  Recent studies have highlighted that oscillatory and time-dependent shear
flows might help increase flowability of dense suspensions. While most focus
has been on cross-flows we here study a simple two-dimensional suspensions
where we apply simultaneously oscillatory and stationary shear along the same
direction. We first show that the viscosities in this set-up significantly
decrease with an increasing magnitude of the oscillations, contrary to previous
claims. The decrease can be attributed to the large decrease in the number of
contacts and an altered microstructure as the magnitude of the oscillation is
increased. As a sub-result we find both an extension to the $\mu(J)$-rheology,
a constitutive relationship between the shear stresses and the shear rate,
valid for pure oscillatory flows and with a higher shear-jammed packing
fraction for suspensions composed of frictional particles compared to
steady-shear conditions.
