toroidal modes
become dominant through an inverse cascade. Each mode in the range of n=1-5 is
dominant at a different time. Consistent with experimental observations during
QH-mode, the simulated state leads to large particle transport relative to the
thermal transport. Analysis shows that the amplitude and phase of the density
and temperature perturbations differ resulting in greater fluctuation-induced
convective particle transport relative to the convective thermal transport.
Comparison to magnetic-coil measurements shows that rotation frequencies differ
between the simulation and experiment, which indicates that more sophisticated
extended-MHD two-fluid modeling is required.
