  In this study we characterize the rheology of fluidized granular matter
subject to secondary forcing. Our approach consists of first fluidizing
granular matter in a drum half filled with grains via simple rotation, and then
superimposing oscillatory shear perpendicular to the downhill flow direction.
The response of the system is mostly linear, with a phase lag between the grain
motion and the oscillatory forcing. The rheology of the system can be well
characterize by the GDR-Midi model if the system is forced with slow
oscillations. The model breaks down when the forcing timescale becomes
comparable to characteristic time for energy dissipation in the flow.
